Mechanical Properties And Design Method Of Middle Column Double-deck Shoulder Beam Of Multi-leg-CFST Under Horizontal Load

With the development of industry,heavy duty cranes are widely used in industrial plants.There may be several heavy duty cranes at different elevations in the same span of the plant.The traditional single-deck shoulder beam of CFST column can not meet the needs of industrial production,which puts forward higher requirements for the form and bearing capacity of the shoulder beam.However,there are few researches and relevant specifications on shoulder beam,and the form of it is simple.Therefore,a new type of middle column double-deck shoulder beam of multi-leg-CFST is put forward by our research group.This new type of shoulder beam can be placed with multiple heavy cranes,and has the characteristics of high bearing capacity,clear way of force transmission,space saving and material saving.In this paper,the mechanical properties of the proposed middle column double-deck shoulder beam of multi-leg-CFST under braking load are studied,and the following works are completed:According to the actual project,six specimens of middle column double-deck shoulder beam of multi-leg-CFST are designed and tested.The failure process,phenomenon and strain growth of the specimen were observed.The bearing capacity,strain distribution and failure mode are studied.The results show that the shear failure occurs at the web of the compression side of the lower shoulder beam under the most unfavorable load condition;in the elastic stage of test pieces,the positive strain of the upper and lower shoulder beam web conforms to the plane-section assumption,the shear strain is distributed along the oblique straight line,and the flange of the upper and lower shoulder beam has the phenomenon of stress concentration;the bearing capacity of middle column double-deck shoulder beam of double-leg-CFST is the lowest,and because the lower shoulder beam of middle column double-deck shoulder beam of double-leg-CFST and triple-leg-CFST are double web section,which can be approximately regarded as the superposition of two middle column double-deck shoulder beam of double-leg-CFST,so its bearing capacity is doubled.The bearing capacity of middle column double-deck shoulder beam of triple-leg-CFST decreases faster than the other two in the later stage of loading due to the rapid degradation of the rigidity of the middle column.In general,the ductility of six specimens are very good.ABAQUS is used to carry out the finite element analysis of the test specimens,and the correctness of the finite element analysis is verified by comparing with the test results,and the stress distribution law of each section of the test specimens under each load level is analyzed.The parameter of three kinds of middle column double-deck shoulder beam of multi-leg-CFST are analyzed.The influences of the height ratio of upper shoulder beam section and lower shoulder beam section,the span-depth ratio of the lower shoulder beam,the height ratio of middle column section and lower shoulder beam section on the mechanical performance of the model are revealed.Based on the ductile failure of models,the specific structural requirements are given.Based on the results of test and finite element analysis,three kinds of failure modes of middle column double-deck shoulder beam of multi-leg-CFST are put forward;then,the mechanical model of middle column double-deck shoulder beam of multi-leg-CFST is given,and based on the mechanical model,the calculation formula of bearing capacity of middle column double-deck shoulder beam of multi-leg-CFST under brake load is put forward;finally,The differences between the calculation results of the finite element method and the calculation results are modified,which provides a useful reference for the scientific research and engineering designers.