Consider the vertical disp of joint B.Assuming that the real loads deform the element an amount dL, the rotation can be found from the virtual –work eqn.This couple moment causes a virtual load u in one of the elements of the body.
A virtual couple moment M’ having a unit magnitude is applied at.By choosing P’ = 1, it can be seen from the solution for follows. on the body and internal virtual work of u.dL on the element As a result, the external virtual force P’ & internal load u “rideĪlong” by and dL & therefore, perform external virtual work of 1.Supports They can strain the material beyond the elastic limit Since no external load acts on the body at A and in the direction of , the disp , can be determined by first placing on the body a “virtual” load such that this force P’ acts in the same direction as We will choose P’ to have a unit magnitude, P’ =1 Once the virtual loadings are applied, then the body is subjected to the real loads P1, P2 and P3, Point A will be displaced an amount causing the element to deform an amount dLĬhapter 9: Deflections Using Energy Method Structural Analysis 7th Edition © 2009 Pearson Education South Asia Pte Ltd It is to be understood that these loads cause no movement of the.Suppose it is necessary to determine the disp of point A on the body caused by the “real loads” P1, P2 and P3 Chapter 9: Deflections Using Energy Method Structural Analysis 7th Edition © 2009 Pearson Education South Asia Pte Ltd. Able to determine unknown reaction forces caused by member loads, support settlement/ displacement, fabrication error or temperature change. Able to establish the compatibility of displacement equation of the indeterminate structures. Able sketch primary and released structures. Able to calculate degree of indeterminacy of the trusses. LEARNING OUTCOMES At the end of the topic, students should be able to: Apply Method of Virtual Work.