Study On The Bending Behavior Of Prestressed Glulam Continuous Beams

With the increasing shortage of non-renewable resources,the development of green renewable resources has become an important measure today.Wood,as a natural resource,has the advantages of green environmental protection and renewable energy.It has great development potential in the field of architecture.As the main force component in the building structure,the beam has been fully studied.In the aspect of glulam beams,the predecessors have greatly improved the bearing capacity of the beam by rationally applying prestressing technology and glulam.However,due to its weak ability to transmit bending moments at the joints,the joint stiffness is insufficient.The research level is still limited to simply supported beams.The structural form is limited in terms of the utilization of the material strength and the overall deformation of the beam.Therefore,it is necessary to extend the prestressed simply supported beam to the continuous beam,this paper has carried out the following work:(1)Design the middle connection device required,and verify its rationality through tests,so as to improve the deficiencies.At the middle support,two pieces of glulam wood are connected by steel members.At the top,two spans of steel bars are connected by staggered anchoring arrangement of steel bars.In the middle support,the beam top cover plate and the steel bar are pulled,and the bottom plate of T-shaped parts and the glulam wood bear negative bending moment under compression.Finally,the node stiffness is improved through this reasonable force transmission path.(2)The 18 prestressed continuous beams were divided into two groups according to the different order.The influence of the number of prestressed steel wires and the pre-energizing force on the bending behavior of the beam was studied.By analyzing the limit load,load-deflection curve and load curve of stress-strain relationship,get the following results:When the control pre-tension at constant values to configure the 2 wire group as a benchmark,four configuration,bearing capacity increased by 20.3%?29.4%when configured four prestressed steel wire.And increased by 30.51%?36.36%when the six roots.When the load remains unchanged,gradually increase the stiffness of beam and the strain difference between the various layers of glulam plate decreases;When the number of control wire roots remains unchanged,the group without prestressing force is taken as the benchmark.When the prestressing force is 7kN,the bearing capacity increases by 2.39%?10.14%,and when the load is 14kN,the bearing capacity increases by 6.49%?13.26%.The conclusion is as follows:with the increase of the number of steel wire root,the Glued wood material properties is more fully used,.With 4 prestressed steel wire,the bearing capacity and stiffness of the maximum increase.With the increase of the prestressing force,the continuous beam bearing capacity increases and the plywood compression performance is more fully used.(3)The reasonable working condition in the prestressed continuous beam as a condition of prestressed concrete simply supported beam,bending performance experiment was carried out.Using ABAQUS finite element software for simulating normal continuous beam bending test,and the two results compared with prestressed continuous beams,the results as follows:From the beam to the continuous beam,carrying capacity increased by 40%.Compared with ordinary glulam beams,prestressed continuous beam can save 83.27%of timber,save costs by 56.5%.And Prestressed simply supported beams save 80.2%of wood and save costs by 47.9%.Compared with ordinary continuous beam,the carrying capacity of prestressed glulam continuous beamis 8 times higher and its deformation capacity is 1.3 times higher.The conclusion is that the bending behavior of the continuous beam is improved obviously by the change of the structure form from simply supported to continuous and the action of prestress.