NUMERICAL COMBINATION FOR NONLINEAR ANALYSIS OF STRUCTURES COUPLED TO LAYERED SOILS

Abstract

THIS PAPER PRESENTS AN ALTERNATIVE COUPLING STRATEGY BETWEEN THE BOUNDARY ELEMENT METHOD (BEM) AND THE FINITE ELEMENT METHOD (FEM) IN ORDER TO CREATE A COMPUTATIONAL CODE FOR THE ANALYSIS OF GEOMETRICAL NONLINEAR 2D FRAMES COUPLED TO LAYERED SOILS. THE SOIL IS MODELED VIA BEM, CONSIDERING MULTIPLE INCLUSIONS AND INTERNAL LOAD LINES, THROUGH AN ALTERNATIVE FORMULATION TO ELIMINATE TRACTION VARIABLES ON SUB-REGIONS INTERFACES. A TOTAL LAGRANGEAN FORMULATION BASED ON POSITIONS IS ADOPTED FOR THE CONSIDERATION OF THE GEOMETRIC NONLINEAR BEHAVIOR OF FRAME STRUCTURES WITH EXACT KINEMATICS. THE NUMERICAL COUPLING IS PERFORMED BY AN ALGEBRAIC STRATEGY THAT EXTRACTS AND CONDENSES THE EQUIVALENT SOIL´S STIFFNESS MATRIX AND CONTACT FORCES TO BE INTRODUCED INTO THE FRAME STRUCTURE´S HESSIAN MATRIX AND INTERNAL FORCE VECTOR, RESPECTIVELY. THE FORMULATION COVERS THE ANALYSIS OF SHALLOW FOUNDATION STRUCTURES AND PILES IN ANY DIRECTION. FURTHERMORE, THE PILES CAN PASS THROUGH DIFFERENT LAYERS. NUMERICAL EXAMPLES ARE SHOWN IN ORDER TO ILLUSTRATE AND CONFIRM THE ACCURACY AND APPLICABILITY OF THE PROPOSED TECHNIQUE.