Experimental Study On Shear Performance Of Bamboo-timber Bonded Beam

The development of green building materials is the inevitable trend of the development of the construction industry.Compared with traditional structural materials,bamboo and timber are low-carbon and renewable materials,which have the advantages of renewable,easy degradation,high strength to weight ratio,and high construction efficiency.Timber has excellent bending and compression resistance and has a long history of architecture in China.Bamboo has the advantages of high tensile strength,strong shear property,high strength to weight ratio,good stability and wear resistance.As we know,China is short of timber resources,also China is the largest bamboo producing area in the world.The species,area,stock and yield of bamboo all rank first in the world.And bamboo is currently recognized as the only green material to replace timber resources.Bamboo-timber bonding components can not only alleviate the shortage of timber resources,but also improve the timber’s problems of poor shear performance and low tensile strength,giving full play to the excellent properties of the two materials to complement each other.When bamboo and timber can be glued together reliably,meantime the glued members can work together as a whole,It can compensate for the performance shortcomings of both and give full play to the performance advantages of both.Compared with single bamboo or timber,its mechanical properties have obvious advantages,which has a broad application prospect in modern architectural structures.In order to provide a reference for the design and application of bamboo-timber gluing beams in China,we did the experimental study on the shear properties of bamboo-timber gluing beams.The study is finished as follows:(1)we completed the mechanical properties tests of side-pressed bamboo aggregate and larch.(2)we finished the shear tests of 14 bamboo and timber bonded beams in five groups,and studied the influences of shear span ratio and the forming method on the failure process,failure mechanism,deformation and shear capacity of bamboo and timber bonded beams.The test results shows that the shear capacity and deformation capacity of bamboo and timber bonded beams are related to the forming mode of the specimens.With the increase of the number of laminated bamboo layers,the shear capacity of laminated bamboo has been improved to a certain extent.The shear bearing capacity of bamboo and timber bonded beams decreases with the increase of shear span ratio(λ≤3).With the increase of the shear span ratio,the beam gets a greater probability of bending shear effect,so that it can exert bending resistance and can improve its deformation capacity to a certain extent.(3)due to uncontrollable factors such as fabrication process and section specificity,there is a high probability that the bamboo/timber bonding specimens will suffer from lamination failure and horizontal joint failure caused by stress concentration.Excluding uncontrollable factors,the load-mid-span displacement curves of all specimens show a linear relationship in the elastic stage,and there is an obvious sign before the failure of the specimens,which is ductile failure.It has outstanding overall performance and good shear resistance,and can give full play to the mechanical properties of both materials.So the improvement of the mechanical properties of the entire specimen depends largely on whether the timber in the compression zone has reached the compressive strength limit.When the timber in the compression zone can give full play to its compressive performance,the specimen can continue to be loaded into the elastoplastic stage,and the high tensile strength of the bamboo in the tension zone determines the upper limit of the specimen’s deformation capacity.(4)we used the ABAQUS finite element analysis software simulate the static load test of 5 specimens,and analyzed the stress distribution,load-deflection relation and strain condition.The results showed that the load-deflection curve was in good agreement with the curve obtained from the test.(5)basing on the premise of the member conforming to the assumption of one flat cross section and the stress-strain constitutive model of both materials,we deduced the tension zone of the bamboo glulam beam line damage occurs bamboo section height ratio of the optimal value and established the calculation formula of shear bearing capacity to provide theoretical basis for the engineering application.