Composite Steel Floor Deck-Slabs

Transcription

1 AMERICAN NATIONAL STANDARDS / STEEL DECK C Standard for Composite Steel Floor Dek-Slabs opyright 2017 steel dek institute

2 1. General AMERICAN NATIONAL STANDARDS / STEEL DECK 1.1 Sope: A. This Standard for Composite Steel Floor Dek-Slabs, hereafter referred to as the Standard, shall govern the materials, design, and eretion of omposite onrete slabs utilizing old formed steel dek funtioning as a permanent form and as reinforement for positive moment in floor and roof appliations in buildings and similar strutures. B. The Appendies shall be part of the Standard. C. The User Notes and Commentary shall not be part of the Standard. User Note: User Notes and Commentary are intended to provide pratial guidane in the use and appliation of this Standard. D. Where the Standard refers to designer, this shall mean the entity that is responsible to the Owner for the overall strutural design of the projet, inluding the steel dek. User Note: This is usually the Strutural Engineer of Reord. E. Equations that appear in this Standard are ompatible with the US Customary System (USCS) of units. However, any onsistent system of units shall be permitted to be used. SI units or equations shown in parenthesis in this Standard are for information only and are not part of this Standard. User Note: The USCS is also referred to as English Units or the inh-pound system. F. Terms not defined in this Standard, AISI S100 or AISI/AISC shall have the ordinary aepted meaning for the ontext for whih they are intended. G. It shall be permitted to speify dek base steel thikness either by dimensional thikness, or by gage when the relationship of base steel thikness to gage has been defined by the dek manufaturer. However, for the purpose of design, the dimensional thikness shall be used. User Note: Both AISI and SDI now speify steel thikness in terms of design thikness in lieu of gage thikness. Gage thiknesses, however, are still ommonly referred to in the metal dek industry. Table UN-1.1 shows ommon gages and orresponding unoated design and minimum steel thiknesses. Table UN-1.1 Gage No. Design Thikness Minimum Thikness 1 in. mm. in. mm Minimum delivered thikness is 95% of the design thikness. 1

3 AMERICAN NATIONAL STANDARDS / STEEL DECK H. Exept as speifially required by this Standard, ACI 318 shall not be appliable to the design or onstrution of omposite steel dek-slabs. User Note: Refer to Setion of ACI Referene Codes, Standards, and Douments: : A. Codes and Standards: The following douments or portions thereof are referened in this Standard and shall be onsidered part of the requirements of this Standard. Where these douments onflit with this Standard, the requirements of this Standard shall ontrol: 1. Amerian Conrete Institute (ACI) a. ACI , Building Code Requirements for Strutural Conrete 2. Amerian Iron and Steel Institute (AISI) a. AISI S100-16, North Amerian Speifiation for the Design of Cold- Formed Steel Strutural Members. b. AISI S310-16, North Amerian Standard for the Design of Profiled Steel Diaphragm Panels.. AISI S905-13, Test Methods for Mehanially Fastened Cold-Formed Steel Connetions d. AISI/AISC, Standard Definitions for Use in the Design of Steel Strutures, 2007 edition 3. Amerian Institute of Steel Constrution (AISC) a. ANSI/AISC , Speifiation for Strutural Steel Buildings 4. Amerian Soiety for Testing and Materials (ASTM) a. ASTM A820 / A820M 11, Standard Speifiation for Steel Fibers for Fiber-Reinfored Conrete b. ASTM A1008 / A1008M - 15, Standard Speifiation for Steel, Sheet, Cold-Rolled, Carbon, Strutural, High-Strength Low-Alloy, High- Strength Low-Alloy with Improved Formability, Solution Hardened, and Bake Hardenable. ASTM C1116 / C1116M - 10a(2015) Standard Speifiation for Fiber- Reinfored Conrete d. ASTM D7508 / D7508M - 10 Standard Speifiation for Polyolefin Chopped Strands for Use in Conrete 5. Amerian Soiety of Civil Engineers (ASCE) a. SEI/ASCE 7-16, Minimum Design Loads for Buildings and Other Strutures 6. Amerian Welding Soiety (AWS) a. AWS D1.1:2015, Strutural Welding Code-Steel b. AWS D1.3:2008, Strutural Welding Code-Sheet Steel 7. Steel Dek Institute (SDI) a. SDI-T-CD-2017, Test Standard for Composite Steel Dek-Slabs 2

4 AMERICAN NATIONAL STANDARDS / STEEL DECK Commentary: The following douments are referened within the Commentary and User Notes: 1. Amerian Assoiation of State Highway and Transportation Offiials (AASHTO) a. AASHTO LRFD Bridge Design Speifiations, Customary U.S. Units, 7th Edition, with 2015 Interim Revisions 2. Amerian Conrete Institute (ACI) a. ACI 215R-92, Considerations for Design of Conrete Strutures Subjeted to Fatigue Loading b. ACI 302.1R-04, Guide for Conrete Floor and Slab Constrution. ACI 224.1R-07, Causes, Evaluation, and Repair of Craks in Conrete Strutures d. ACI , Building Code Requirements for Strutural Conrete e. ACI 544.3R-08, Guide for the Speifiation, Proportioning and Prodution of Fiber Reinfored Conrete f. ACI Conrete Terminology, 3. Amerian Institute of Steel Constrution (AISC) a. AISC Design Guide No. 11, Floor Vibrations Due to Human Ativity, 1997 b. AISC Design Guide No. 18, Steel-Framed Open-Dek Parking Strutures, ANSI/AISC , Speifiation for Strutural Steel Buildings 4. Amerian Iron and Steel Institute (AISI) a. AISI S100-16, North Amerian Speifiation for the Design of Cold- Formed Steel Strutural Members. 5. Amerian Soiety for Testing and Materials (ASTM) a. ASTM A653 / A653M - 15 Standard Speifiation for Steel Sheet, Zin-Coated (Galvanized) or Zin-Iron Alloy-Coated (Galvannealed) by the Hot-Dip Proess b. ASTM A1008 / A1008M - 15, Standard Speifiation for Steel, Sheet, Cold-Rolled, Carbon, Strutural, High-Strength Low-Alloy, High- Strength Low-Alloy with Improved Formability, Solution Hardened, and Bake Hardenable. ASTM E119-14, Standard Test Methods for Fire Tests of Building Constrution and Materials 6. Steel Dek Institute (SDI) a. SDI COSP-2017, Code of Standard Pratie. b. SDI-DDM, Diaphragm Design Manual, 4th Edition.. SDI FDDM, Floor Dek Design Manual, 1st Edition. d. SDI-MOC, Manual of Constrution with Steel Dek, 3rd Edition e. SDI Position Statement Use of Composite Steel Floor Dek in Parking Garages. 7. Underwriters Laboratories (UL) a. Fire Resistane Diretory 3

5 AMERICAN NATIONAL STANDARDS / STEEL DECK 1.3 Constrution Douments: The onstrution douments shall desribe the omposite slabs that are to be onstruted and shall inlude not less than the following information: A. Loads 1. Composite slab loads as required by the appliable building ode. Where appliable, load information shall inlude onentrated loads. 2. Assumed onstrution phase loads. B. Strutural framing plans for all omposite slabs showing the size, loation and type of all dek supports. C. Dek and Dek Attahment 1. Depth, type (profile), and design thikness. 2. Dek material (inluding yield strength) and dek finish, 3. Dek attahment type, spaing, and details. D. Conrete and Reinforing 1. Speified onrete strength, f 2. Speified onrete density (and tolerane if required for fire rating assembly) 3. Speified strength or grade of reinforing steel or welded wire reinforement (if used) 4. Size, extent and loation of all reinforement (if used) 5. Slab thiknesses (and tolerane if required for fire rating assembly) 6. Disontinuous fiber reinforement material, type and dosage (if used). 2. Produts 2.1 Material: User Note: The following is an example of a omposite slab as it ould be speified on the ontrat drawings: Composite slab shall onsist of 1-1/2 inh deep G-60 galvanized omposite steel dek, design thikness inh (20 gage), Fy = 50 ksi (Type XX by YY, In or approved equivalent) with 3 inh thik, 3000 psi, normalweight onrete topping (total thikness = 4-1/2 inhes) reinfored with XXX. Dek shall be attahed to supporting framing using #12 srews in a 36/7 pattern. (4) #10 sidelap srews shall be installed per dek span." A. Sheet steel for dek shall onform to AISI S100, Setion A3, as modified in Setion 2.1.C. User Note: AISI S100, Setion A3.1 notes an exeption that "For steels used in omposite slabs, the requirements of SDI-C shall be followed exlusively." The intention of this exeption is to permit that the requirements of Setions 2.1.C.2 and 2.1.C.3 shall be followed regarding limits on design yield stress and dutility. B. Sheet steel for aessories that arry defined loads shall onform to AISI S100, Setion A3. Sheet steel for non-strutural aessories that do not arry defined loads shall be permitted to be any steel that is adequate for the proposed appliation. 4

6 AMERICAN NATIONAL STANDARDS / STEEL DECK C. All sheet steel used for dek or aessories that arry defined loads shall have a minimum speified yield stress that meets or exeeds 33 ksi (230 Mpa). 1 For the ase where the steel dek ats as a form, design yield and tensile stresses shall be determined in aordane with AISI S100, Setion A3. 2. For the ase where the steel dek ats as tensile reinforement for the omposite dek-slab, the steel shall onform to AISI S100, Setion A3. When the dutility of the steel measured over a two-inh (50 mm) gage length is 10% or greater, the maximum design yield stress shall not exeed the lesser of 50 ksi (345 Mpa) or Fy. When the dutility of the steel measured over a two-inh (50 mm) gage length is less than 10%, the maximum design yield stress shall not exeed the lesser of 50 ksi (345 Mpa) or 0.75 Fy. 3. When the dutility of the steel used for dek, measured over a two-inh (50 mm) gage length, is less than 10%, the ability of the steel to be formed without raking or splitting shall be demonstrated. Commentary: Most steel dek is manufatured from steel onforming to ASTM A1008 /A1008M, Strutural Sheet for unoated or unoated top/painted bottom dek or from ASTM A653 / A653M, Strutural Sheet for galvanized dek. In most ases the designer will hoose one finish or the other. However, both types of finish may be used on a projet, in whih ase the designer must indiate on the plans and projet speifiations the areas in whih eah is used. (Refer to Setion 2.3 of this Standard). Stainless steel is not reommended due to the lak of available performane data. D. Conrete and Reinforement: 1. Conrete plaed on steel dek shall onform to ACI 318, Chapter 19, exept as modified by Setions 2.1.D.2 and 2.1.D The speified onrete ompressive strength shall not be less than 3000 psi (21 MPa). The maximum ompressive strength used to alulate the strength of the omposite dek-slab shall not exeed 6000 psi (42 MPa). User Note: Load tables and labeled fire resistant rated assemblies may require onrete ompressive strengths in exess of 3000 psi. The average ompressive strength of the onrete may exeed 6000 psi, but a maximum strength of 6000 psi is to be used in alulating the strength of the omposite dek-slab. 3. Admixtures ontaining hloride salts or other substanes that are orrosive or otherwise deleterious to the steel dek and embedded items shall not be permitted. 4. Steel Reinforing shall onform to ACI 318, Setion Disontinuous fiber reinforement shall onform to the following: a. Steel fibers: ASTM A820. b. Marosyntheti fibers: ASTM D Tolerane of Delivered Material: A. The minimum unoated steel thikness as delivered to the job site shall not at any loation be less than 95% of the design thikness, however lesser thiknesses shall be permitted at bends, suh as orners, due to old-forming effets. User Note: The minimum delivered thikness is in aordane with AISI S100. 5

7 AMERICAN NATIONAL STANDARDS / STEEL DECK B. Panel length shall be no less than ½ inh (13 mm) shorter than the speified length nor greater than ½ inh (13 mm) longer than the speified length for single span or butted end dek. Panel length shall be no less than ½ inh (13 mm) shorter than the speified length for lapped end dek. User Note: No restrition is plaed on over length panels in lapped appliations beause there is no adverse onsequene in this appliation. C. Panel over width shall be no less than 3/8 inh (10 mm) less than the speified panel width, nor more than 3/4 inh (19 mm) greater than the speified width. D. Panel amber and/or sweep shall not be greater than 1/4 inh in a 10 foot length (6 mm in 3 m). E. Panel end out of square shall not exeed 1/8 inh per foot of panel width (10 mm per m). F. Embossments (if used) shall not be less than 90% of the design embossment depth. 2.3 Finish: A. The finish on the steel dek shall be speified by the designer. B. Galvanizing or other metalli oatings (if speified by the designer) shall onform to the requirements of the appliable steels in AISI S100, Setion A3. User Note: The most ommonly speified galvanized sheet steel is ASTM A653 / A653M. C. A shop oat of primer paint (bottom side only) shall be applied to steel sheet if speified by the designer. Commentary: The finish on the steel omposite dek must be speified by the designer and be suitable for the environment to whih the dek is exposed within the finished struture. Beause the omposite dek is the positive bending reinforement for the slab, its servie life should at least be equal to the design servie life of the struture. Zin-Aluminum finishes are not reommended. When omposite dek with an unpainted top and painted bottom is used, the primer oat is intended to protet the steel for only a short period of exposure in ordinary atmospheri onditions and shall be onsidered an impermanent and provisional oating. In highly orrosive or hemial atmospheres or where reative materials ould be in ontat with the steel dek, speial are in speifying the finish should be used, whih ould inlude speialized oatings or materials. If speifying painted dek in areas that require spray-on fireproofing, the paint must be permitted by the appliable fire rated assembly. Not all paints are approved for fire rated assemblies. This requirement must be learly alled out in the ontrat douments. In general, there are three types of fire resistive assemblies; those ahieving the fire resistane by membrane protetion, diret applied protetion, or with an unproteted assembly. Of these three, only the systems that utilize diret applied protetion are onerned with the finish of the steel dek. In these systems, the finish of the steel dek an be the fator that governs the fire resistane rating that is ahieved. In assemblies with diret applied fire protetion the finish (paint) is ritial. 6

8 AMERICAN NATIONAL STANDARDS / STEEL DECK In the Underwriters Laboratories Fire Resistane Diretory, some dek manufaturing ompanies have steel dek units that are lassified in some of the D700, D800, and D900-series onrete and steel floor units. These lassified dek units (Classified Steel Floor and Form Units) are shown as having a galvanized finish or a phosphatized/painted finish. These lassified dek units have been evaluated for use in these speifi designs and found aeptable. 2.4 Design: A. Dek as a form 1. Design by either Allowable Strength Design (ASD) or Load and Resistane Fator Design (LRFD) shall be permitted. The setion properties and allowable strength (ASD) or design strength (LRFD) for the steel dek shall be omputed in aordane with AISI S Dek shall be evaluated for strength under the following load ombinations: a. Allowable Strength Design wd + wdd + wl (Eq ) wd + wdd + Pl (Eq ) wdd + wdl (Eq ) Where: wd = dead weight of onrete wdd = dead weight of the steel dek wl = uniform onstrution live load (ombined with fluid onrete) not less than 20 psf (0.96 kpa) wdl = uniform onstrution live load (ombined with bare dek), not less than 50 psf (2.40 kpa) Pl = onentrated onstrution live load per unit width of dek setion, 150 pounds on a 1 foot width (2.19 kn on a 1 meter width) User Note: The uniform onstrution live load of 20 psf is onsidered adequate for typial onstrution appliations that onsist of onrete transport and plaement by hose and onrete finishing using hand tools. The designer typially has little ontrol over means-and-methods of onstrution, and should bring to the attention of the onstrutor that bulk dumping of onrete using bukets, hutes, or handarts, or the use of heavier motorized finishing equipment suh as power sreeds, may require design of the dek as a form using uniform onstrution live loads, wl,of 50 psf or greater. Setion A1.3 requires that the designer inlude the assumed onstrution loads in the onstrution douments and it is suggested that the onstrutions douments require verifiation of adequay by the onstrutor. User Note: The designer should aount for additional loads attributable to onrete ponding due to defletions of the strutural system, inluding dek and support framing. See SDI-FDDM for additional information. 7

9 AMERICAN NATIONAL STANDARDS / STEEL DECK b. Load and Resistane Fator Design 1.6wd + 1.2wdd + 1.4wl (Eq ) 1.6wd + 1.2wdd + 1.4Pl (Eq ) 1.2wdd + 1.4wdl (Eq ) Commentary: The load fator used for the dead weight of the onrete is 1.6 beause of delivering methods and an individual sheet an be subjeted to this load. The use of a load fator of 1.4 for onstrution load in LRFD design is alibrated to provide equivalent design results in ASD design. Refer to the ommentary of AISI S100 for additional information. 3. Cantilever spans shall be evaluated for strength under the following load ombinations: a. Allowable Strength Design: Equations and shall be applied to both the antilever span and the adjaent span. The onentrated onstrution live load (Pl) shall be applied at the end of the antilever. b. Load and Resistane Fator Design: Equations and shall be applied to both the antilever span and the adjaent span. The onentrated onstrution live load (Pl) shall be applied at the end of the antilever. 4. Speial loading onsiderations: a. The speified onstrution live loads shall be inreased when required by the onstrution operations. b. Loads shall be applied in a sequene that simulates the plaement of the onrete, in aordane with Appendix 1. Rational analysis shall be permitted to be used for developing shear and moment diagrams and alulating defletions for non-uniform spans. Commentary: The loading shown in Figure 1 of Appendix 1 is representative of the sequential loading of fresh onrete on the dek. The 150 pound per foot of width (2.19 kn per 1 m of width) load is the equivalent of distributing a 300 pound (1.33 kn) worker over a 2 foot (600 mm) width. Experiene has shown this to be a onservative distribution. Single span dek onditions have no redundany beause they are statially determinate, as opposed to multi-span onditions that are statially indeterminate. Beause of this lak of redundany, additional onsideration should be given to proper speifiation of onstrution live and dead loads. Allowable onstrution spans for single-span dek may be shorter than for multi-span appliations, and the designer must onsider this in loations where it is impossible to install the dek in a multi-span ondition, suh as between stair and elevator towers. Whenever possible, the dek should be designed as a multi-span system that does not require shoring during onrete plaement. 8

10 AMERICAN NATIONAL STANDARDS / STEEL DECK The speified onstrution live loads reflet nominal loads from workers and tools and do not inlude loads of equipment suh as laser sreeds or power trowels nor additional onrete weight due to ponding. If antiipated onstrution ativities inlude these additional loads, they should be onsidered in the design. 5. Dek Defletion a. Calulated defletions of the dek as a form shall be based on the load of the onrete as determined by the design slab thikness and the selfweight of the steel dek, uniformly loaded on all spans. Defletions shall be limited to the lesser of 1/180 of the lear span or 3/4 inh (19 mm). Calulated defletions shall be relative to supporting members. b. The defletion of antilevered dek as a form, as determined by slab thikness and self-weight of the steel dek, shall not exeed a/90, where a is the antilever length, nor 3/4 inhes (19 mm). Commentary: The defletion alulations do not take into aount onstrution loads beause these are onsidered to be temporary loads. The dek is designed to always be in the elasti range, so removal of temporary loads will allow the dek to reover, unless onstrution overloads ause the stress in the dek to exeed the elasti limits of the dek. The supporting strutural steel also deflets under the loading of the onrete. The designer is urged to hek the defletion of the total system. Typial load tables are based on uniform slab thikness. If the designer wants to inlude additional onrete loading on the dek beause of frame defletion, the additional load should be shown on the design drawings or stated in the dek setion of the ontrat douments. 6. Minimum Bearing and Edge Distane: Minimum bearing lengths and fastener edge distanes shall be determined in aordane with AISI S100. User Note: Figure 2 in Appendix 1 indiates support reations. The designer should hek the dek web rippling apaity based on available bearing length. The dek should be adequately attahed to the struture to prevent the dek from slipping off the supporting struture. 7. Diaphragm Shear Capaity: Diaphragm strength and stiffness shall be determined utilizing the bare steel dek apaity without onrete in aordane with AISI S310. User Note: SDI-DDM ontains diaphragm load tables that omply with AISI S Connetions: Dek shall be attahed to supports to resist loads and to provide strutural stability for the supporting member. Connetions shall be designed in aordane with AISI S100 or strengths shall be determined by testing in aordane with AISI S905. Tests shall be representative of the design. When tests are used and the design allows either end laps or single thikness onditions, both onditions shall be tested. 9

11 AMERICAN NATIONAL STANDARDS / STEEL DECK B. Dek and Conrete as a Composite Slab: 1. Design by either Allowable Strength Design (ASD) or Load and Resistane Fator Design (LRFD) shall be permitted. Commentary: The ASD Fator of Safety is alibrated to the LRFD resistane fator at a live to dead load ratio of 3 to 1, whih is a reasonable load ratio for omposite dek slabs and mathes the ratio used in the AISC 360 Standard. 2. Flexural Resistane: Flexural resistane of the omposite dek-slab shall be determined in aordane with one of the following methods: a. Prequalified Setion Method as per Appendix 2. b. Shear Bond Method as per Appendix 3.. "Ultimate Strength Method" as per Appendix 4. d. Full sale performane testing as per SDI-T-CD. e. Other methods approved by the authority having jurisdition. 3. Resistane to limit states other than flexure shall be determined in aordane with the other provisions of Setion 2.4B. 4. Dek shall be evaluated for strength under the load ombinations required by the appliable building ode. In the absene of a building ode, the load ombinations presribed by ASCE 7 shall be used. 5. Load Determination: The superimposed load apaity shall be determined by deduting the weight of the slab and the dek from the total load apaity. Unless omposite dek-slabs are designed for ontinuity, slabs shall be assumed to at on simple spans. Commentary: Most published live load tables are based on simple span analysis of the omposite system; that is, a ontinuous slab is assumed to rak over eah support and to arry load as a series of simple spans. Commentary: By using the referene analysis tehniques or test results, the dek manufaturer determines the live loads that an be applied to the omposite dek-slab ombination. The results are usually published as uniform load tables. For most appliations, the dek thikness and profile is seleted so that shoring is not required; the live load apaity of the omposite system is usually more than adequate for the superimposed live loads. In alulating the setion properties of the dek, AISI S100 may require that ompression zones in the dek be redued to an effetive width, but as tensile reinforement, the total area of the ross setion may be used. (See Appendix 5) Coatings other than those tested may be investigated, and if there is evidene that their performane is better than that of the tested produt, additional testing may not be required. 6. Conrete: Speified onrete ompressive strength (f ) shall omply with Setion 2.1 and shall not be less then 3000 psi (21 MPa), nor less than that required for fire resistane ratings or durability. 10

12 AMERICAN NATIONAL STANDARDS / STEEL DECK Commentary: Load tables are generally alulated by using a onrete strength of 3000 psi (21 MPa). Composite slab apaities are not greatly affeted by variations in onrete ompressive strength; but if the strength falls below 3000 psi (21 MPa), it would be advisable to hek shear anhor design for omposite beam ation. a. Minimum Cover: The onrete thikness above the top of the steel dek shall not be less than 2 inhes (50 mm), nor that required by any appliable fire resistane rating requirements. Minimum onrete over for reinforement shall be in aordane with ACI 318 Setion Defletion: Defletion of the omposite slab shall be in aordane with the requirements of the appliable building ode. a. Cross setion properties shall be alulated in aordane with Appendix 5. b. Additional defletions resulting from onrete reep, where appliable, shall be alulated by multiplying the immediate elasti defletion due to the sustained load by the following fators: i. (1.0) for load duration of 3 months ii. (1.2) for load duration of 6 months iii. (1.4) for load duration of 1 year iv. (2.0) for load duration of 5 years. Commentary: Live load defletions are seldom a ontrolling design fator. A superimposed live load defletion of span/360 is typially onsidered to be aeptable. The defletion of the slab/dek ombination an be predited by using the average of the raked and unraked moments of inertia as determined by the transformed setion method of analysis. Refer to Appendix 5 of this Standard or SDI-FDDM. Commentary: Limited information on reep defletions is available. This method is similar to the proedure for reinfored onrete slabs. Beause the steel dek initially arries the weight of the onrete when onstruted without shoring, only the superimposed loads should be onsidered when reep defletions are a onern. When shoring is used, the weight of the onrete should be onsidered in the loads whih ontribute to reep. Commentary: Floor vibration performane is the result of the behavior of entire floor system, inluding the support framing. The designer should hek vibration performane using ommonly aepted methods, whih may inlude AISC Design Guide No Speial Loads: The following loads shall be onsidered in the analysis and alulations for strength and defletion: a. Suspended Loads. b. Conentrated Loads. Moving Loads d. Cyli Loads 11

13 AMERICAN NATIONAL STANDARDS / STEEL DECK 9. One-way Shear Strength: This setion shall be used to determine the one-way shear strength of the omposite dek-slab. LRFD: ' φv4 f A φ V n = φ vv + φ sv D (Eq a) (USCS) 1000 φ Vn = φ vv + φ svd φ v0.332 f ' A (Eq b) (SI) ASD: V n V = Ω Ω v + V D Ω s 4 ' f A Ω 1000 v (Eq ) (USCS) V n ' V VD = + Ω Ωv Ωs Ω (Eq d) (SI) v f A Where: V V = 2λ f A (Eq a) (USCS) ' = 0.166λ f A (Eq b) (SI) ' VD = nominal shear strength of the steel dek setion alulated in aordane with AISI S100, kips (kn) A = onrete area available to resist shear, in 2 (mm 2 ), see Figure 2-1. f' = speified ompressive strength of onrete, psi (MPa) λ = 1.0 where onrete density exeeds 130 lbs/ft 3 (2100 kg/m 3 ); 0.75 where onrete density is equal to or less than 130 lbs/ft 3 (2100 kg/m 3 ). φv = 0.75 φs = 0.85 Ωv = 2.00 Ωs =

14 AMERICAN NATIONAL STANDARDS / STEEL DECK Figure 2-1 One-Way Shear Parameters User Note: The area of the onrete, A defined in Figure 2-1 is relative to the pith width of the steel dek. The vertial shear strength of two webs of the steel dek should be used in ombination with A in Equation 2.4.7a or b. The vertial shear strength is then for the pith with of the dek. This may be onverted to a unit width basis by multiplying by the ratio of the unit width to the pith width of the steel dek. 13

15 AMERICAN NATIONAL STANDARDS / STEEL DECK 10. Punhing Shear Resistane: The ritial surfae for alulating punhing shear shall be perpendiular to the plane of the slab and loated outside of the periphery of the onentrated load or reation area. The punhing shear resistane, Vpr, shall be determined as follows: LRFD V pr = ( β ) φ v 1000 f ' b o h 4φ v f ' b o h 1000 (Eq a)(USCS) V pr ( β ) φ v f ' bo h 0.332φv f 'bo h = (Eq b) (SI) ASD ( β ) f ' b o h 4 f ' b o h Ω v Ω v Vpr = (Eq ) (USCS) V ( β ) f ' b h f ' b h o o pr = (Eq d) (SI) Ω v Ω v Where: bo = perimeter of ritial setion, in. (mm). h = thikness of onrete over above steel dek, in. (mm) Vpr = punhing shear resistane, kips (kn) β = ratio of long side to short side of onentrated load or reation area φv = 0.75 Ωv = 2.00 The ritial setion shall be loated so that the perimeter bo is a minimum but need not be loser than h/2 to the periphery of the onentrated load or reation area. 11. Conentrated Loads: Conentrated loads shall be permitted to be laterally distributed perpendiular to the dek ribs in aordane with this setion. Alternate lateral load distributions based on rational analysis shall be permitted when allowed by the authority having jurisdition. a. Conentrated loads shall be distributed laterally (perpendiular to the ribs of the dek) over an effetive width, be. The load distribution over the effetive width, be, shall be uniform. 14

16 AMERICAN NATIONAL STANDARDS / STEEL DECK b. The onrete above the top of steel dek shall be designed as a reinfored one-way onrete slab in aordane with ACI 318 Chapter 7, transverse to the dek ribs, to resist the weak axis moment, Mwa, over a width of slab equal to W. Appropriate load and resistane fators as required by ACI 318 shall be applied to the weak axis moment. Where: bm = b2 + 2 t + 2 tt (Eq ) be = bm + (2)(1-x/L)x (t/h) for single span bending (Eq ) be = bm + (4/3)(1-x/L)x (t/h) for ontinuous span bending when reinforing steel is provided in the onrete to develop negative bending. (Eq ) be = bm + (1-x/L)x (t/h) for shear (Eq ) W = L/2 + b3 L (Eq ) Mwa = 12 P be / (15W) in-lb per foot (Eq a) (USCS) = P be / (15 W) N-mm per mm (Eq b) (SI) be = Effetive width of onentrated load, perpendiular to the dek ribs, in (mm) bm = Projeted width of onentrated load, perpendiular to the dek ribs, measured at top of steel dek, in (mm) b2 = Width of bearing perpendiular to the dek ribs, in (mm) b3 = Length of bearing parallel to the dek ribs, in (mm) h = Depth of omposite dek-slab, measured from bottom of steel dek to top of onrete slab, in (mm) L = Dek span length, measured from enters of supports, in (mm) Mwa = Weak axis bending moment, perpendiular to dek ribs, of width, in.-lbs per foot of width, (N-mm per mm of width) P = Magnitude of onentrated load, lbs (N) t = Thikness of onrete above top of steel dek, in (mm) tt = Thikness of rigid topping above strutural onrete (if any), in (mm) W = Effetive length of onentrated load, parallel to the dek ribs, in (mm) x = Distane from enter of onentrated load to nearest support, in (mm) 15

17 AMERICAN NATIONAL STANDARDS / STEEL DECK User Note Figure 2-2 User Note Figure

18 AMERICAN NATIONAL STANDARDS / STEEL DECK User Note: User Note Figures 2-2 and 2-3 illustrate the dimensions assoiated with this setion. Commentary: The designer should take into aount the sequene of loading. Suspended loads may inlude eilings, light fixtures, duts or other utilities. The designer should be informed of any loads to be applied after the omposite slab has been installed. Care should be used during the plaement of suspended loads on all types of hanger tabs or other hanging devies for the support of eilings so that an approximate uniform loading is maintained. The individual manufaturer should be onsulted for allowable loading on single hanger tabs. Improper use of hanger tabs or other hanging devies ould result in the overstressing of tabs and/or the overloading of the omposite dek-slab. Commentary: Composite floor dek is not reommended as the only onrete reinforement for use in appliations where the floor is loaded with repeated lift truk (forklift) or similar heavy wheeled traffi. (Lift truks are defined as small power operated vehiles that have devies for lifting and moving produt. The definition of lift truks does not inlude manually operated pallet jaks. ) Loading from lift truks inludes not only moving gravity loads, but also inludes vertial impat loading and in-plane loading effets from starting, stopping, and turning. The repetitive nature of this loading, inluding impat, fatigue, and in-plane effets an be more detrimental to the slab-dek performane than the gravity loads. Suspended floor slabs subjeted to lift truk traffi have speial design requirements to ensure the fatigue stress in the reinforement is low to keep the raks suffiiently tight and servieable to minimize rak spalling due to the hard wheel traffi. The design should only use the steel dek as a stay-in-plae form. Strutural onrete design reommendations ontained in ACI 215R and AASHTO-LRFD are suggested for guidane in the design of these slabs. Due onsideration for the stiffness of the supporting framing should be given by the designer. Composite floor dek has suessfully been used in appliations that are loaded by oasional sissor lift use, and in warehouses with industrial raks without lift truk traffi and in areas servied by pallet jaks. Proper analysis and design for moving and point loads must be performed. Closely spaed onentrated loads an ause overlapping influene zones whih an result in inreased loading within the effetive width of a single load. The effets of there overlapping influene zones must be onsidered. Commentary: Composite floor dek has been used in parking strutures and other similar areas loaded by automobiles; however, the following preautions should be observed: 1. Slabs should be designed as ontinuous spans with negative bending reinforing over the supports; 2. Additional reinforing should be inluded to deter raking aused by large temperature differenes and to provide load distribution; and, 3. In areas where salt water; either brought into the struture by ars in winter or arried by the wind in oastal areas, may deteriorate the dek, protetive measures must be taken. The top surfae of the slab must be effetively sealed so that the salt water annot migrate through the slab to the steel dek. A minimum G90 (Z275) galvanizing is reommended, and, the exposed bottom surfae of the dek should be proteted with a durable paint. The protetive measures must be maintained for the life of the building. 17

19 AMERICAN NATIONAL STANDARDS / STEEL DECK 4. Strong onsideration should be given to using the steel dek as a stay in plae form only, with the onrete slab then being designed to arry all loads as a reinfored onrete slab using reinforing bars. Strutural onrete design reommendations ontained in ACI 215R and AASHTO-LRFD are suggested for guidane in the design of these slabs. Additional information regarding steel floor dek in parking strutures, inluding reommendations for onrete mix design and protetion, may be found in AISC (2003) 12. Negative Reinforement: When the slab is designed for negative moments, the dek shall be designed to at in the negative moment region only as a permanent form. Conrete in negative moment regions shall be designed by the designer as a onventional reinfored onrete slab in aordane with ACI 318. Design moments and shears shall be permitted to be alulated by any aeptable method of analysis whih onsiders ontinuity. The oeffiient method of ACI 318 Setion 6.5 shall be onsidered to be an aeptable analysis method. Commentary: Composite steel dek does not funtion as ompression reinforing steel in areas of negative moment. If the designer desires a ontinuous slab, then negative bending reinforing should be designed using onventional reinfored onrete design tehniques in ompliane with ACI 318. The reinforement hosen for temperature and shrinkage reinforement most likely will not supply suffiient area of reinforement for negative bending over the supports. 13. Cantilevered Slabs: At antilevered slabs, the dek shall be onsidered to at only as a permanent form. The slab shall be designed by the designer for negative bending in aordane with ACI 318. Commentary: At antilevered slabs, the dek ats only as a permanent form. Composite steel dek does not funtion as ompression reinforing steel at antilevers. Negative bending reinforing at the antilever should be designed using onventional reinfored onrete design tehniques in ompliane with ACI 318. The reinforement hosen for temperature and shrinkage reinforing most likely will not supply suffiient area of reinforement for negative bending at the antilever. 14. Diaphragm Shear Capaity: Diaphragm strength and stiffness shall be determined in aordane with AISI S310: User Note: In instanes where the required diaphragm apaity exeeds what an be alulated using AISI S310 a designer an potentially develop additional apaity by designing the diaphragm as a reinfored onrete diaphragm in aordane with ACI 318. This design option as a onrete diaphragm is outside the sope of this Standard. User Note: SDI-DDM ontains diaphragm load tables that omply with AISI S

20 AMERICAN NATIONAL STANDARDS / STEEL DECK 15. Reinforement for Temperature and Shrinkage: a. Reinforement for rak ontrol purposes other than to resist stresses from quantifiable strutural loadings shall be permitted to be provided by one of the following methods: 1. Welded wire reinforement or reinforing bars with a minimum area of times the area of the onrete above the dek (per foot or meter of width), but not be less than the area provided by 6 x 6 W1.4 x W1.4 (152 x 152 MW9 x MW9) welded wire reinforement. 2. Conrete speified in aordane with ASTM C1116, Type I, ontaining steel fibers meeting the riteria of ASTM A820, Type I, Type II, or Type V, at a dosage rate determined by the fiber manufaturer for the appliation, but not less than 25 lb/u yd (14.8 kg/u meter). 3. Conrete speified in aordane with ASTM C1116, Type III, ontaining marosyntheti fibers meeting the riteria of ASTM D7508 at a dosage rate determined by the fiber manufaturer for the appliation, but not less than 4 lb./u yd (2.4 kg/m 3 ). b. When the slab is designed for negative moments in aordane with Setion 2.4.B.12 or Setion 2.4.B.13, temperature and shrinkage reinforement shall be provided in aordane with Setion 2.4.B.15.a. Setion of ACI 318 shall not apply. User Note: It is suggested that if fibers are used for this purpose, that the designer inlude quality ontrol provisions in aordane with ACI 544.3R in the projet speifiations. Commentary: Conrete floor slabs employing Portland ement will start to experiene a redution in volume as soon as they are plaed. Where shrinkage is restrained, raking will our in the floor. The use of the appropriate types and amount of reinforement for shrinkage and temperature movement ontrol is intended to result in a larger number of small raks in lieu of a fewer number of larger raks. Even with the best floor design and proper onstrution, it is unrealisti to expet rak free floors. Every owner should be advised by both the designer and ontrator that it is normal to expet some amount of raking and that suh ourrene does not neessarily reflet adversely on either the adequay of the floor s design or quality of the onstrution. Craking an be redued when the auses are understood and preventative steps are taken in the design phase. The major fators that the designer an ontrol onerning shrinkage and raking inlude ement type, aggregate type and gradation, water ontent, water/ement ratio, and reinforement. Most measures that an be taken to redue onrete shrinkage will also redue the raking tendeny. Drying shrinkage an be redued by using less water in the mixture and the largest pratial maximum-size aggregate. A lower water ontent an be ahieved by using a well-graded aggregate and lower initial temperature of the onrete. Designers are referred to ACI 302.1R and ACI for additional information. 19

21 AMERICAN NATIONAL STANDARDS / STEEL DECK Although raking is inevitable, properly plaed reinforement used in adequate amounts will redue the width of individual raks. By distributing the shrinkage strains, the raks are distributed so that a larger number of narrow raks our instead of a few wide raks. Additional onsideration by the designer may be required to further limit the size and frequeny of raks. Additional provisions for rak ontrol are frequently required where onrete is intended to be exposed, floors that will be subjeted to wheel traffi, and floors whih will reeive an inflexible floor overing material (suh as tile). Modifiations to fiber dosages will vary depending upon the speifi fiber manufaturers reommendations. As a general rule, redued rak widths an be ahieved by inreasing the amount of steel reinforement or by inreasing the fiber dosage and/or minimizing the shrinkage potential of the onrete. Beause omposite dek-slabs are typially designed as a series of simple spans, flexural raks may form over supports. Flexural raking of the onrete in negative moment regions of the slab (over beams and girders) is not typially objetionable unless the floor is to be left exposed or overed with inflexible floor overings. Flexural raking and rak widths an be minimized by one or more of the following: 1.) by paying strit attention to preventing overloads at dek midspan during onstrution, as this is a ommon soure of flexural raks; 2.) utilizing a stiffer steel dek; 3.) reduing the slab span. If flexural raks must be stritly ontrolled, onsideration should be given to designing the omposite dek-slab for negative moments over supports (both beams and girders) and providing appropriate reinforing steel at these supports. 16. Fire Resistane: The designer shall onsider required fire resistane ratings in the design of the omposite slab. Commentary: Fire rating requirements may ditate the onrete strength or density. Many fire rated assemblies that use omposite floor deks are available. In the Underwriters Laboratories Fire Resistane Diretory, the omposite dek onstrutions show hourly ratings for restrained and unrestrained assemblies. ASTM E119 provides information in Appendix X3 titled Guide for Determining Conditions of Restraint for Floor and Roof Assemblies and for Individual Beams, indiating that dek attahed to steel or onrete framing, and interior spans of wall supported dek may be onsidered to be restrained, while end spans of wall supported dek should be onsidered to be unrestrained. Designers should be aware that some fire rated assemblies set limits on load apaity and/or plae restritions on fastener type and spaing. 2.5 Aessories: A. Aessories for strutural appliations shall be of dimensions and thikness suitable for the appliation, and shall be designed in aordane with AISI S100 or AISC 360, as appliable. 20

22 3. Exeution AMERICAN NATIONAL STANDARDS / STEEL DECK 3.1 Installation/General: A. Temporary shoring, if required, shall be designed to resist the loads indiated in Setion 2.4.A.2. The shoring shall be designed and installed in aordane with standards appliable to the speifi shoring system and shall be left in plae until the onrete attains 75% of its speified design strength. User Note: Typial pratie is to retain shoring in plae for a minimum of 7 days. B. Dek Support Attahment: Steel dek shall be anhored to strutural supports by ar spot welds, fillet welds, or mehanial fasteners. The average attahment spaing of dek at supports perpendiular to the span of the dek panel shall not exeed 16 inhes (400 mm) on enter, with the maximum attahment spaing not to exeed 18 inhes (460 mm), unless more frequent fastener spaing is required for diaphragm design. The dek shall be adequately attahed to the struture to prevent the dek from slipping off the supporting struture. User Note: When the sidelap is a standing seam interlok, it may be permissible to only attah the female side, subjet to design requirements, when the female hem holds the male leg down. When the sidelap is a nestable sidelap a single fastener through both sheets of steel dek is aeptable to seure both sheets. C. Dek Sidelap Fastening: For dek with spans less than or equal to 5 feet (1.5 m), sidelap fasteners shall not be required. unless required for diaphragm design. For dek with spans greater than 5 feet (1.5 m), sidelaps shall be fastened at intervals not to exeed 36 inhes (1 m) on enter, unless more frequent fastener spaing is required for diaphragm design, using one of the following methods: 1. Srews with a minimum diameter of inhes (4.83 mm) (#10 diameter) 2. Crimp or button punh 3. Ar spot welds 5/8 inh (16 mm) minimum visible diameter, minimum 1-1/2 inh (38 mm) long fillet weld, or other weld shown to be substantially equivalent through testing in aordane with AISI S905, or by alulation in aordane with AISI S100, or other equivalent method approved by the authority having jurisdition. 4. Other sidelap attahment methods approved by the authority having jurisdition. User Note: The above sidelap spaing is a minimum. Servie loads or diaphragm design may require loser spaing or larger sidelap welds. Good metal-to-metal ontat is neessary for a good sidelap weld. When welding, burn holes are to be expeted and are not a grounds for rejetion. The SDI does not reommend fillet welded or ar spot welded sidelaps for dek that is thinner than inh design thikness (20 gage) due to diffiulty in welding thinner material. D. Dek Perimeter Attahment Along Edges Between Supports: Support at the perimeter of the floor shall be designed and speified by the designer. For dek with spans less than or equal to 5 feet (1.5 m), perimeter attahment shall not be required, unless required for diaphragm design. For dek with spans greater than 5 feet (1.5 m), 21

23 AMERICAN NATIONAL STANDARDS / STEEL DECK perimeter edges of dek panels between span supports shall be fastened to supports at intervals not to exeed 36 inhes (1 m) on enter, unless more frequent fastener spaing is required for diaphragm design, using one of the following methods: 1. Srews with a minimum diameter of inhes (4.83 mm) (#10 diameter) 2. Ar spot welds with a minimum 5/8 inh (16 mm) minimum visible diameter, or minimum 1-1/2 inh (38 mm) long fillet weld. 3. Powder atuated or pneumatially driven fasteners. User Note: This ondition is often referred to as parallel attahment to supports, referring to the support members running parallel or nearly parallel with the flutes of the dek panel. Number 10 srews may not be adequate at thiker edge supports and may frature due to driving torque resistane. A minimum of a Number 12 srew is reommended at parallel edge supports thiker than 14 gage ( inh) and a Number14 srew may be required for thiker and harder steels. E. Cantilevers: 1. Sidelaps shall be attahed at the end of the antilever and at a maximum spaing of 12 inhes (300 mm) on enter from the antilevered end at eah support. 2. Eah dek orrugation shall be fastened at both the perimeter support and the first interior support. 3. The dek shall be ompletely attahed to the supports and at the sidelaps before any load is applied to the antilever. 4. Conrete shall not be plaed on the antilever before onrete is plaed on the adjaent span. F. Minimum fastener edge distanes shall be determined in aordane with AISI S100. G. Dek bearing surfaes shall be brought into ontat as required by the fastening method. Commentary: Out of plane support flanges an reate knife-edge supports and air gaps between the dek and support. This makes welding more diffiult and allows distortion under srew or power atuated fastener washers or heads. Inherent toleranes of the supporting struture should be onsidered. 3.2 Welding A. All welding of dek shall be in aordane with AWS D1.3. Eah welder shall demonstrate the ability to produe satisfatory welds using a proedure in aordane with AWS D1.3. User Note: SDI-MOC desribes a weld quality ontrol test proedure that an be used as a preliminary hek for welding mahine settings under ambient onditions. B. For onnetion of the dek to the supporting struture, weld washers shall be used with ar spot welds on all dek units with metal thikness less than inhes (22 gage) (0.71 mm). Weld washers shall be a minimum thikness of inhes (1.27 mm) and have a nominal 3/8 inh (10 mm) diameter hole. Weld washers shall not be used between supports along the sidelaps. 22

24 AMERICAN NATIONAL STANDARDS / STEEL DECK User Note: AWS D1.3 and AISI S100 do not reommend the use of weld washers for welding sheet steel over inhes (22 gage) in thikness. C. Where weld washers are not required, a minimum visible 5/8 inh (16 mm) diameter ar spot weld or ar seam weld of equal perimeter shall be used. Weld metal shall penetrate all layers of dek material at end laps and shall have good fusion to the supporting members. D. When used, fillet welds to support struture shall be at least 1-1/2 inhes (38 mm) long. E. When steel headed stud anhors are installed to develop omposite ation between the beam or joist and the onrete slab, the steel headed stud anhor shall be permitted as a substitute for an ar spot weld to the supporting struture, subjet to minimum fastener edge distane requirements for ar spot welds in aordane with AISI S100. Steel headed stud anhors shall be installed in aordane with AWS D1.1. F. Dek bearing surfaes to be welded shall be brought into ontat as required by AWS D1.3, Setion Mehanial Fasteners A. When the support fasteners are powder atuated or pneumatially driven, the aeptable range of support thikness, fastener spaing limitations, and the strength per fastener shall be based on the manufaturers appliable fastener test report or other doumentation aeptable to the designer and authority having jurisdition. B. Srews shall be aeptable for use without restrition on strutural support thikness, however, the srew seleted shall have a grip range ompatible with the ombined thikness of the dek and supporting member. User Note: Mehanial fasteners (srews, powder or pneumatially driven fasteners, et.) are reognized as viable anhoring methods, provided the type and spaing of the fastener satisfies the design riteria. Doumentation in the form of test data, design alulations, or design harts should be submitted by the fastener manufaturer as the basis for obtaining approval. Strength of mehanially fastened onnetions are dependant upon both dek and support thikness. 3.4 Aessory Attahment: A. Strutural aessories shall be attahed to supporting struture or dek as required for transfer of fores, but at a spaing not to exeed 12 inhes (300 mm) on enter. Nonstrutural aessories shall be attahed to supporting struture or dek as required for servieability, but spaed not to exeed 24 inhes (600 mm) on enter. B. Mehanial fasteners or welds shall be permitted for aessory attahment. 3.5 Cleaning Prior to Conrete Plaement: A. Surfaes shall be leaned of debris, inluding but not limited to, welding rods, stud ferrules whih are broken free from the stud, and exess fasteners, prior to onrete plaement. 3.6 Reinforing steel shall be installed when required by the onstrution douments. 23