THE EXPERIMENTAL STUDY ON MECHANICAL PROPERTIES OF STEEL CRANE-GIRDER BEFORE AND AFTER REINFORCEMENT

摘要

This article focuses on a cracking steel crane girder of one factory,on the basis of extensive investigation and research on the fatigue damage of cracking steel crane girder at home and abroad,in order to improve the effective area and stiffness of the upper area of the crane girder,a reinforcement program is put forward.Through by 2 million times fatigue test of the crane girder before and after reinforcement,this paper researches on the change rules of magnitude and direction about the crack tip principal stress before and after reinforcement.The research shows that the eccentric lateral cracks did not appear principal tensile stress after reinforcement under eccentric concentrated loads,and the compressive stress after reinforcement is significantly less than before reinforcement.It states that the reinforcement angle plays a role in sharing and transferring the load.Sectional stress is redistribution and the stress concentration phenomenon of the crack tip has been alleviated.After reinforcement,the local stiffness of the upper flange and web greatly increases,the upper flange deformation by eccentric load has been reduced,and the deflection of eccentric side upper flange decreases than reinforcement before.Continues to load after dismantle the angle,the deflection of the flange on the eccentric side substantial increases far beyond the standard limits.The results show that it can extend the fatigue remaining service life of fatigue cracking of the steel crane girder by increasing the effective cross section area and stiffness,and it is a good guide on reinforcement and maintenance of actual industrial plant cracking steel crane girder.