“Computational Civil Engineering - "Intersections" International Journal

“Computational Civil Engineering 2005”, International Symposium 203- The rigid-plastic analysis is using a calculus capable moment of theconnection, but only if the connection can develop a satisfactoryrotation capacity.- The elasto-plastic analysis is based on non-linear modeling of themoment-rotation characteristic of the connection.2. LINEAR ELASTIC ANALYSIS FOR RIGID AND SEMI-RIGIDFRAMES2.1. Basic concept descriptionThe linear analysis is the most widely used method in practice and it has been usedby engineers in designing the majority of structures in human history. The methodhas the advantages of being easy-to-understand, and simplicity in computation. Thesuperposition effects principle can be applied in a linear analysis knowing that theresponse of the structure is equal to the sum of all the effects due to different loadcases.In conventional linear analysis, the deflection of a structure is assumed to be verysmall and the second-order effects due to the geometrical changes can be ignored.The stiffness of the structural members is also considered as constant andindependent of the axial force. The linear assumption for structure behavior ignoresthe P-δ and P-∆ effects due to the element and global structural deflections as wellas any material non-linearity including yielding and the plastic hinges formation.Over the last century, a number of manual and automatically methods for linearanalysis of frame structures has been developed. The most general methodssuitable for computer applications are the stiffness and the flexibility methods.2.2. Computer programThis section describes a FORTRAN- based computer program which can be usedfor the linear analysis of two-dimensional frames.The computer program is divided into two parts, the first one consisting in aFORTRAN program which generates the working data file and the second, whichreads the data file and generates the output files. The schematic diagram shown infigure 1., explains the operation procedure of the computer program.Program CADRE.EXE is developed based on the matrix formulation of thedisplacement method. The program performs first-order elastic analysis of planarframes with or without semi-rigid connections.The input data file contains two categories of data: information of the structuregeometry and external loads.The algorithm of the program is schematic presented in figure 2.