| The development of modern wooden structures is part of the construction of ecological civilization,and it can also comply with Chinese basic national policy of environmental protection and resource conservation.Chinese research on modern wood structures started late,and many theories and technologies are still in the exploratory stage.The mechanical properties of joint connections are directly related to the reliability of modern wooden structure buildings,and bolt connection technology has been the most widely used in modern wooden structure joint connections.At present,the understanding of the joint form of bolt connection is still insufficient,and the beam-column bolt joint is often assumed to be a hinged connection,which is inconsistent with engineering reality.Therefore,it is of great significance to carry out research on the stiffness and mechanical properties of the glulam bolt joint.This paper proposes a glulam double-leg column frame structure.The frame beams are sandwiched between the double-leg columns and the joints are connected by bolts.In order to study the mechanical properties of the joint,the material properties of the glued wood and bolts used in the joint were first tested,and then the 12 joint specimens were subjected to unidirectional loading and low-cycle repeated loading tests,of which 8 unidirectional loading specimens 4 specimens were repeatedly loaded in low cycle.The bending moment-corner curve,stiffness degradation curve and joints energy dissipation curve of the glulam double-leg column frame joint are obtained.The bolt hole diameter,the number of bolts and the failure form and bearing capacity of the beam end of the steel plate reinforcement are compared and analyzed.The research results show that as the bolt diameter increases,the joints changes from ductile failure to brittle failure,the bearing capacity increases,the stiffness increases,and the energy dissipation capacity decreases.According to the Johansen yield theory,the six common yield modes of beam-column bolted joints are analyzed by plastic theory.The superposition method is used to analyze the double-limbed column joints,the single bolt is analyzed according to the mechanical principle,and the diameter offset method is used to calculate the ultimate flexural bearing capacity.The results show that the relative error between the experimental value and the theoretical value is basically less than 5%.Based on the mechanical analysis,the calculation formulas for the anti-side displacement stiffness and deformation of the bolted joints of the glulam double-limbed column frame structure are deduced.The finite element software ABAQUS was used to numerically simulate the joints of the glulam double-leg column frame,and the bending moment-angle curves under unidirectional loading and low-cycle repeated loading were studied,and the experimental results were compared and analyzed.The results showed that the finite element.The deviation between the simulation result and the test result is within the acceptable range,and the reasons for the error are analyzed.On the basis of verifying the correctness of the finite element model,the influence of parameters such as bolt end distance,bolt strength and bolt arrangement on the ultimate flexural bearing capacity of joint is studied.The research results show that keeping the total distance from the centroid of the bolt group constant,the ultimate flexural bearing capacity of joint arranged in two rows is higher than that of joint arranged in three rows;therefore,under the premise of meeting the requirements of the specification,reduce the bolt separation and glue.The edge distance of the wood can increase the flexural bearing capacity of the joints;when the bolt diameter remains the same,increasing the bolt strength has little effect on the flexural bearing capacity of the joint;when the bolt strength remains the same,increasing the bolt diameter to resist the joints.The effect of improving the bending load capacity is weakened. |
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