1. You are to calculate the forces in a 7 member truss, simply supported at A and C, and subject to a force of 120kN at point B, as shown in the diagram below. Note that the base of the bridge (the members with lengths AB and BC) is horizontal. You are given sufficient details (angles a and k, and lengths AB, AD, BC and DE) for you to calculate the geometry of your bridge Note that k is the angle between the member DE and the horizontal. You must show your working.
When answering this question, please use the 120kN force indicated in the diagram and ignore the mass which is given in the text.
a. Using ONLY the sine and cosine rules, and the fact that you know what the 3 angles of a triangle add up to, find all the lengths and angles in your truss. Produce a list of lengths, and a list of angles, each correct to 4 significant figures. You will need to work to at least 5 significant figures.
b. You are also to calculate the resultant force at each support, and the force in each member (correct to 4 significant figures).
Where a=35°
k = 5°
AB = 10m
BC = 5.9m
AD = 3.2m
DE = 8.2m