Lesson 10 Analysis of trusses by force method （10课分析桁架的力法）.pdfVIP

Module 2 Analysis of Statically Indeterminate Structures by the Matrix Force Method Version 2 CE IIT, Kharagpur Lesson 10 The Force Method of Analysis: Trusses Version 2 CE IIT, Kharagpur Instructional Objectives After reading this chapter the student will be able to 1. Calculate degree of statical indeterminacy of a planar truss 2. Analyse the indeterminate planar truss for external loads 3. Analyse the planar truss for temperature loads 4. Analyse the planar truss for camber and lack of fit of a member. 10.1 Introduction The truss is said to be statically indeterminate when the total number of reactions and member axial forces exceed the total number of static equilibrium equations. In the simple planar truss structures, the degree of indeterminacy can be determined from inspection. Whenever, this becomes tedious, one could use the following formula to evaluate the static indeterminacy of static planar truss (see also section 1.3). i m (r j) 2 + − (10.1) where m,j and r are number of members, joints and unknown reaction components respectively. The indeterminacy in the truss may be external, internal or both. A planar truss is said to be externally indeterminate if the number of reactions exceeds the number of static equilibrium equations available 2 (3j − ) (three in the present case) and has exactly members. A t