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University of California Berkeley Spring Semester 2024 Civil Environmental Engineering Instructor Alan Kren CEE 247 Homework 3 Assigned February 15 2024 Due February 29 2024 Composite Beam Design A floor framing system has beams that fit withing a 30 x30 grid Beams are spaced at 10 0 centers and span 30 0 to supporting girders The floor system is composed of 3 of normal weight concrete fill over 18 gage W2 deck Concrete compressive strength f c is 3KSI Superimposed dead loads are estimated as follows Flooring ceiling lights 4 PSF 7 PSF MEP HVAC 1 PSF Sprinklers Misc 3 PSF We can estimate beam self weight at 5 PSF this equates to something around 50PLF a good starting point for estimating beam weight This may be a touch conservative but it s fine to use a lighter section than a heavier one if need be Portions of the Vulcraft catalogue for W2 deck can be found at the end of this homework Table 1 Capacity values are for factored dead and live load You can use the table for selecting the deck for strength It s unclear how to use the deflection load as the ratio of factored dead plus factored live loads is not provided Assuming only wet dead load is used then we would use 1 2 x concrete deck beam weight with beam weight the pounds per linear foot of beam distance between beams Table 2 The amount of concrete fill there is over the deck given a specified total thickness This amount is provided in cubic yards per 100 square feet a truly bizarre unit and can be converted to PSF by the equation PSF provided value x 27 cubic feet cubic yard x 145 pounds per cubic foot 100 square feet For this equation normal weight concrete weights 145 pounds per cubic foot Table 3 W2 properties including weight PSF You only need the weight portion of this table The beam supports office live load partition load also a live load and of course must support construction live load Design the beam as a composite beam Assume one diameter stud per down flute thus studs are at 12 on center The studs extend 2 5 above the deck top flute Concrete is normal weight f c 3000PSI You need to complete the following to accomplish your design 1 Create a load table that categorizes dead loads into a Construction dead loads i e i weight of concrete fill and steel deck ii 10 increase in the weight of concrete fill to account for wet dead load deflection iii beam self weight b Superimposed dead load c Office live load partition live load d Construction live load 2 Design to meet a wet dead load deflection limit of 1 Wet dead load are all construction dead loads construction live load 3 Design to meet construction load strength requirements Loads include wet dead loads plus 4 Design to meet composite design strength requirements 5 Design to meet composite design live load deflection limit of or l 360 whichever is less 6 Design to meet a total dead plus live load deflection limit of l 240 7 Include live load reduction as permitted by CBC 1607 11 University of California Berkeley Spring Semester 2024 Civil Environmental Engineering Instructor Alan Kren CEE 247 Homework 3 Assigned February 15 2024 Due February 29 2024 Do not use a member that is less than 16 deep as these tend behave poorly as beams Table 1 Factored Load to W2 Deck for Strength and for Deflection Note It s unclear how to use the deflection load as the ratio of factored dead plus factored live loads is not provided Assuming only wet dead load is used then we would use 1 2 x concrete deck beam weight with beam weight the pounds per linear foot of beam distance between beams University of California Berkeley Spring Semester 2024 Civil Environmental Engineering Instructor Alan Kren CEE 247 Homework 3 Assigned February 15 2024 Due February 29 2024 Table 2 Volume Concrete Yards per 100 Square Foot Based on Total Concrete Thickness Example 5 5 NWC on W2 3 cover Weight per square foot 1 39 yards x 27 cubic foot yard x 145 pounds cubic foot 100 square feet 54 4PSF University of California Berkeley Spring Semester 2024 Civil Environmental Engineering Instructor Alan Kren CEE 247 Homework 3 Assigned February 15 2024 Due February 29 2024 Table 3 W2 Properties

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