Experimental Study Of Long-span Glulam Beam String Structure Cross Section Optimization

In recent years,with the development of modern wood structure in China,Glulam has become an important part of modern wood structure,and is gradually favored by long-span wooden structure.It can improve the overall quality by controlling the quality of each layered,and it can also prevent wood from cracking.In addition,it can be adhered to the required span and shape according to the engineering needs.However,the strength of wood is relatively low,and in the application of large-span timber structure,it often requires a large cross section,resulting in large amount of wood and high cost.In this paper,the structure of the beam is applied to the large span wood structure roof frame,and the beam string beam of large span is optimized.The main contents of the study are:(1)The static performance of the beam structure was calculated using SAP2000 software.Determined the pull of the lasso by the control of the deflection of the string beam,and the static performance of the structure is analyzed in detail.(2)Designed a similar ratio of 1:3 scale experimental model for the static loading test.Through the analysis and calculation of the test results,The load and deflection of the string beam and the ultimate bearing capacity are tested and verified.(3)In this paper,the optimization design is carried out and the optimization scheme is tested and verified,then analyzed the static performance of the optimized string beam,Then the feasibility of the optimization scheme was verified.Through test and finite element analysis,the main conclusions are:(1)In the original design scheme,the top of the pole was designed incorrectly,The ear plate breaks when the load reaches the design value.The bottom of the pole should be fixed.The overall structure can work well and meet the design requirements after optimizing the ear plate and the bottom of the pole.(2)Poles in the original design and uneven,lasso poles 1 axial force is the largest,at about 6.79 times that of axial force minimum 3 poles 1 lasso axial force which is about 1.1times the other paragraphs,after optimization design the biggest axial force difference was only about 18.2% of the maximum difference before optimization.(3)Wire rope in the original plan elastic modulus is low,can't meet the design requirements,using phi 15.2 strands to replace,replace the deflection of the whole after 34% of the original deflection,can effectively reduce the deflection of the limitation on the bearing capacity.