Tiêu đề 20 Influence Diagram on Trusses.pdf ✅

PSAD 20: Influence Diagram on Trusses This module discusses the technique in drawing influence diagram on truss members using Muller-Breslau Principle. Any member in a truss system has its individual influence diagram. Its diagram, using Muller- Breslau principle can be determined by identifying which quantity of an equivalent beam member is dealt with (moment, shear, reaction) based on the methods of truss analysis (method of joints and sections). An assumption in influence line on trusses is that a unit load is set to move along the main cord (in the figure shown, the bottom cord) For this module, the truss below will be utilized for discussion purposes. 1. Based on support reaction Shown in the truss, members that are directly related to the support reactions are members AE, AB, FD, and CD. From method of sections, Therefore, to solve for FAE, ∑Fv = 0 Av + FAE sin θ = 0 FAE = − Av sin θ Thus, to show the influence line for FAE, first construct the I.L. for Av which can be solved using Muller-Breslau Principle.
Figure 1 Influence Line for Av Now apply FAE = − Av sin θ , The influence line for FAE is 2. Based on shear From the truss shown, the members that may be based from influence line on shear is member EC. To solve for FEC, use the method of sections. From the two cutting planes shown, it resembles the shear at points B and C but in this truss, it is just the same cutting plane since loads are usually placed at joints. Therefore, to solve for the influence line for FEC, combine the influence lines for shear at B and C.