7. 2 Element Stiffness Matrix of a Space Truss Local Coordinates 221 7. 3 Transformation of the Element Stiffness Matrix 223 7. 4 Element Axial Force 224 7. 5 Assemblage ofthe System Stiffness Matrix 225 7. 6 Problems 236 8 STATIC CONDENSATION AND SUBSTRUCTURING 8. 1 Introduction 239 8. 2 Static Condensation 239 8. 3 Substructuring 244 8. 4 Problems 259 9 INTRODUCTION TO FINITE ELEMENT MEmOD 9. 1 Introduction 261 9. 2 Plane Elasticity Problems 262 9. 3 Plate Bending 285 9. 4 Rectangular Finite Element for Plate Bending 285 9. 5 Problems 298 APPENDIX I Equivalent Nodal Forces 301 APPENDIXll Displacement Functions for Fixed-End Beams 305 GLOSSARY 309 SELECTED BmLIOGRAPHY 317 INDEX 319 ix Preface This is the first volume of a series of integrated textbooks for the analysis and design of structures. The series is projected to include a first volume in Matrix Structural Analysis to be followed by volumes in Structural Dynamics and Earthquake Engineering as well as other volumes dealing with specialized or advanced topics in the analysis and design of structures. An important objective in the preparation of these volumes is to integrate and unify the presentation using common notation, symbols and general format. Furthermore, all of these volumes will be using the same structural computer program, SAP2000, developed and maintained by Computers and Structures, Inc. , Berkeley, California.