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HomeMy WebLinkAboutX2021-1680 - Alternative Material & MethodsXZo2i- ►�� CITY OF NEWPORT BEACH COMMUNITY DEVELOPMENT DEPARTMENT BUILDING DIVISION 100 Civic Center Drive I P.O. Box 1768 I Newport Beach, CA 92658-8915 www.newportbeachca.gov I (949) 644-3200 CASE NO.: 2022-100 ❑ REQUEST FOR MODIFICATION TO PROVISIONS OF TITLE 9 (FIRE CODE) OR TITLE 15 (BUILDING CODE) OF THE NEWPORT BEACH MUNICIPAL CODE (See Reverse for Basis for Approval) (Fee $291) ZREQUEST FOR ALTERNATE MATERIAL OR METHOD OF CONSTRUCTION (See Reverse for Basis for Approval) (Fee $291) For above requests, complete Sections 1, 2 & 3 below by printing in ink or typing. JOB ADDRESS: III FOR STAFF USE ONLY III Plan Check # 21\1- ZO 2O # of Stories 5 Occupancy Classification3 Use of Building YU�9 -:�A-2Tt-lE�1TS # of Units _O Project Status P�AoN C_+FEO-V—' Construction Type ::A�Lt -- S Verified by h\p_ No. of Items ) Fee due 9�( DISTRIBUTION: Owner Plan Check -OK - Petitioner ❑ Inspector ❑ Fire ❑ Other PETITIONER: SITE ADDRESS: 1660 Dove Street Petitioner AO (Kara Sutch) Owner _ Arya bhata Group LLC (Petitioner to be architect or engineer) Address 520 Newport Center Drive, Suite 480 Address 144 N. Orange Street Newport Beach Zip92660 Orange Zip 92866 Daytime Phone 440-666-5779 Daytime Phone ( ) 714-639-9860 ( ) Email:_ karas@aoarchitects.com 2 1 REQUEST: Submit plans if necessary to illustrate request. Additional sheets or data may be attached. To modify the prescriptive 1 hour rated floor assembly included in CBC Ta ble 721.1(3) Item 13-1.4 by replacing the double wood floor with a layer of 2-inch thick hard rock concrete over 19/32-in wood structural panel. (JUSTIFICATION/FINDINGS OF EQUIVALENCY: - California Building Code, Section 722, allows forth eestablishment of the fire resistance of _ combinations of materials by calculation in lieu of a listed assembly, Forth proposed assembly, the ceiling and floor construction is similar to the prescriptive assembly included in Table 721.1(3) of the CBC. Non-combustible concrete floor topping will provide better performance _ under fire and high temperature conditions tot he prescriptive double wood floor. The specifics of the non-combustible topping resistance are outlined in the attached, "Engineering Judgment 1-Hour Floor Ceiling Assemblies (California Building Code);' by Rolf Jensen and - Associates, Inc., dated July 16, 2013. Position Principal Petitioner's Kara Sutch Signature CA Professional Lic. # Steven Gaffney 19676 CODE SECTIONS: Table 721.1(3) Item 13-1.4 02-06-23 FOR STAFF USE ONLY DEPARTMENT ACTION: In accordance with: /..CBC 104.11/CFC 104.9 (Alternate materials & methods) ❑ Concurrence from Fire Code Official is required. ❑ Approved ❑ Disapproved _ By: Date M�Request (DOES DOES NO� lessen any fire protection requirements. Request (DO ) (DOES_N� lessen the structural integrity ❑ CBC 104.10/CFC 104.8 (CBC Modification) ❑ Written Comments Attached The Request is: K— Granted ❑ Denied (See reverse for appeal information) ❑ Granted (Ratification required) Conditions of Approval: __ _....� CHIEF SU!I. C�1N O; C FI ' IA.l_ Signature — Position Print Name i .--,-t.l F�r �} Date �n - Jto APPEAL OF DIVISION ACTION TO THE BUILDING BOARD OF APPEALS (See Reverse) (Signature, statement of owner or applicant, statement of reasons for appeal and filing fees are required.) 1 CASHIER RECEIPT NUMBER: I NV pco07+J33 Forms\modif 07/01/21 AO Architecture. Design. 144 N. Orange Street, Orange, CA 92866 T714.639.9860 aoarchitects.com Relationships. February 6, 2023 City of Newport Beach Community Development Department 100 Civic Center Drive Newport Beach, CA 92660 Melissa Kubischta, SE Civil Engineer- Plan Check Re: Plan Check Number 2117-2020 Newport Crossing Apartments 1660 Dove Street Newport Beach, CA 92658 Melissa, As permitted in CBC 104.11, the purpose of this letter is to request the use of an alternative material, design and method of construction for the two-story corridor openings on the project. Subject: Per Table 721.1(3) Item 13-1.4, a double wood floor is called for in order to provide a 1-hour floor assembly in the corridor as required by other sections of the code. Discussion: A thickness of 2" minimum concrete hard rock topping is proposed in place of one layer of the wood flooring.. • Section 703.3 Item 4 allows engineering analysis is a method for determining fire resistance. o See attached engineering judgments for the 2" hard rock topping assembly. • Section 703.3 Item 5 also allows for Alternate materials, design and methods of construction as requested herein. • Section 722.6.2.4, states that an upper membrane needs to have a contribution to fire resistance of not less than 15 minutes in Table 722.6.2(1). o The assembly is the same as that listed in 721.1(3) Item 13-1.4 and the sub floor is 19/32 structural panel, which exceeds the value of 15/32 structural panel listed with a rating of 15 minutes in Table 722.6.2(1). o The 2" hard rock is in addition to the 15-minute membrane. Note that 1-1/2" thickness of concrete provides at least 18-minutes of time per the Fire Protection Planning Report Number 13, page 4. • The attached Engineering Judgement letter discusses the proposed material for the floor assembly. The letterwas based upon the 2010 California Building Code. The project is subject to compliance with the 2019 California Building Code. o 0n various pages Table 720.1(3)Items 13-1.2 and 13-1.4 are referenced. There is no change between the 2010 and 2019 Table other than the Table number is now 721.1(3). o On page 3 CBC Section 720 is referenced. The applicable section in the 2019 CBC is Section 721. o On page 4 Table 721.6.2(1) is referenced. There is no change between the 2010 and 2019 Table other than the Table number is now 722.6.2(1). • See detail 8/ADi.1.3 for a typical bottom of wall detail. The sealant for the gypsum board at the wall provides continuity for the fire rating between the floor to wall intersection. This is consistent with the genera[ information in the GA Manual for sound isolation construction. Conclusion: In our opinion, the use of hard rock in lieu of a finish layer of flooring provides a 1-hour assembly. Thank you for your consideration. Please feel free to contact AO with any further questions. Kara Sutch I Principal karas(aaoarchitects corn Page 1 of 1 79 i?JA ROLF JENSEN & ASSOCIATES, INC. GLOBAL FIRE PROTECTION CONSULTANTS ENGINEERING JUDGMENT 1-HOUR FLOOR/CEILING ASSEMBLIES (CALIFORNIA BUILDING CODE) 79 RJA ROLF JENSEN & ASSOCIATES, INC. GLOBAL FIRE PROTECTION CONSULTANTS 2950 Buskirk Avenue Suite 225 Walnut Creek,CA 94597 USA worm.rjainc.con, +1 925-93B-3550 Fax: +1 925-938-3818 ENGINEERING JUDGMENT 1-HOUR FLOOR/CEILING ASSEMBLIES (CALIFORNIA BUILDING CODE) Prepared For: Architects Orange 144 North Orange Street Orange, CA 92866 Prepared by: Rolf Jensen & Associates, Inc. 2950 Buskirk Ave., Suite 225 Walnut Creek, CA 94597 July 16, 2013 RJA Project No. S60329 © 2013 Rolf Jensen & Associates, Inc. All Rights Reserved N EN SEEN N ME ENN EE ENE ENGINEERING JUDGMENT S60329 — Pagel 1-HOUR FLOOR/CEILING ASSEMBLIES July 16, 2013 (CALIFORNIA BUILDING CODE) TABLE OF CONTENTS INTRODUCTION...............................................................................I.............................1 FLOOR/CEILING ASSEMBLIES DESCRIPTION............................................................1 COMPARISON BETWEEN CBC ASSEMBLIES AND PROPOSED DESIGN.................2 DISCUSSION..................................................................................................................3 CEILING.......................................................................................................................3 FLOORJOIST..............................................................................................................3 FLOOR.........................................................................................................................4 DROPCEILING...........................................................................................................4 ASSEMBLYPRODUCTS.............................................................................................4 CONCLUSION.................................................................................................................5 APPENDIX A — ARCHITECTURAL DETAILS ENGINEERING JUDGMENT 1-HOUR FLOOR/CEILING ASSEMBLIES (CALIFORNIA BUILDING CODE) S60329 — Page 1 July 16, 2013 Rolf Jensen & Associates, Inc. (RJA) has been retained by Architects Orange to review the details of two proposed floor/ceiling assemblies to be used in the construction documents provided by Architects Orange. The proposed assemblies will be used for residential unit and egress balconies. RJA's review is based on the requirements of the 2010 California Building Code (CBC), as outlined in Chapter 7. The basis for this Engineering Judgment is two floor/ceiling assemblies outlined in CBC Table 720.1 (3), Minimum Protection for Floor and Roof Systems. Items 13-1.2 and 13-1.4 of this table provide the construction instructions for a double wood floor over wood joists, spaced 16 inches on center. It is the architect's desire to replace and modify some of the assemblies' components in order to meet their design goals while maintaining the 1-hour fire resistance rating of the systems. It is impractical for every variation of an assembly to be tested; therefore, Engineering Judgments are necessary to establish that the variation is consistent with other tested assemblies and fire protection concepts. Two details signed "Reviewed" with signature and date matching this document are also made a part of this document. FLOOR/CEILING ASSEMBLIES DESCRIPTION Table 720.1(3), Items 13-1.2 and 13-1.4 provide the construction components for the two 1-hour floor/ceiling assemblies that are based on a double wood floor supported by floor joists spaced 16 inches on center. The underside of the floor (ceiling) is comprised of 5/8- inch of cement/gypsum plaster on metal lath (Item 13-1.2), or 1/2-inch of Type X gypsum wallboard (Item 13-1.4). The proposed assemblies will replace the double wood floor with 2-inch minimum of hard rock concrete over 19/32-inch minimum wood structural panel with exterior glue sub -floor sheathing. The 13-1.2 ceiling will replace the 5/8-inch of cement/gypsum plaster with traditional 3-coat exterior cement plaster over metal lath, and the 13-1.4 ceiling will replace the 1/2-inch of Type X gypsum wallboard with 5/8-inch of Type X gypsum wallboard. An undefined waterproof membrane may be beneath the concrete finish. CBC Table 702.1(3) provides prescriptive listings of various assemblies and establishes hourly ratings for these assemblies. Generic products are used for prescriptive assemblies within Table 702.1(3). Generic products are also contemplated for each proposed design. ENGINEERING JUDGMENT 1-HOUR FLOOR/CEILING ASSEMBLIES (CALIFORNIA BUILDING CODE) S60329 — Page 2 July 16, 2013 COMPARISON BETWEEN CBC ASSEMBLIES AND PROPOSED DESIGN The following is a comparison between the CBC Table 720.1(3), Item 13-1.4 and the proposed design: Ceiling (Gypsum or Plaster) Floor Joist Floor (Table 720.1(3) "Notes" from Item "m") Plaster (Item 13-1.2) Gypsum Wallboard (Item 13.1.4) Sub -Floor (sheathing) Finish Floor (topping) Cement or gypsum plaster on metal lath. Metal lath fastened with 1 1/2" by No. 11 gage by 7116" head barbed shanked roofing nails spaced 5" on center. Plaster mixed 1:2 for scratch coat and 1:3 for brown coat, by weight, cement to sand aggregate. 5/8" minimum thickness. 1/2" Type X Gypsum wallboard nailed to joists with 5d cooler or wallboard nails at 6" on center. End joints of wallboards centered on joists. Wood joists 16' on center 15/32-inch wood structural panels with exterior glue. 19/32-inch wood structural panel or a layer of Type I Grade M-1 particleboard no less than 5/8-Inch thick. Same Same Same — Traditional 3-coat exterior cement plaster. 5/8" Type X Gypsum wallboard nailed to joist with 6d cooler or wallboard nails at 6" on center. End of joints of wallboards centered on joists. Same. 19/32" minimum wood structural panels with exterior glue. 2" minimum hard rock concrete (over an undefined waterproof membrane). ENGINEERING JUDGMENT S60329 — Page 3 1-HOUR FLOOR/CEILING ASSEMBLIES July 16, 2013 (CALIFORNIA BUILDING CODE) DISCUSSION Ceiling A. Cement Plaster. A traditional 3-coat system of cement plaster is to be used similarly to the prescriptive assemblies. B. Gypsum Wallboard. Gypsum boards used in the Proposed Design are similar to those of the tabled Prescriptive Assemblies. The use of gypsum boards with a greater thickness will provide a better fire resistance rating. The proposed assembly increases the thickness from 1/2-inch to 5/8-inch Type X. The Gypsum Association Manual includes two, 1-hour floor/ceiling assemblies utilizing a concrete floor topping and solid wood joist. Both assemblies use 1-5/8-inch thick perlite-sand concrete (lightweight concrete) and a proprietary 5/8-inch thick Type X gypsum board ceiling membrane. By comparison, the 5/8-inch thick Type X gypsum board in the proposed assembly is a 20% increased thickness to the 1/2-inch thick Type X gypsum board required by Table 720.1(3), Item 13-1.4, and is equivalent to the gypsum board thickness of the Gypsum Association Manual assemblies. If gypsum boards with a greater thickness are used, the fastener (nail or screw) shall be increased in length by the additional thickness of the membrane. 5/8-inch Type X gypsum wallboard is specified and must be provided as one of the board layers if multiple layers are used. Specified fasteners in the CBC assemblies are nails. Screws meeting ASTM C1002 shall be permitted to be substituted for the prescribed nails, one for one, when the length and head diameter of the screws equal or exceed those of the nails. The specified fastener spacing shall remain the same and fasteners shall be attached directly to joists. 2. Floor Joist CBC Section 720, Prescriptive Fire Resistance, does not establish floor joist sizes. Fire tests of floor assemblies include dead loads applied to the tested assembly based upon permitted code loads for the structural system. In essence, the tested assembly meets the structural requirements of the CBC. Any structural system designed by a licensed structural engineer is acceptable. ENGINEERING JUDGMENT 1-HOUR FLOOR/CEILING ASSEMBLIES (CALIFORNIA BUILDING CODE) 3. Floor S60329 — Page 4 July 16, 2013 All floor joists are assumed to be solid wood with minimum 2-inch nominal thickness. Joist spacing (16 inches on center) is specified by each item in Table 720.1(3). A. Sub -Floor (Sheathing). Sheathing used in the Proposed Designs includes thicker plywood sub -floor sheathing than those listed in the tabled Prescriptive Assemblies. Based on CBC Table 721.6.2(1), wood structural panels with larger thickness provide better fire resistance rating (15/32-inch: 10 minutes; 19/32-inch: 15 minutes). The use of thicker wood panels will provide improved fire resistance rating for the entire assembly. CBC Table 721.6.2(1) assigns 15 minutes to 19/32-inch floor sheathing. B. Finish Floor (Topping). The proposed assemblies include 2-inch thickness of regular weight concrete in lieu of a wood finish floor. Although concrete is a noncombustible material, its thermal insulation properties are less than wood (k - Thermal Conductivity measured in W/(m*K): Wood 0.13, Concrete 0.5), but with more than twice the thickness, the concrete will behave similarly to the wood. The concrete however will reduce air movement through the assembly. The slightly higher thermal conduction of concrete will allow a reduction of the temperature inside the floor/ceiling assembly. The thicker concrete layer will provide better insulation with similar characteristics to wood flooring. 4. Drop Ceiling The two proposed floor/ceiling assemblies will provide the required 1-hour rating. An additional drop ceiling may be provided. The drop ceiling and space above shall meet any other code requirements specific to the drop ceiling construction. 5. Assembly Products All products to be used in the two proposed assemblies are generic and will meet the construction listing for their use. Any product regulated by the CBC (such as screws referring to an ASTM Standard) will meet CBC requirements. ENGINEERING JUDGMENT S60329 — Page 5 1-HOUR FLOOR/CEILING ASSEMBLIES July 16, 2013 (CALIFORNIA BUILDING CODE) CONCLUSION The intent of CBC Table 720 is to allow the use of a prescriptive fire resistance approach with the use of generic products. The use of the same products having greater thickness provides better fire resistance rating as outlined by CBC Section 721, Calculated Fire Resistance. Noncombustible concrete floor topping will provide better performance under fire and high temperature conditions. Structural stability of the assembly will be approved by the project structural engineer. Ceiling construction will be similar to the Prescriptive Assemblies, and will provide the required fire resistance protection for the wood framing. Based upon the information provided by the design team and the above code analysis, it is our opinion that installation of the Proposed Design floor/ceiling assemblies, constructed at either interior or exterior locations, will provide an equivalent 1-hour fire resistance rating to the CBC Table 720.1(3), Items 13-1.2 and 13-1.4 assemblies. Prepared by: ROLF JENSEN & ASSOCIATES, INC. Thomas M. Dusza, P.E. OF EB/TMD/JSF:ga/ts 560329\RPTS7783CBC 1104 Date APPENDIX A ARCHITECTURAL DETAIL zi� I a, lj z g n Nfl A V-4" O.C. MAXIMUM NOTES: 1. STAPLES WITH EQUIVALENT HOLDING POWER AND PENETRATION SHALL BE PERMITTED TO BE USED AS ALTERNATE FASTENERS TO NAILS FOR ATTACHMENT TO WOOD FRAMING. 2, THE CEILING SHALL BE PERMITTED TO BE OMITTED OVER UNUSABLE SPACE, AND FLOORING SHALL BE PERMITTED TO BE OMITTED WHERE UNUSABLE SPACE OCCURS ABOVE. 3. SEE STRUCTURAL DRAWINGS FOR ADDITIONAL REQUIREMENTS, INCLUDING BUT NOT LIMITED TO, ATTACHMENT OF SUBFLOOR TO FLOOR FRAMING. 2" HARD•ROCK CONCRETE TOPPING SUBSTITUTED FOR FINISH FLOORING LAYER OF THE DOUBLE WOOD FLOOR OVER WATERPROOF MEMBRANE %32' WOOD STRUCTURAL PANELS WITH EXTERIOR GLUE SUBSTITUTED FOR THE 1613T WOOD STRUCTURAL PANELS WITH EXTERIOR GLUE SUBFLOOR LAYER OF THE DOUBLET WOOD FLOOR 3 COAT EXTERIOR CEMENT PLASTER ON EXPANDED METAL LATH. LATH FASTENED BY NO.11 GAGE BY 7116' BARBED SHANK ROOFING NAILS SPACED b' O.C. PLASTER MIXED 1:2 FOR SCRATCH COAT AND 1:3 FOR BROWN COAT, BY WEIGHT, CEMENT TO SAND AGGREGATE, I Table 7-C, Item 13 - 1.2 Modified 14 1 V-4" O.C. IfiildiONdi NOTES: 1. STAPLES WITH EQUIVALENT HOLDING POWER AND PENETRATION SHALL BE PERMITTED TO BE USED AS ALTERNATE FASTENERS TO NAILS FOR ATTACHMENT TO WOOD FRAMING. 2. THE CEILING SHALL BE PERMITTED TO BE OMITTED OVER UNUSABLE SPACE, AND FLOORING SHALL BE PERMITTED TO BE OMITTED WHERE UNUSABLE SPACE OCCURS ABOVE. 3. SEE STRUCTURAL DRAWINGS FOR ADDITIONAL REQUIREMENTS, INCLUDING BUT NOT LIMITED TO, ATTACHMENT OF SUBFLOOR TO FLOOR FRAMING. 22 HARD -ROCK CONCRETE TOPPING SUBSTITUTED. FOR FINISH FLOORING LAYER OF THE DOUBLE WOOD FLOOR OVER WATERPROOF MEMBRANE 1913T WOOD STRUCTURAL PANELS WITH EXTERIOR GLUE SUBSTITUTED FOR THE 16132, WOOD STRUCTURAL PANELS WITH EXTERIOR GLUE SUBFLOOR LAYER OF THE DOUBLE WOODFLOOR 518P TYPE X GYPSUM WALLBOARD (SUBSTITUTED FOR 1/2' TYPE X GYPSUM WALLBOARD). NAILED TO JOIST WITH 8d' COOLER OR WALLBOARD NAILS (SUBSTITUTED FOR 5d NAILS) AT' O.C. END JOINTS OF WALLBOARD SHALL BE CENTERED ON JOIST. FOR PROPERTIES OF COOLER OR WALLBOARD NAILS, SEE ASTM C 614, ASTM C 547 OR ASTM F 1667. I Table 7-C, Item 13 - 1.4 Modified 14 1 BUILDING CONSTRUCTION INFORMATION FROM THE CONCRETE AND MASONRY INDUSTRIES Analytical Methods of Determining Fire Endurance of Concrete and Masonry Members —Model Code Approved Procedures Fire endurance: A measure of the elapsed time during which a material or assembly continues to exhibit fire resistance under specified conditions of test and performance. As applied to elements of build- ings, fire endurrance shall be measured by the methods and to the criteria defined byASTM Methods E119, "Standard Methods of Fire Tests of Building Construction and Materials." (Fire endurance is a technical term.) Fire Resistance: The property of a material or assembly to withstand fire or give protection from it. As applied to elements of buildings, fire resistance is characterized by the ability to confine a fire or to continue to perform a given structural function, or both. (Fire resistance is a descriptive term.) Fire rating: A time required, usually expressed in hours, for an element in a building to maintain its particular fire-resistant properties. Model codes estab- lish the required fire ratings for various building ele- ments. (Fire rating or fire -resistance rating Is a legal term.) PART INTRODUCTION AND STANDARD FIRE TEST Fire -endurance periods for building components are normally determined by physical tests conducted accord- ing to ASTM El 19, "Standard Methods of Fire Tests of Building Construction and Materials." Provisions of the ASTM E 119 test require that specimens be subjected to a fire which follows the standard time -temperature curve shown in Fig, 1. Under the E119 standard, the fire endurance of a member or assem bly is determined by the time required to reach the fi rst of any of the following three end points: 1. Ignition of cotton waste due to passage of flame through cracks or fissures. NO. 13 OF A SERIES 2. A temperature rise of 3250F (single point) or 250OF (average) on the unexposed surface of the member or assembly. This is known as the heat transmission end point. 3. Inability to carry the applied design load, that is, structural collapse. Additional rating criteria for the fire endurance of a member or assembly include 1. Concrete structural members: in some cases the average temperature of the tension steel at any section must not exceed 800OF for cold -drawn prestressing steel or 11000F for reinforcing bars. Tests show that the respective steels retain approxi- mately 50% of their original yield strength at these temperatures. 2. For wall sections: the ability to resist the impact, erosion, and cooling effects of a specific size hose stream. 2500 W 2000 u oL 0 Fire lest lime, M Fig. 1. ASTM Standard E 119 time -temperature curve. Table 1 presents a listing of ASTM E119 end -point criteria and test conditions and outlines applicable end points of various concrete and masonry members and assemblies. ASTM E119 classifies beams, floors, and roofs as either restrained or unrestrained. A restrained member is one in which the thermal expansion is restricted. Reinforced concrete assemblies are generally classi- fied as restrained if they have continuity at interior sup- ports or are restricted from lateral movement at exterior supports. Table 2 should be referenced when determin- ing the presence of thermal restraint. The three model codes in the United States are the BOCA Basic National Building Code (B/NBC), ICBO Uniform Building Code (UBC), and SBCCI Standard Building Code (SBC). All require firetesting in accord- ance with ASTM E119 or analytical calculation based on ASTM E119 test data to satisfy all fire -resistance ratings required by the codes. These recently approved analytical methods present significant cost savings when compared to actual ASTM E 119 firetesting. ANALYTICAL METHODS Over many years the results of ASTM El l9standard fire tests have been analyzed. Along with standard fire tests there has been research and development of data on strength of steel and concrete at elevated temperatures, temperature distribution within concrete, verification and modification of theory, and the effects of restraining thermal expansion during heating. This testing and research forms the basis for analytical, or calculation, methods of determining fire endurance. Calculation of fire endurance can be classified into two categories: rational design and empirical design. Rational Design Rational design utilizes ASTM Ell9 fire -test results, data on steel and concrete strength at elevated temper- atures, temperature distribution within heated concrete, and the effects of support conditions and restraint of thermal expansion to perform structural engineering calculations. With the information listed, the engineer can then estimate by calculation the strength of members exposed to standard fire tests for various lengths of exposure time. Many fire tests have been performed to further develop and verify that rational design calculations cor- rectly estimate strengths of members exposed to the standard fire test. In a rational design calculation the fire endurance would be the length of time required forthe load capacity of the memberto be reduced to equal that of the applied loading. Empirical Design Empirical design utilizes tabulated results of ASTM Ell 9 fire tests and design aids, such as data on strength of heated concrete and steel, and temperature distribu- tions in concrete and masonryto calculate factors such as critical concrete thicknesses and cover. Application of empirical design is simpler than rational design in that no structural engineering calculations are required. END -POINT CRITERIA AND ANALYTICAL METHODS To analytically calculate the fire endurance of a given member it is useful to understand which end -point cri- teria will govern design of that member. As previously discussed, the first end point reached during the E119 fire test establishes the fire endurance period of the member. To further aid in understanding applica- bility of various end -point criteria, Table 1 should be referenced. Walls Concrete and masonry walls nearly always fail the heat transmission end point before allowing passage of flame or failing structurally. By examining heat transmission through various thicknesses of concrete, made with var- ious types of aggregates, from E 119 fire tests it is possi- ble to determine a given thickness or equivalent thick- ness of concrete, masonry, or brick to limit the temper- ature rise to below 250OF (average) or to 325OF (single point) as specified in ASTM E119. Beams Prestressed and normally reinforced concrete beams cannot be so easily categorized. The ability of a beam to carry a design load is the primary end point and is dependent on several factors which are accounted for in rational design methods. The rational design of a beam would consider the applied load, amount of concrete cover, beam spacing, span length and beam dimension, concrete and steel strengths, aggregate type in the con- crete, type of support, and restraint of thermal expan- sion. Considering the above factors, the structural designer would calculate the load -carrying capacity of the beam at a specific length of exposure time, that being the code -required -fire endurance period for the member being examined. Empirical design of beams in accordance with, for example, Appendix P of the SBC replaces rational design and considers the above factors for specifying concrete cover requirements for beams of different aggregate type concrete of varying width in both re- strained and unrestrained conditions as shown in Table 7. Tests show that with all other factors equal the primary factors in beam fire endurance are the amount of con- crete cover over prestressing strands or reinforcing steel bars and the method of support. Floors and Roofs Calculation of fire endurance of reinforced and pre- stressed concrete roof and floor slabs is based on both analysis of heat transmission and of load -carrying capacity at elevated temperatures. The heat transmis- sion end point can be analyzed similarly to walls. As with Table 1. Applicable End -Point Criteria and Test Conditions for Concrete and Masonry Members and Assemblies (Based on ASTM E119 Standard Fire Tests) Flame impinge - End 250OF average ment through point temperature cracks or rise or 325OF fissures point temp. sufficient Steel Restrained Hose Member rise on unex- to ignite Carryapplied temperature during stream posed surface cotton waste load end point testing test Bearing Yes Yes Yes Not considered No' Yes' Walls Nonbearing Yes Yes No load lied Not considered Yes' Yes' Floors Restrained Yes Yes Yes No' Yes No roofs Unrestrained Yes Yes Yes No No No Restraint not Columns No No Yes No imposed; test specifies simulation No of end connection Individual beams — restrained: prestressed or No No Yes Yes- Yes No reinforced Individual beams — unrestrained: No No Yes No No No prestressed or reinforced 'Non -load -beating walls are restrained but not loaded during tests. Bearing walla are loaded but not restrained. 'Hose stream tests apply only to those walls required to have a one -hour rating or greater. 'Restrained floor and roof slabs utilizing concrete beams spaced greater than 4' center -to -center must not exceed steel temperature limits of 1100-F (reinforcing steel) and 800-F (prestressing steel) for one-half the rating period or 1 hour, whichever is greater. 'Reinforcing steel in concrete beams or joists spaced greater than 4' center -to -center and cast monolithically with floors and columns must be maintained below 800'F (prestressing) and 1100-F (reinforcing) for 1 hour or one-half the desired rating period. whichever is greater. Table 2. Construction Classification, Restrained and Unrestrained I. Wall bearing A. Single span and simply supported end spans of multiple bays' 1. Open -web steel joists or steel beams supporting concrete slab, precast units, or metal decking Unrestrained 2. Concrete slabs, precast units, or metal decking Unrestrained B. Interior spans of multiple bays 1. Open -web steel joists, steel beams, or metal decking supporting continuous concrete slab Restrained 2. Open -web steel joists or steel beams, supporting precast units or metal decking Unrestrained 3. Gast -in -place concrete slab systems Restrained 4. Precast concrete where the potential thermal expansion is resisted by adjacent construction' Restrained II. Steel framing A. Steel beams welded, riveted, or bolted to the framing members Restrained B. All types of cast -in -place floor and roof systems (such as beam -and -slabs, flat slabs, pan joists, and waffle slabs) where the floor or roof system is secured to the framing members Restrained C. All types of prefabricated floor or roof systems where the structural members are secured to the framing members and the potential thermal expansion of the floor or roof system is resisted by the framing system or the adjoining floor or roof construction' Restrained Ill. Concrete framing A. Beams securely fastened to the framing members Restrained B. All types of cast -in -place floor or roof systems (such as beam -and -slabs, flat slabs, pan joists, and waffle slabs) where the floor system is cast with the framing members Restrained C. Interior and exterior spans of precast systems with cast -in -place joints resulting in restraint equivalent to that which would exist in condition III A. Restrained O. All types of prefabricated floor or roof systems where the structural members are secured to such systems and the potential thermal expansion of the floor or roof systems is resisted by the framing system or the adjoining floor or roof construction' Restrained IV. Wood Construction All types Unrestrained 'Floor and roof systems can be considered restrained when they are tied into walls with or without tie beams, the walls being designed and detailed to resist thermal thrust from the floor or roof system. 'For example, resistance to potential thermal expansion is considered to be achieved when: 1. Continuous structural concrete topping is used, 2. The space between the ends of precast units or between the ends of units and the vertical face of supports is tilled with concrete or mortar, or S. The space between the ends of precast units and the vertical faces of supports or between the ends of solid or hollow -core slab units does not exceed 0.25 percent of the length for normal weight concrete members or 0.1 percent of the length for structural lightweight concrete members. Reprinted with permission from the Annual Book of ASTM Standards Volume 4.07. Copyright ASTM, 1916 Race Street, Philadelphia, PA 19103 beams, the ability of roofs and floors to carry load is influenced by several factors in design. Tabulated values for concrete cover, similar to those for beams, exist for roof and floor slabs and are shown in Table 8. Columns The structural fire endurance of concrete columns is influenced primarily by the column size and the concrete aggregate type. The bases at present for column fire endurance design are tabulated minimum cover and column size requirements based on past ASTM E119 tests which were run to the structural failure end point. Further research on columns is being conducted presently at the laboratories of the National Research Council of Canada and the Portland Cement Associ- ation. Preliminary results indicate that current code provi- sions are conservative and that cover thickness is rela- tively unimportant. FACTORS INFLUENCING ENDURANCE OF CONCRETE AND MASONRY EXPOSED TO FIRE Three principal factors influence the fire endurance of concrete and masonry. These factors, thickness and aggregate type, thermal restraint conditions, and temper ature distribution through members are included in the code -approved methods for calculating fire resistance and need to be understood before attempting to carry out the calculations. Effect of Thickness and Aggregate Type The factors which determine the fire endurance of con- crete and masonry members or assemblies subject to the heat transmission end point criteria (walls, floors, roofs) are the thickness and the aggregate type of con- crete used. This can be seen clearly in Table 3, which shows that for a given aggregate type the length of time to reach a 250OF temperature rise on the unexposed surface increases as the thickness of the concrete increases. Table 3. Fire Endurances of Naturally Dried Specimens' Slab Thickness, Fire endurance, hr:min. Siliceous Carbonate _ Sanded expanded in. agora ate aggregate shale aggregate' 11h 0:18 0:1e 0:24 21k 0:35 0:41 0:54 4 1.16 1:27 2:16 5 2:01 2:17 3:00 6 2:50 3:16 4:55 7 3:57 4:31 — 'Times shown are times required to reach 250°F average temperature on unexposed surface. "Ith sand from Elgin, Illinois, replacing 60%(by absolute volume) of the fines. Examination of Table 3 also shows that lightweight aggregate concrete transmits heat more slowly than normal -weight concrete, resulting in longer fire endur- ances. As unit weight, determined by aggregate type, is reduced, resistance to heat transmission increases. Structural lightweight concretes use aggregate such as expanded shale, clay, and slate and have unit weights ranging from 100 Ibs per cu ft to about 120 Ibs per cu ft. Normal -weight concretes have unit weights ranging from 135 to 150 Ibs per cu ft. Normal -weight concretes utilize siliceous aggregates obtained from natural sand and gravel or carbonate aggregates such as limestone. Lightweight insulating concretes with unit weights of as low as 30 lb per cu ft are also available. Effect of Restraint of Members During Fire Loading Most cast -in -place reinforced concrete members are considered restrained. Precast or prestressed concrete members are more difficult to classify, and conditions which affect thermal restraint should be carefully exam- ined in every case involving a beam, floor, or roof assembly. The tabular methods contained within the model codes consider either fully restrained or fully unrestrained members subjected to ASTM E119 fire tests. In most cases the presence of restraint will enhance fire endurance. Table 2, which is part of Appendix X3 of ASTM E119 and is contained within the UL Fire Resistance Direc- tory, provides some criteria for identifying whether a given member or assembly is restrained or unrestrained, Temperature Distribution Within Concrete and Masonry Members and Assemblies In concrete and masonry, several factors influence temperature distribution through a member; primary are the shape or thickness of the member and the concrete aggregate type. Temperature distribution through or within the member during ASTM Ell firetesting is important in determining heat transmission rates in walls and floors and roofs and in determining steel and con- crete temperatures in beams, floors and roofs, and columns. PART 11 CODE -APPROVED METHODS OF CALCULATION The methods depicted in this portion of the report are empirical and tabular. As discussed, these procedures are accepted by the model codes to varying degrees. While the three model codes have adopted slightly dif- ferent language regarding analytical methods, the tech- nical bases for all code -approved analytical methods are set forth in references 1 and 2. It follows that most critical factors (wall thickness, concrete cover, and so forth) do not differ from code to code. To limit redundancy in tables and figures, various minor differences between the codes will be pointed out by footnotes. HEAT TRANSMISSION END POINT Solid Concrete Walls, Floors, and Roofs of Constant Thickness When considering flat, single-wythe concrete or masonry walls, floors, or roofs, heat transmission endurance peri- ods are based on the actual or equivalent thickness of the assembly in accordance with Fig. 2 (concrete) or Table 4 (masonry). When the building component in question is ribbed, tapered, undulating, or has hollow cores, an equivalent solid thickness must be determined. Equivalent thick- ness is the thickness obtained by considering the gross cross -sectional area of a wall minus the area of voids or undulations in hollow or ribbed sections, all divided by the width of the member. Calculation of equivalent thickness is outlined for several common concrete and masonry building components in Figs. 3, 4, and 5 and elsewhere within the text. Tapered Flanges Equivalent thickness for a concrete T-beam with tapered flanges is taken as the actual thickness of the flange measured at a distance of twice the minimum thickness or 6" from the end of the flange (whichever is less). This is shown in Fig. 3. e LL Panel mickness,in. Note: SBC and UBC specify concrete wall thickness using tables similar to Table 4; BOCA specifies references 1 and 2 when referring to wall thickness. Values shown in Fig. 2 are valid far all model codes. Fig. 2. Thickness of concrete required for fire endurances shown. Table 4. Minimum Equivalent Thickness in Inches of Load -Bearing Concrete Masonry Unit Wails for Fire -Resistance Ratings' A. SW 4 hr 3 hr 1 2 hr 1 hr Expanded slag or pumice aggregates 4.7 4.0 3.2 2.1 Expanded shale, clay, or slate aggregates 5.1 4.4 3.6 2.6 Limestone, cinders, or unexpanded slag aggregates 6.9 5.0 4.0 2.7 Calcareous gravel aggregates 6.2 5.3 4.2 2.8 Siliceous gravel aggregates 6.7 5.7 4.5 3.0 B. UBC' 4 hr 3 hr 2 hr / hr Expanded slag or pumice 4.7 4.0 3.2 2.1 Expanded clay, shale, or slate' 5.1 4.4 3.6 2.6 Limestone, cinders, or air-cooled slag 5.9 5.0 4.0 2.7 Calcareous or siliceous gravel 6.2 5.3 4.2 2.8 `Recommended for approval C. BOCA- 4 hr 3 hr 2 hr 1 hr Expanded slag or pumice 4.7 4.0 3.2 2.1 Expanded clay, shale, or slate 5.1 4.4 3.6 2.6 Limestone, cinders, or slag 5.9 5.0 4.0 2.7 Calcareous and siliceous gravel 6.2 1 5.3 1 4.2 1 2.8 'Fire ratings for thicknesses between tabulated values may be obtained by direct Interpolation. eSBC and UBC-Where all of the core spaces of hollow -core wall panels are filled with loos 4111 material such as expanded shale, clay or slag, or vermiculite or perlite, the fire -resistance rating of the wall Is the same as that of a solid wall of the same concrete type and of the same overall thickness. 'BOCA-Walla composed of hollow concrete masonry units having a nominal thickness of 8Inches or greater and having a fire -resistance rating of at least 2 hours shall be classified as 4 hours when the hollow spaces are completely filled with insulation, grout, or a dry granular material such as expanded slag, clay, shale. or sand. Determine thickness here 2/ or 6° whichever is less Fig. 3. Equivalent thickness of a tapered member. Ribbed Concrete Members For ribbed or undulating surfaces, calculation of equiv- alent thickness is based on the spacing of the stem components and minimum thickness of the flange. Cal- culation of the equivalent thickness i s determined based on the provisions shown in Fig. 4. For s > Q. the thickness to be used shall be t For s < 2t, the thickness to be used shall be to For 4t> s > 2t the thickness shall be t + s - 1) its - t) s = spacing of ribs or undulations t - minimum thickness to = equivalent thickness of the panel calculated as the net cross -sectional area of the panel divided by the width; not to exceed 2t y r v Note. Neglect shaded areas in - calculation of equivalent thickness + Fig. 4. Equivalent thickness of a ribbed or undulating section. Hollow -Core Concrete Planks The equivalent thickness (ted of hollow -core planks is obtained by the equation Anet _ teq width where Anal is the gross cross section (thickness X width) minus the area of cores. This is shown in Fig. 5. A„°, = area of gross cross section - area of cores A „er = 8 in. X 72 in. - 5 ( 7 (4)2 4 = 576 sq in. - 62.8 sq in.=/513.2 sq In. = 513 sc in. = 7 t in. t °q 13 �., _ 0000 Fig, 5. Typical hollow -core concrete plank. Concrete Masonry Block Hollow or solid concrete masonry units are available in nominal thicknesses of 2, 3, 4, 6, 6, 10, and 12 in with varying percentages of solid area. The equivalent thick- ness for hollow block can be calculated using a proce- dure similar to that for hollow -core slabs. Equivalent thick- ness for concrete masonry can be determined from the following equation: teQ = % solid X thickness The percent of solids in any given masonry unit can be obtained from the manufacturer. Once equivalent thick- ness is known, the fire -resistance rating of masonry walls can be determined from Table 4. See notes to Table 4 for each model code's provision regarding fire endurance of filled block. If 100%solid flat -sided con- crete masonry units are used, the equivalent thickness is the actual thickness. Brick The model code fire ratings based on E119 tests of load -bearing, solid or hollow, shale or clay brick walls of various thicknesses and varying finishes (plastered, unplastered) are shown in Table 5 A-C. The fire endur- ance of brick walls is dependent on brick thickness, type of members that frame into the walls (combustible or noncombustible), and finishes such as plaster. As with concrete and masonry walls, brick walls generally reach the heat transmission end point before failing structurally. Multi-Wythe Walls A multi-wythe wall (that is, a wall with more than one layer of material) has a greater fire -endurance period than a simple summation of fire -endurance periods of the various layers. An equation for determining esti- mated fire endurance of multi-wythe walls based on the heat transmission end point is where R=(R1o.59+R20.59. +Rnos9)1.7 Eq.1 R = total fire -endurance rating in minutes R1, etc. = fire endurance in minutes of each individual wythe (or component lamina) For example, two wythes—each rated at 1 hour (see Fig. 2: 3.2 in. carbonate aggregate and 2.7 in. lightweight aggregate concretes) —wilt give R = ( (60)d 59 + (60) c 59)" = 197 minutes (3 hours, 17 minutes) Graphical calculation is shown for this system in Fig. 6. The equation is not applicable in all cases and must be used keeping the following conditions in mind. 1. The fire endurances (determined in accordance with ASTM E119) of each wythe must be known. 2. The equation does not account for orientation of layering. It is known that if the more fire-resistant material is on the fire -exposed surface, a higher total rating would be obtained during actual testing than if the wythes were reversed. Table 5. Fire -Resistance Periods for Clay or Shale, Solid or Hollow Brick Walls A. SBC Fire-Reslstance Ratings for Load -Bearing Walls and Partitions (Minimum nominal thickness In Inches for fire -resistance ratings Indicated) Members framed into wall or partition Combustible None or Noncombustible Wall or partition assembly 4hr I 3hr 2hr 1hr 4hr 3hr 2hr 1hr Soiid-brick walls Solid (clay, shale, concrete, or sand -lime) —unplastered 12 12 8 8 8 8 8 OSU T-1971 T-1972 —clay or shale 6 4 Solid (as above) 'b" (1:3) sanded gypsum plastered on one side 12 (1) 8 or 12 (1)(2) 8 (1) 8 (1) 8 8 8 Solid (as above) 'h" (1:3) sanded gypsum plastered 12 8 or 12 8 8 8 8 on each side (2) Brick (clay or shale)-4"-thick units at least 75 percent solid backed with a hat -shaped metal furring channel %" thick formed from 0.021" sheet metal attached to the brick wall 5 on 24" centers with approved fasteners; and 11g" Type X gypsum wallboard attached to the metal furring strips with 1"-long Type S screws spaced 8" on center (1) Rating Is applicable only when plastered side of wall or partition Is on exposed side. (2) e" for sand -lime or concrete brick, or 12" for clay or shale brick (3-hour rating). B. UBC Rated Fire -Resistive Periods for Various Walls and Partitions Minimum finished thickness face-to-face° (in inches) Item 4 hr 3 hr 2 hr 1 hr Material number Construction 1 Solid units (at least 75 percent solid) 8 6 4 2 Solid units plastered each side with ib" gypsum or Portland cement plaster. 4y4 Portland cement plaster mixed 1.2'4 by weight, cement to sand 3 Hollow -brick units at least 71 percent solid' 8 4 Hollow -brick units at least 71 percent solid, plastered each side with %" gypsum 61: plaster' Brick of 5 Hollow (rowlock)2 12 1 8 clay or Hollow (rowlock) plastered each side with %" gypsum or Portland cement plaster. 9 shale 6 Portland cement plaster mixed 1:21h by weight, cement to sand' 7 Hollowcavlty wail consisting of two 4" clay brick units with air space between 10 B Hollow -brick units at least 60 percent solid, cells filled with perlite loose -fill 8 insulation 4"-thick units at least 75 percent solid backed with a hat -shaped metal furring 9 channel Y." thick formed from 0.021" sheet metal attached to the brick wall on 5 24" centers with approved fasteners; and '1h" Type X gypsum wallboard attached to the metal furring strips with 1"-long Type S screws spaced 8 inches on center 'Hollow -brick units 4-inch by 8-Inch by 12-Inch nominal with two Interior cells having a 1'Fi-Inch web thickness between cells and a ly'-inch-thick face shells. 'Rowlock design employs clay brick with all or part of bricks laid on edge with the bond broken vertically. C. BOCA Fire -Resistance Periods for Load -Bearing Clay and Shale Brick Wails' Ultimate fire -resistance period in hours Nominal wall Noncombustible members Combustible thick- Wall famed Into wall or no members framed ness. in. type framed -in members into wall Plaster Plaster Plaster on No on one on two No exposed plaster side' sidess plaster side' 4 Solid T'/4 1s/. 2'1h — — 8 Solid 5 6 7 2 21h 12 Solids 10 10 12 a 9 12 Solid' 12 13 15 — — 9 to 10 Cavity 5 6 7 2 2'1h 'BOCA specifies BIA "Building Code Requiements for Engineered Brick Masonry." Table 5C is a reprint from that series. aro achieve these ratings, each plastered wall face must have at least'h-in., 1:3 gypsum -sand plaster. 'Based on load failure. 'Based on temperature rise(for non -load -bearing walls). Graphical Method ' J Th..k.. of normal vrogMcancrne,in + Calculation Method 3.20" carbonate aggregate concrete from Fig. 2, R = 1.0 hr 2.70" sand -lightweight concrete from Fig. 2, R = 1.0 hr Rn,ei= ((60)0.5e+ (60)0.50)"a 197 minutes (3 hr, 17 minutes) Fig. 6. Fireendurance of mufti-wythe walls -graphical versus calculation method (based on fire exposure on normal weight concrete side of assembly). 3. The exponent 1.7 and its reciprocal 0.59 are average values which vary from material to material. The equation is generally accurate within ten percent. Graphical means of calculating multi-wythe fire resist- ance, as shown in Fig. 6, should be used when greater accuracy is required. Table 6 shows values for R059 to be used in the multi-wythe equation. Note that concrete masonry block and brick are not included. Ross values may be ob- tained for any wall tested per ASTM E 119 by simply raising the resistance, in minutes, to the 0.59 power. For example, from Fig. 2 it can be seen that 3.5 inches of siliceous aggregate concrete will provide one hour fire endurance, and (60)0.59 = 11.3. Referring to Table 6 we see that R0.59for 3.5 inches of siliceous aggregate con- crete is 11.3. To apply the multi-wythe equation to brick, masonry, and composite walls the resistance (R) values in min- utes for brick (Table 5) and masonry (Table 4) should be used. Sandwich Panel Wall Section Precast concrete panels consisting of a layer of foamed insulation between two layers (wythes) of concrete have become a popular method of providing energy -efficient walls. Foam insulation can be considered to have a fire -resistance rating (R) of 5 minutes if one inch of thicker (Re59 = 2.5 minutes). For thicknesses less than one Inch, the effect of the foam Insulation should nol be considered in calculating the panel fire endurance. Multicourse Concrete Floors and Roofs Calculations of heat transmission fire endurance of mul ticourse floors and roofs are similar to analysis of multi- wythe walls. Fig. 6 shows the required thickness of a siliceous or carbonate aggregate concrete base course and an overlay of sand -lightweight concrete required tc achieve fire endurances from one to four hours. Ratings shown are based on the heat transmission end point. Graphs such as Fig. 6 have been approved for analytical calculation of multicourse floor, roof, and wall fire endur- ance by all model codes. Reference t is an excellent source of this graphical data. STRUCTURAL END POINT Reinforced and Prestressed Concrete Beams Reinforced and prestressed concrete beam fire endur- ance is governed by the ability of the beam to carry structural loads. In addition, steel temperatures must in some cases be maintained below the ASTM El 191imits of 800°F for prestressing steel and 1100eF for reinforc- ing steel. Under the ASTM El 19 standard, beams can be tested for either restrained or unrestrained conditions. A summary of ASTM E119 conditions of acceptance and steel temperature criteria for beams follows: 1. Beams -tested restrained and used restrained. For individual restrained beams spaced more than 4 feet on center, the steel temperatures must be limited to below 800OF (prestressing) or 1100OF (reinforcing) for one hour or one-half the desired rat- ing period, whichever is greater. Table 6. Rnss9 Values for Various Thicknesses of Concrete Floors, Roofs, and Walls; Various Aggregate Types' Type of material Values of Rno � for use in Eq. 1 1'h In. 2 in. I 2'h in. 3 in. 31h in. 4 in. 4'h in. 5 in. 51h In. 6 in. 654 in. 7 in. Siliceous aggregate concrete 5.3 6.5 8.1 9.5 11.3 13.0 14.9 16A 18.6 20.7 22.8 25.1 Carbonate aggregate concrete 5.5 7.1 8.9 10.4 12.0 14.0 16.2 18.1 20.3 21.9 24.7 27.2"' Sand -lightweight concrete 6.5 8.2 10.5 12.8 15.5 18.1 20.7 23.3 26.d" 1° `e IN Lightweight concrete 6.6 8.8 11.2 13.7 16.5 19.1 21.9 24.7 27.0e I41 lu P1 Insulating conCrete11 9.3 13.3 16.6 18.3 23.1 26.51" 'e (`) "1 t" fO i° Air Space11 I - - - - - - - - - - - - ("All model codes recognize the use of the listed R„ae"values for concrete. To be used when calculating total resistance in minutes. 11Dry unit weight 35 pcf or less and consisting of cellular, perlite, or vermiculite concrete. p1The Rnass value for 1'h•inch to TA -inch air space is 3.3. The Rc059 value for 2'h-inch to 3'h-inch air space is 6.7. 1OThe fire -resistance rating for this thickness exceeds 4 hours. 8 2. Beams —tested in an unrestrained condition and used unrestrained. Steel temperature limits are waived, the beam is rated on its ability to carry the applied load. 3. Beams —tested in a restrained condition but used unrestrained. Steel temperatures in concrete beams must be maintained below the limits of 800OF for prestressing and 1100"F for reinforcing for the entire endurance period. Table 7. Minimum Cover In Inches for Reinforced and Prestressed Concrete Beams' The several different classifications for beams graph- ically illustrate the several conditions which influence beam fire endurance. Factors such as beam width and spacing, restraint conditions, and concrete cover are considered in Table 7. The tabulated cover require- ments in Table 7 will maintain steel temperatures below the ASTM E119 limits for the listed exposure times for shown restraint conditions, beam widths, and concrete aggregate type (if prestressed). A. Minimum Cover to Mein Reinforcing Bars for Reinforced Concrete Beams (Applicable to All Types of Structural Concrete)(" Restrained or unrestrained" Beam width"' (Inches) Cover thickness (inches) for fire -resistance rating 1hr 11hhr I 2hr 3hr 4hr Restrained 5 3/. 3/. 3/4 1f1 1ul1) Restrained 7 V. Y. V. V. 3/. Restrained > 10 3/4 i'. V. V. % Unrestrained 5 1'. 1 11/. — — Unrestrained 7 3K V. % 1% 3 Unrestrained > 10 Y. 3: y. 1 1V.. "'The cover for an individual reinforcing bar is the minimum thickness of concrete between the surface of the bar and the fire - exposed surface of the beam. For beams In which several bars are used, the cover is assumed to be the average of the minimum cover of the individual bars, where the minimum cover for corner bars used In the calculation shall be reduced to'h of the actual value. The cover for an Individual bar must be not less then'14 of the value given in Table 7A nor less than 4: inch. "'See Table 2 for guidance on restrained and unrestrained assemblies. Tabulated values for restrained assemblies apply to beams spaced 4feet on centers; for restrained beams spaced 4 feet or less on centers, minimum cover of 1: Inch is adequate for ratings of 4 hours or less. "'For beam widths between the tabulated values, the minimum cover thickness can be determined by direct interpolation. B. Minimum Cover for Prestressed Concrete Beams"' Restrained or unrestrained"' Concrete aggregate type Beam width' (inches) Cover thickness"' (inches) for fire -resistance rating 1 hr Ph hr 2 hr 3 hr 4 hr Restrained Carbonate or siliceous 8 11A 11h 1'h I./M 2'h'o Restrained Carbonate or siliceous > 12 11h 1'h 11h 11h 11,611, Restrained Sand -lightweight 8 1% 11h 11h 11/2 2'u Restrained Sand -lightweight > 12 1'1h 11h 11/2 11h 1%'" Unrestrained Carbonate or siliceous 8 1'h 1% 21h 5"' —. Unrestrained Carbonate or siliceous >12 11h 1'h 1'h 21h 3 Unrestrained Sand -lightweight 8 11h 1'h 2 34/. — Unrestrained Sand -lightweight > 12 11h 11h 1% 2 2'h "'Minimum cover to nonprestressed reinforcing in prestressed concrete beams shall be determined by values shown in Table 7A. For UBC jurisdictions, the cover requirements for reinforcing steel derived from calculation methods for determining fire endurance of structural members prescribed in Standard No. 43-9 of the Uniform Building Code shall not apply to precast prestressed single or double T units. Cover requirements for these members can be found in Table No. 43-A, items 30 and 31, of the UBC. '"See Table 2 for guidance on restrained and unrestrained assemblies. Tabulated values for restrained assemblies apply to beams more than 4 feet on center. "'For beam width between 8 and 12 inches, minimum cover thickness can be determined by direct Interpolation. "'The cover for an Individual tendon is the minimum thickness of concrete between the surface of the tendon and the fire -exposed surface of the beam, except that for ungrouted ducts the assumed cover thickness is the minimum thickness of concrete between the surface of the duct and the surface of the beam. For beams in which several tendons are used, the cover Is assumed to be the average of the minimum cover of the Individual tendons. The cover for any Individual tendon must be not less than one-half of the value given in Table 7B nor less than 1 inch. "'Not practical for 8-inch-wide beam, but shown for purposes of interpolation. 'UBC (Standard Section 43-9) and SBC (Appendix P) both contain the tabulated values shown; B/NBC refers to references 1 and 2 of this report. Based on technical information In references 1 and 2. B/NBC jurisdictions may accept values shown in Table 7A and B. Reinforced or Prestressed Concrete Floor and Root Slabs As previously discussed, the fire endurance of floor and roof slabs is based on either the heat transmission or structural failure end point. It is for this reason that code - approved empirical methods require both a minimum slab thickness to limit heat transmission and a minimum amount of concrete cover to limit steel temperatures. As discussed earlier, the fire endurance of reinforced or prestressed concrete slabs is dependent upon several factors, such as type of aggregate in the concrete, con- crete cover, and restraint of thermal expansion. The values for slabs shown in Table 8 represent min- imum required slab thickness and concrete cover requirements for reinforced or prestressed slabs for var- ious aggregate type concretes in restrained or unre- strained conditions. The tabularfire endurances listed in Table 8 are based on examination of past ASTM El 19 test results of slabs with similar cover, restraint condi- tions, and concrete aggregate type. The specified cover for unrestrained assemblieswill maintain steeltempera- tures below the specified limits of 800° F for prestressing and 1100e F for reinforcing steel. Again, Table 2 should be referenced when determining whether a floor or roof is restrained or unrestrained. Concrete Columns Fire endurance of concrete columns is governed under ASTM El19 by their ability to carry the applied load under fi retesting. The endurance is affected primarily by the size of the column and aggregate type. A summary of the tabular code -approved minimum column dimen- sions and concrete cover requirements is shown in Table 9. Table 8. Minimum Slab and Concrete Cover Thickness In Inches for Listed Fire Resistance of Reinforced Concrete Floors and Roots' A. Minimum Slab Thickness for Concrete Floors or Roofs' Concrete aggregate type Minimum slab thickness (inches) for fire-resistrance rating ihr 11/2 hr 2hr 1 3hr I 4hr Siliceous 3.5 4.3 5.0 6.2 7.0 Carbonate 3.2 4.0 4.6 5.7 6.6 Sand -lightweight 2.7 3.3 3a 4.6 5.4 Lightweight 2.5 3.1 3.6 4.4 5.1 9. Cover Thickness for Reinforced Concrete Floor or Roof Slabs' Thickness of cover (inches) for fire -resistance rating Restrained' Unrestrained' Concrete aggregate type 1hr 1'h hr 2hr 3hr 1hr 11h hr 2hr 3hr Siliceous iL 3/4 'A Y4 141 % 1 1N Carbonate 3'. 1'4 V V. '/. V4 y4 1% Sand -lightweight % 3/r % Y. % '/. V44 1'/4 Lightweight b'. 3/4 N. 'A % % '/i 11/4 C. Cover Thickness for Prestressed Concrete Floor or Root Slabs' Thickness of cover (inches) for fire -resistance rating Restrained' Unrestrained' Concrete aggregate type 1hr 41h hr 2hr 3hr 1hr 1'h hr 2hr I 3hr Siliceous 1/4 Y. V. % 1'h 1'h 1% 2% Carbonate V. % 3'. % 1 1% 1% 21h Sand -lightweight V. 1'4 % 14 1 1% 11/2 2 Lightweight % $'4 Y. V. 1 1% 1% 2 'Both the UBC (Standard Section 43-9) and SBC (Appendix P) contain the tabulated values shown in Table 8; B/NBC refers to references 1 and 2 of this report. Based on technical information in References 1 and 2, B/NBC jurisdictions may accept values shown in Table 8. +The minimum thickness of concrete cover to the positive moment reinforcement is given In Table 8B for reinforced concrete and Table actor prestressed concrete. Table 8 is applicable for solid or hollow - core one-way or two-way slabs with flat undersurfaces. Slabs may be cast -in -place or precast. For precast prestressed concrete not covered elsewhere, the procedures contained in PCI Design for Fire Resistance of Precast Prestressed Concrete shall be acceptable. 'See Table 3 for guidance on restrained and unrestrained assemblies. 10 Table 9. Minimum Concrete Column Size and Concrete Cover* Concrete aggregate type Minimum column dimension (Inches) for fire-resistrance 1hr 1'hhr I 2hr _rating 3hr 4hr Siliceous 8 8 10 12 14 Carbonate 8 8 10 12 14 Sand -lightweight a 8 9 10.5 12 Minimum Cover for Reinforced Concrete Columns.The minimum cover to the main reinforcement in columns for tire -resistance ratings of one hour, one and one-half hours, two hours, and three hours shall be 1'Fi Inches; for four-hour rating, the minimum cover to the mein reinforcement shall be 2 inches for siliceous aggregate concrete and 1,h inches for carbonate aggregate concrete or sand -lightweight concrete. 'UBC (Standard Section 43-9) and SBC (Appendix P) contain provisions as shown in Table 9. B/NBC refers to references 1 and 2 of this Report which contain similar provisions. CONCLUSION Calculation of fire endurance of concrete and masonry members has progressed from pure research to practi- cal structural design applications. Further refinements of analytical methods are going on now, aided In great part by computer simulations of concrete and masonry performance under fire -test conditions. The information contained in this report scratches the surface on the topic of analytical and empirical design, The practicing structural engineer will find references 1, 2, and 3 excellent sources of additional information on the rational methods for calculating fire resistance. The engineer, architect, or building official will find this a handy and usable guide in assessing concrete and masonry requirements with regard to fire endurance. Calculation procedures provide a viable timesaving and cost saving means of determining a member's fire endurance without running full scale ASTM El19 fire tests. Along with savings of time and money, the building official, architect, or engineer will have a much clearer concept of how certain variables affect fire endurance if analytical procedures are utilized. REFERENCES 1. Reinforced Concrete Fire Resistance, Concrete Rein- forcing Steel Institute, Schaumburg, Illinois, 1980. 2. Gustaferro, A. H. and Martin, L. D., Design for Fire Resistance of Precast Prestressed Concrete, Pre- stressed Concrete Institute, Chicago, Illinois, 1977. 3. Guide for Determining the Fire Endurance of Con- crete Elements, 216R-81, American Concrete Insti- tute, Detroit, Michigan, 1981. 4. Fire Safety with Concrete Masonry, NCMA-TEK 35-B, National Concrete Masonry Association, Herndon, Virginia, 1984. 5. Fire Resistance, BIA Technical Notes on Brick Con- struction No. 16, Brick Institute of America, October 1974. Organizations represented on the CONCRETE AND MASONRY INDUSTRY FIRESAFETY COMMITTEE BIA Brick Institute of America CRSt Concrete Reinforcing Steel Institute ESCSI Expanded Shale Gayand Slate Institute NCMA National Concrete Masonry Association NRMCA National Ready Mixed Concrete Association PCA Portland Cement Association PCI Prestressed Concrete institute This publication is intended for the use of professional personnel competent to evaluate the significance and limitations of its contents and who will accept responsibility for the application of the material it contains. The Concrete and Masonry Industry Firesafety Committee disclaims any and all responsibility for application of the stated princi- ples or for the accuracy of the sources other than work performed or information developed by the Committee. in Canada, building codes require that tire -resistance ratings be determined either on the basis of results of tests conducted in accord. ance with ULC S101, "Standard Methods of Fire Endurance Tests of Building Construction and Materials" or on the basis of Chapter 2, "Fire Performance Ratings," of the Supplement to the NBC. While the general principles set forth in this Fire Protection Planning Report are fully valid, in that they are based on materials properties and structural engineering procedures, users of this Report are cautioned that, in Canada, fire -resistance ratings should be determined strictly in accordance with applicable building -code requirements 11 BEAM -SLAB EXAMPLE The cast -in -place reinforced concrete beam and slab shown in Fig. 7 form a floor system in a multistory occu- pancy of Type I construction (SBC). Assume this assembly is required by code to have 3 hours of fire resistance. Can it attain this? If not, how can the fire resistance be increased to 3 hours? 4' 0° I Q _N TyTrp,coier 5� o�ccl Fig. 7. Siliceous aggregate cast -in -place —restrained. Solution Beam -slab systems must satisfy both heat transmission and structural failure end points. The member shown in Fig. 7 is considered restrained due to its being cast -in - place with framing members. HEAT TRANSMISSION END POINT Referring to Fig. 4, the equivalent thickness is deter- mined using the three equations comparing s (stem spacing) and t (slab thickness). Replacing 4'-0" for s, and 4'/2" for t, s > 4t. Therefore tq = t = 4'/2". The required slab thickness from Table 8A for a three- hour fire -resistance rating is 6.2 inches; the 4.5 inches will provide between one -and -a -half and two hours re- sistance to heat transmission to the unexposed surface, not three hours as required. STRUCTURAL END POINT Slab. For many cast -in -place concrete slabs, the struc- tural cover exceeds cover required to achieve fire re- sistance. This is clearly the case with the example 2% inches cover versus 3/4 inches required by Table 8B for three hours fire resistance. Beam. Table 7A, for reinforced concrete beams, speci- fies 1 inch of concrete cover in 5-inch-wide restrained beams to attain three hours fire resistance. Note that the example beams are spaced 4 feet center to center. Footnote one states that for restrained beams spaced 4 feet or less on centers, the cover can be reduced to a minimum of 3/4 inches for four-hour ratings or less. The 1'IlHir ch cover provided clearly satisfies the code require- ments for 3 hours fire resistance. Conclusion In order to attain three hours fire resistance, the slab must be made more resistant to heat transmission. The steel cover requirements for three hours structural fire resistance in both the slab and the beam stem are satisfied. Fig. 8. Siliceous aggregate cast -in -place —restrained with 1'k" lightweight concrete topping. In discussing multi-wythe (multilayer) walls and floors earlier in the report, it was shown that significant resistance to heat transmission could be attained by considering the effect of layering of materials. This can be done using Eq. 1 or graphical methods. In this example problem, referring to Fig. 9, a 4'/2-inch base slab of siliceous aggregate with approximately 1'/2 inches of sand -lightweight concrete topping will provide the additional required resistance to heat transmission to attain three hours fire resistance. Checking Fig. 9 against Eq. 1, the 4'/2" of siliceous - aggregate concrete base slab has 1 hour, 36 minutes fire resistance (Fig. 2 or Table 8A). Fig. 2 shows that 1'/2 inches of sand -lightweight topping will provide approxi- mately 24 minutes resistance to heat transmission. Using Eq. 1, R = (R O.59 + R20.59)17 R = ((96)059 } (24)0.59)1•7 = 181 minutes (3 hours, 1 minute) Therefore the slab system shown in Fig. Bwill provide three hours fire resistance if a 1'/2-inch topping of sand - lightweight concrete is applied. Thickness of normal weight concrete, In. Fig. 9. Graphical solution of multi-wythe fire endurance. Concrete and Masonry Industry Firesafety Committee 5420 Old Orchard Road, Skokie, Illinois 60077-4321 SR267.01 B Printed in U.S.A. ERRATA SHEET Fire Protection Planning Report Number 13 (SR267B) Analytical Methods of Determining Fire Endurance of Concrete and Masonry Members —Model Code Approved Procedures PLEASE NOTE THE FOLLOWING ERRATA: CORRECTED MATERIAL IS UNDERLINED (1) Page S, Table 6, Footnote 3 should read: (3) The R,'"value for one V - to 3!6-inch air space is 3.3. The R 059value for two V2- to 3�/z-inch air spaces is 6.7. (Corrected on reprints.) (2) Page 9, Table 7A, Footnote 2 should read: (2) See Table 2 for guidance on restrained and unrestrained assemblies. Tabulated values for restrained assemblies apply to beams spaced more than 4 feet on centers; for restrained beams spaced 4 feet or less on centers, minimum cover of 3/ inch is adequate for ratings of 4 hours or less. (3) Page 9, Table 7B, Footnote 4 should read: (4) The cover for an individual tendon is the minimum thickness of concrete between the surface of the tendon and the fire -exposed surface of the beam, except that for ungrouted ducts the assumed cover thickness is the minimum thickness of concrete between the surface of the duct and the surface of the beam. For beams in which several tendons are used, the cover is assumed to be the average of the minimum cover of the individual tendons, where the minimum cover for corner tendons used in the calculation shall be reduced to one-half the actual value. The cover for any individual tendon must be not less than one-half of the value given in Table 7B nor less than I inch.