Lightweight Research For The Main Girder Of Bridge Crane

As one of the most important components of the bridge crane,main girder occupies a large proportion of weight of the whole machine.Lightweight research on the structure of the main girder can not only save a lot of manufacturing materials,but also reduce the energy consumption of the overall operation and complete sets of electromechanical control equipments.Against lightweight methods of the box girder at the present time.Most of the researches focus on changing the section size of the main girder,plate thickness,or other parameters.The original structure of the main girder has not been changed too much.In this regard,based on a 32t/14.5m bias-rail main girder,innovative design of the structure was used in this dissertation.Firstly,the mechanical calculation of the main beam under different working conditions were carried out,and then the implementation scheme of lightweight was determined in combination with the stress characteristics of each part.Then,according to the results of finite element analysis of the main beam,the stiffening rib,the end structure and the web was the weakness of the structure.Due to the web structure is the main load bearing part of the main girder,removing the surface material of the web abruptly will cause unpredictable influence on the main girder.Therefore,the stiffening rib and the end structure was designed firstly in this dissertation,and split-and-merge method was mainly adopted in this design.First of all,the Leaf veins stiffener of the main girder was carried out by the method of bionic design,And then the weak part of the end structure was improved.Altogether,eight kinds of schemes were obtained by combing each scheme.According to the topology optimization of the optimal structure,the removable material area on the web is the largest among all parts,and some removable holes were distributed on the web according to certain rules.At the same time,the new stiffening ribs and the end structure also has a certain space for optimization.In order to minimize the weight of the main girder as much as possible,shape and size of the hole was studied in this dissertation.In comparison,rectangular hole was adopted to minimize the weight of the main girder as much as possible.In order to preserve the original processing conditions and reduce the processing cost,the parameters of the transverse rib spacing and the height of the hole was optimized for seeking the best location.The weight of the optimized main girder was reduced by 13.78%compared to the original structure.Finally,according to the results of reliability analysis,modal analysis and transient dynamics analysis.Both strength and stiffness of the main girder was satisfied the safety working conditions.