CH11AnalysisofIndeterminateStructuresbytheFlexibilityMethod.ppt

11.6 Support Settlements, Temperature Change, and Fabrication Errors Solution Arbitrarily select the reaction at support B as the redundant. Figure shows the released structure with support C in its displaced position. Since the displacement varies linearly from A, =0.24 in. The forces and displacements produced by a unit value of the redundant are shown 11.6 Support Settlements, Temperature Change, and Fabrication Errors Using the Figure evaluate gives Solution the compatibility equation is The final reactions, computed by statics or by superposition of forces shown in the up figure. 11.6 Support Settlements, Temperature Change, and Fabrication Errors EXAMPLE 11.8 Compute the reaction at support C of the truss if the temperature of bar AB increases , member ED is fabricated 0.3 in too short, support A is constructed 0.48 in to the right of its intended position, and support C is constructed 0.24 in too high. For all bars A=2 in2, E=30,000 kips/in2, and the coefficient of temperature expansion . 11.6 Support Settlements, Temperature Change, and Fabrication Errors Solution We arbitrarily select the reaction at support C as the redundant. Figure 11.17b shows the deflected shape of the released structure to an exaggerated scale. Figure 11.17c shows the forces and deflections produced by a unit value of the redundant. 11.6 Support Settlements, Temperature Change, and Fabrication Errors Solution 11.7 Analysis of Structures with Several Degrees of Indeterminacy The analysis of a structure that is indeterminate to more than one degree follows the same format as that for a structure with a single degree of indeterminacy. The designer establishes a determinate released structure by selecting certain reactions or internal forces as redundants. The unknown redundants are applied to the released structure as loads together with the actual loads The structure is then analyzed separately for each redundant as wel