Structural Specialization

Transcription

1 Structural Specialization Project: Size beams for the given structural layout using loading conditions specified in the International Building Code. Contents Typical Floor Beam Layout... 2 Building Sections... 2 Building Uses... 3 Assumed Loading... 3 Beam used for sample calculation... 4 Sample Calculation... 5 Final Layout... 6 Sap Model Images...7 Sap Analysis Overview... 9 Saps Design... 9 Appendix

2 Typical Floor Beam Layout Building Sections 2

3 Building Uses Assumed Loading Using the load factors governed by IBC2012 Section , and a dead load provided by the instructor the following table illustrates how the loads were applied to the given structure. Office Space Loads Corridor office Storage Manufacturing DL (lb/ft²) LL (lb/ft²) *D D + 1.6L The values in red (in the table above) were found to control, and were used when designing the subsequent sections. 3

4 Beam used for sample calculation The beam highlighted in blue was selected for sample calculations. 4

5 Sample Calculation The following element illustrates the preliminary design process. 1. A moment (torque) diagram is constructed to determine the maximum moment and shear on the section. 2. Given the maximum moment, AISC 2014 Table 3-2 was used to find an efficient section that would carry both the moment and shear for the given beam. Try: W16X31 ΦMn = 203 k > k = M max ΦVn = 131 k > k = V max Ix = 375 Δ > 1 N.G. 3. The deflection limit on the building imposed by IBC2012 limits the deflections of the member to L/240. L/240 = (20 /240)* (12 /1 ) = 1 maximum deflection allowed. Given Ix = 375, the beam fails for serviceability and must be redesigned. 5

6 4. The next step was to find a moment of inertia provided for a given section that would allow the deflection limit to be met but also still overcome the loads. Try: W18X35 ΦMn = 249 k > k = M max ΦVn = 159 k > k = V max Ix = 510 Δ < 1 Good Final Layout Using the process outlined above the beams were selected and placed according to the plan view depicted below. The spreadsheets showing the design of each section, as well as the assumed accompanying loads can be found in the appendix. 6

7 Sap Model Images Using a structural analysis software known as SAP, the same building was analyzed and a comparison will be made. -Sap Moment diagram of beam F This is consistent with the value calculated, which implies a correct analysis of this member has been carried out. 7

8 -Deflected shape of structure -Moment diagrams of entire structure 8

9 Sap Analysis Overview Sap is a computer based analysis software that allows the user to make quick calculations of structures, and to make preliminary design choices for sizing of structural members. In this analysis we assumed that all members remained in the linear elastic range, and that all members consisted of pinned connections at the joints. In this scenario, the fact that all the connections are pinned would have led to a terribly unstable structure, and the findings of this report should not be used in the design of a building of similar characteristics. Saps Design The sap design varied slightly from mine. This is probably due to a more thorough calculation made by the program wherein it checks for lateral torsional buckling, local flange buckling, and local web buckling. 9

10 Appendix: Office Beam # Area Load psf linear load (klf) max moment (k-ft) V max (k) Section Ix Δ limit Δ x x x A x B x C x Corridor Beam # Area Load psf linear load (klf) max moment (k-ft) V max (k) Section Ix Δ limit Δ x D x P x J x Storage Beam # Area Load psf linear load (klf) max moment (k-ft) V max (k) Section Ix Δ limit Δ x x x M x N x O x

11 Manufacturing Beam # Area Load psf linear load (klf) max moment (k-ft) V max (k) Section Ix Δ limit Δ x x x E x F x K x L x Q x Wind Loads Wind Pressure Windward Leeward height tributary A Kz qz Cp Wind P Force (k) Kh qh Cp Wind P (psf) Force (k) Shear M max (k-ft) total -->

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