STUDY OF PERMISSIBLE BEARING PAD BENDING AND DEFORMATION

UNTERSUCHUNG DER ZULAESSIGEN LAGERPLATTENBIEGUNG UND -VERFORMUNG

A TOTAL OF 84 SHORT-TERM CENTRIC AND ECCENTRIC LOADING TESTS WERE CARRIED OUT ON THREE DIFFERENT BEARING PADS CEMENTED BY A JOINT TO A CONCRETE FOUNDATION. THE LOAD WAS APPLIED TO THE BEARING PADS VIA DIFFERENT COMPRESSION PIECES. THE SURFACE STRAIN OF THE BEARING PADS WAS MEASURED IN THREE DIFFERENT DIRECTIONS (RADIALLY, TANGENTIALLY AND BELOW 45 DEGREES) AND THE VERTICAL AND HORIZONTAL STRAINS IN THE CONCRETE WERE ALSO MEASURED. THE STRESSES WERE CALCULATED FROM THE MEASUREMENTS AND THESE WERE USED TO PREPARE DESIGN TABLES FOR CENTRIC LOADING WHICH TAKE ACCOUNT OF THE FOLLOWING PARAMETERS: 1 RELATIVE SLAB THICKNESS, 2 RELATIVE COMPRESSION PIECE DIAMETER, 3 MATERIAL FORMING THE COMPRESSION PIECE, 4 MATERIAL IN THE BEARING PAD, 5 CONCRETE QUALITY, 6 PERMISSIBLE PRESSURE ON THE SURFACE OF THE CONCRETE. THE RESULTS OF THE TESTS ALSO SHOWED THAT THESE DESIGN TABLES CAN BE USED FOR ECCENTRICALLY STRESSED BEARING PADS IF THE PERMISSIBLE LOADS FOR CENTRIC LOADING ARE DECREASED BY THE FACTOR K = (40 X (H/D) - 1) X (E/D) + 1, WHERE (E/D) IS THE ECCENTRICITY RELATED TO THE PRESENT DIAMETER. COMPARISONS WITH THEORETICAL CALCULATIONS AND DESIGNS HAVE SHOWN THAT THE PROPOSED DESIGN METHOD GUARANTEES AN ADEQUATE FACTOR OF SAFETY AND AN OPTIMUM USE OF MATERIAL.