Department of Civil & Environmental Engineering. CEE 331: Structural Analysis.
Homework #3: Due September 30th. Problem 1: 14-13 in Hibbeler. Also, write ...
University of Massachusetts - Amherst
Department of Civil & Environmental Engineering CEE 331: Structural Analysis Homework #3: Due September 30th Problem 1: 14-13 in Hibbeler. Also, write out the global vectors Du , Dk , Qu , Qk . Problem 2: 14-14 in Hibbeler. Also calculate the reaction forces. Sketch the deflected shape of the truss and show the reaction forces on the sketch. You can use MASTAN to check your results, but must solve the problem by hand. Problem 3: Your task in this problem is to develop a MASTAN model of the ‘Southern Vermont’ truss shown on the Adaptive Bridge Project website http://www.ecs.umass.edu/adaptive bridge use and located in the northwest corner of lot 11 near McGuirk Stadium. You will then compare your results to those obtained in a recent full scale load test of the structure, pictured here.
You should use the drawing located on ‘Adobe page 1’ under bridge dimensions under documentation on the ‘Southern Vermont’ section of the ‘Data’ tab of the project website to obtain dimensions of the truss and the relevant cross sectional areas. You will model only one of the trusses in 2 dimensions. Make the following assumptions: 1. Neglect the selfweight of the truss. 2. The weight of the backhoe is 19,000 lbs. 3. The weight of the backhoe is evenly distributed between the two parallel trusses, and then evenly between two point loads at nodes L1 and L2. 5. The elastic modulus of the truss material is 29,000 ksi. 6. The yield stress of the material is 30 ksi.
1
Develop two models, one with pin boundary conditions at L0 and L3 and one with a pin at L0 and a roller at L3. Based on your visit to the bridge comment on which set of boundary conditions you think is more appropriate. The load test resulted in downward displacement at L1 of approximately 0.15 inches, and at L2 of 0.16 inches. How do your simulation results compare to these. Comment. Use only the attached form to report your results, and attach only the MASTAN printouts requested. Note: Factor of safety is defined here to be the ratio of the axial stress in a member to the yield stress in that member.
2
Report form for problem #3 of HW #3. INPUT: Element
