Solving the Inverse Problem of Dynamic Load Identification in Two-Dimensional Truss Using Time Weighted Residual Method Shirin Sadat Fatemi Hosseini shirin.fatemi@cv.iut.ac.ir Date of Submission: September 19, 2020 Degree: M.Sc Language: Farsi Department of Civil Engineering Isfahan University of Technology, Isfahan 84156-83111, Iran Identification of dynamic load applied to the structure plays an important role in achieving a safe and economical design of structures. The aim of this study is to identify dynamic load on a two-dimensional truss using Time-Weighted Residual Method which is a meshless method that analyzes the elements by time-weighted satisfaction of the equation of wave propagation through them. The main idea of this method is to use pre-integration terms together with equilibrium equations. Load identification belongs to the category of inverse problems as the other identification problems. Some required data such as initial time and boundary conditions and the shape of domain are unknown and by using alternative information of internal domain the problem would be solved. Supervisors: Dr. Bijan Boroomand (boromand@cc.iut.ac.ir) Dr. Bashir Movahedian (b.movahedian@cc.iut.ac.ir) In this thesis dynamic force variation applied to a truss is estimated by using Least Square Method together with TWRM when the displacement of several internal nodes are known in time domain. Firstly, transformation system matrix is obtained by TWRM, then time history of applied force is determined for the truss by measured response and using Least Square Method. The process of direct method for solving such problem is to satisfy equilibrium equations and initial conditions precisely. Finite Element Method is applied for solving the examples which are solved by TWRM to study and verify the efficiency of the proposed method and indicate merits and weak points of it. Key Words dynamic load identification for a truss, inverse problems, Time-Weighted Residual Method, meshless methods, Finite Element Method