During different loading processes, the stiffness variation of the joint assembly is non-linear, and the initial stiffness of the same joint combination is greater than the tangent stiffness. It is used to measure the vertical displacement of the beam monitoring point, and the extensometer is arranged on the outer surface of the column flange and the node domain to measure the rotation of the column node domain and the deformation of the column web, and at the same time the upper and lower flanges of the column near the node Resistance strain gauges or strain gauges are attached to the upper and lower flanges of the beam, the upper and lower stiffeners, and the column webs. The strain values ​​are recorded and output by the UCAM-70A static resistance data acquisition instrument. The dial gauge of the horizontal pressure displacement of the tensile pressure sensor and the measuring beam is directly plotted on the UCAM-70A static resistance data acquisition instrument. The ultimate load of the end plate is the same, the ultimate load of the test piece TB-3 without stiffeners on the column web is 93.2kN, which is much smaller than the ultimate load value of the test piece TB-2 with stiffeners, indicating that the stiffener has an effect on the bearing capacity of the joint. Very big. Because the force from the flange of the beam will cause the protruding part of the column flange to be loaded, just like the cantilever beam has bending deformation, the convexity is very serious, indicating that the stiffener has a significant effect on the bearing capacity of the joint. The test pieces TB-1 and TB-2 are equipped with stiffeners at the column joints. The deformation and convexity of the column flanges are obviously delayed during the test. At the same time, the range of the slab plate is limited, the joint stiffness is increased, the ductility is increased, and the force is increased. . The ductility of the joint is very important for the joint bending moment distribution and seismic design. Since most of the energy absorbed by the nodes is consumed by the end plates, the constrained stiffness of the beams to the columns is reduced, and all three members have good ductility and deformation properties. The limit rotation angle of each test piece is greater than the requirement of 0.03 rad for the ductile connection corner in the corresponding FEMA specification. See the detailed values. From the experimental phenomenon analysis, the end plate connected with the web of the beam and column is lifted during the loading process, which is the main reason for the large deformation of the end plate joint. The lifting is characterized by the end plate of the mid-section of the web of the node tension zone and the upper edge of the upper flange being pulled up. The deformation of the column slab is mainly shear deformation. In the elastic phase, the shear deformation is almost negligible. In the elastoplastic stage, the shear deformation of the column slab is rapidly increased, resulting in obvious oblique cracks in the slab. Through the analysis of the test process and the force curve, the pre-tensioning force exerted on the bolt by the semi-rigid connection of the beam and column also affects the force of the joint, and can ensure no slippage between the connected plates; however, the existence of the sliding surface of the bolt in the connection It also provides a better location for releasing energy, which is an advantageous condition for generating greater ductility, which increases the connection stiffness. Conclusion The semi-type of the extended end plate bolt connection is a typical semi-rigid joint connection type with good bearing capacity and ductility. It is very reasonable to apply the semi-rigid connection of the end plate to the multi-layer steel structure frame. The thickness of the end plate in the end plate bolt connection joint, the stiffening rib column flange and web thickness, the column axial force, the bolt diameter and the arrangement are the initial rotational stiffness, ductility, energy dissipation performance, ultimate bearing capacity, and failure form of the joint. The main influencing factors. The shear-slip phenomenon of the end-plate bolted semi-rigid joint under load can not be ignored and should be further studied.
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