Homework 1
We are going to design the highlighted 2 ft strip (pier) between the garage door opening and the window for out-of-plane loads. Pertinent properties are:
Roof dead load: 540 lb/ft
Roof wind uplift: 340 lb/ft
Roof load eccentricity: 5.31 inches towards inside of wall
Wind pressure: 30 psf
Wind suction: 26 psf
Use f’m = 2000 psi, Grade 60 steel, bars in center of wall, 8 inch CMU, and Type S PCL mortar. Assume that the pier is fully grouted (weight of 75 psf), and the rest of the wall has a weight of 42 psf. Neglect the weight of the door and window.
| Part | Description | Answer |
| A. | Determine the out-of-plane wind load on the pier in terms of kip/ft for the load combination 0.9D+1.0W, wind suction. | |
| B. | For the load combination 0.9D+1.0W, determine Puf, the factored load at the roof level. (kips) | |
| C. | Determine the location of the maximum moment down from the top of the wall for the load combination 0.9D+1.0W, and wind suction. (ft) | |
| D. | Determine the maximum first order moment for the load combination 0.9D+1.0W, and wind suction. (k-ft) | |
| E. | Determine the axial force at the location of the maximum moment for the load combination 0.9D+1.0W, and wind suction. (kip) | |
| F. | Estimate the required area of steel for the load combination 0.9D+1.0W, and wind suction. (in2) | |
| G. | If one bar is used in each of the three cells of the pier, determine the required size of the bar. | |
| H. | Determine the cracked moment of inertia for the load combination 0.9D+1.0W, and wind suction. Use the reinforcement from part G. (in4) | |
| I. | Calculate the moment magnification factor, ψ, for the load combination 0.9D+1.0W, and wind suction. | |
| J. | Calculate the magnified moment, Mufor the load combination 0.9D+1.0W, and wind suction. (kip-ft) | |
| K. | Determine the ratio of the magnified moment to the design moment for the load combination 0.9D+1.0W, and wind suction. | |
| L. | Before checking deflections, we will check the load combination 0.9D+1.0W, but with wind pressure on the wall. Determine the maximum first order moment for the load combination 0.9D+1.0W, and wind pressure. (k-ft) | |
| M. | Determine the axial force at the location of the maximum moment for the load combination 0.9D+1.0W, and wind pressure. (kip) | |
| N. | Calculate the magnified moment, Mufor the load combination 0.9D+1.0W, and wind pressure. (kip-ft) | |
| O. | Determine the ratio of the magnified moment to the design moment for the load combination 0.9D+1.0W, and wind pressure. | |
| P. | We will check deflections for the load combination D+0.6W, with wind pressure. Determine Pf, the load at the roof level. (kips) | |
| Q. | Determine the location of the maximum moment down from the top of the wall for the load combination D+0.6W, and wind pressure. (ft) | |
| R. | Determine the maximum first order moment for the load combination D+0.6W, and wind pressure. (k-ft) | |
| S. | Determine the axial force at the location of the maximum moment for the load combination D+0.6W, and wind pressure. (kip) | |
| T. | Determine the cracking moment of the pier. Use the axial load from 0.9D+1.0W, wind suction, for determining the cracking moment. (k-ft) | |
| U. | Determine the cracked moment of inertia for the load combination D+0.6W, and wind pressure. Use the reinforcement from part G. (in4) | |
| V. | Determine the effective moment of inertia for the load combination D+0.6W, and wind pressure. (in4) | |
| W. | Determine the first-order deflection for the load combination D+0.6W, and wind pressure. (inch) | |
| X. | Determine the deflection magnification factor for the load combination D+0.6W, and wind pressure. | |
| Y. | Determine the magnified deflection for the load combination D+0.6W, and wind pressure. (inch) | |
| Z. | Determine the allowable deflection. (inch) | |
| AA. | Determine the ratio of the magnified deflection to the allowable deflection for the load combination D+0.6W, and wind pressure. |