Research On Mechanical Properties Of Cold-formed Thin-wall Steel-Glulam Composite Beams

The steel-wood composite beam is a new type of building component.CoMPared with the steel-concrete composite beam,it is more environmentally friendly and has better seismic performance.CoMPared with steel beams,it has higher rigidity and strength.Simultaneously,the effective combination of wood and steel can give full play to the mechanical properties of the two materials,making the overall performance of the composite beam outstanding.This paper takes a new type of fabricated cold-formed thin-walled steel-glulam composite beam as the research object and uses the means of experiment and finite element simulation to study its mechanical properties.The work is mainly carried out from the following aspects:(1)Four cold-formed thin-walled steel-glulam composite beams were subjected to mechanical tests to observe the composite beams’ failure process and failure modes under various loads.Simultaneously,the deflection trend and the strain changes of steel and wood are analyzed,and the failure mechanism of composite beams is studied.The results show that the two materials can work together and deform together during the composite beam’s stress process and can each exert the excellent characteristics of the material.Simultaneously,the addition of plywood can effectively improve the flexural rigidity and lateral rigidity of the steel beam.Improve the stability of steel beams.(2)The mechanical model of cold-formed thin-walled steel-glulam composite beams was established using ABAQUS finite element software,and the initial steel defects and interface slip effects were considered in the model.Using this model to analyze the bending performance of composite beams,the results show that the simulation calculation method exited in this paper can accurately simulate the force state of actual composite beams,and the final composite beam numerical simulation results are in good agreement with the test results.In order to study the influence of more factors on the flexural performance of composite beams,the effects of steel strength,steel frame form,cold-formed thin-walled steel edge length,plywood reinforcement method and other parameters on the flexural rigidity and bearing capacity of composite beams were studied.Finally,a simplified calculation formula for flexural bearing capacity is proposed.(3)Based on the constitutive relationship of glulam along grain shear(Hashin failure criterion),the corresponding user subroutine UMAT of glulam is compiled in Fortran language,and the secondary development function of ABAQUS is used to simulate the shear of existing glulam beams.The results show that this calculation method can accurately simulate the along-grain shear failure mode of glulam beams,and it is consistent with the final test results.Based on this,a numerical simulation of the shear resistance of the cold-formed thin-walled steel-glulam composite beam model was carried out to demonstrate the procedure’s correctness further.The influence of factors such as shear span ratio,steel plate thickness,loading method on the shear performance of composite beams is analyzed,and the shear mechanism of composite beams is obtained,which lays a theoretical foundation for the subsequent analysis of the shear performance of composite beams.