Study On Synergistic Flexural Performance Of Laminated Steel Beams In Steel Modular Building

The steel structure modular building has the advantages of good mechanical performance,high industrial level and easy quality assurance,and is an important development direction of building industrialization.The connection performance between modules has a decisive influence on the overall behavior of the structure.At present,the commonly used column-column connection has insufficient constraints,the steel beams of the upper and lower modules cannot work together,and the short columns between the layers are not able to fully exert the mechanical properties of the components,causing the construction.The waste of space and steel restricts the development of modular buildings.Therefore,this paper proposes a new type of interbeam connection method to form the composite beam of the upper and lower module beams.The synergistic flexural behavior and its influencing factors,failure modes and cooperative bending mechanism of the laminated steel beams under the plane bending moment are studied.The design of the new type of connection is optimized,and the design formula of the bending capacity of the laminated steel beam considering the synergistic effect is established,which provides a theoretical reference for the application of the laminated steel beam.The in-plane bending test of one independent double beam and three laminated steel beams is completed.The results show that the laminated steel beam has better cohesive bending performance,and its bending capacity and initial bending stiffness are better.The maximum independent double beams increased by 26.67% and 70.65% respectively.In the test,the deformation and failure modes of the bolts were bent or sheared,the joint plate was deformed,the lower beam bolt holes were horizontally pressed outwards along the beam,and the beam was bent and deformed.;the independent double beam upper and lower beams are independently stressed,the upper and lower beam neutral shafts are in the middle of the beam web,the laminated steel beams are co-stressed,and the upper and lower beam neutral axes are close to coincide.The finite element model of the laminated steel beam was established by ABAQUS software.The accuracy was verified by comparison with the test.The factors affecting the cohesive bending performance of the laminated steel beam were analyzed.The analysis shows that with the increase of the number of bolts in the bending section,the combined bending performance of the laminated steel beam is significantly improved,and the flexural bearing capacity and the initial bending stiffness are significantly improved compared with the independent double beams;the bolt diameter,the length of the connecting plate and the thickness of the connecting plate are respectively When the steel beams reach 20 mm,240mm and 8mm,the laminated steel beam can obtain strong synergistic bending performance.The bending capacity and the initial bending stiffness of the specimens are not significantly changed,and the joints are lower than the size;The weld position,bolt position and bolt distance have no obvious influence on the combined bending performance of the laminated steel beam,so the actual project can flexibly arrange the connection.Based on the results of comprehensive tests and numerical simulations,the bending failure modes and the cooperative bending mechanism of the laminated steel beams are analyzed.The failure modes can be divided into two types: joint failure and steel beam yield failure.The synergistic bending mechanism is the horizontal shearing force of the joints,so that the upper and lower beams of the laminated steel beam are changed from the purely bent state to the compression and bending state and the tensioned state.The neutral axis tends to coincide,and the stronger the connection,the more obvious the coincidence trend.The design optimization and analysis of the connection were carried out.The calculation formula of the bending capacity of the laminated steel beam was deduced and verified.The error between the calculated value and the simulated value of the formula was less than 20%,and the reliability was higher.It is found that when the bending bearing capacity is the same,the laminated steel beam under the new connection can save about 15% compared with the independent double-beam steel,saving material and building space.