| Prefabricated building is the development trend of the construction industry.By uniformly producing prefabricated components in the factory,transporting them to the construction site and assembling them according to the construction drawings,the overall structure can be quickly formed.Prefabricated buildings have the advantages of fast construction and high industrialization,and reduce building energy consumption and environmental pollution.However,the integrity of prefabricated buildings is poor.Under the action of earthquake,the connection between prefabricated components is often the weak part of the structure.Only by ensuring that the connection has good mechanical properties can prefabricated buildings be safe and reliable.The connection joints of prefabricated concrete structures often use grouting materials to connect prefabricated concrete members into an overall structure.At present,there are few studies on the mechanical properties of the double interface between grouting material and concrete under the combined action of shear and compression.Considering the influence of interface normal stress,63 slant shear specimens with double interface between grouting material and concrete are designed in this paper.Concrete is used as the matrix on both sides of the specimen,and grouting material is used as the bonding material between concrete joints.Taking the interface roughness,keyway structure,joint angle,joint thickness and joint shear reinforcement as the main variables,the specimens were subjected to uniaxial compression loading,and the weak links were analyzed by digital image correlation method.According to the slant shear bond strength of specimens under different influencing factors,the variation law of bond performance was analyzed.The parameters of interface mechanics were obtained by Mohr-Coulomb criterion.Based on the five-zone three-layer interface bond model and shear-friction theory,the shear mechanism of joint interface was analyzed.The results show that :(1)When the aspect ratio of the keyway is large,increasing the interface roughness by increasing the depth of the keyway has no significant effect on the bond strength of the specimen.The three keyway structures have no effect on the failure mode of the spe cimen,and the failure of the key teeth is cut along the root.The joint angle determines the compression-shear ratio of the specimen,and the slant shear bond strength of the specimen is positively correlated with the joint angle.Under the smooth surface(flat joint),the slant shear bond strength decreases with the increase of joint thickness.When the reinforcement ratio of the shear reinforcement(0.283 %)is low,the shear capacity of the specimen does not increase.When the reinforcement ratio is 0.57 %,the shear capacity of the specimen increases,the shear reinforcement does not yield during the whole loading process,and the strength is not fully utilized.(2)The cohesion and internal friction angle of the joint surface are obtained by fitting t he interface stress state.As the roughness increases,the cohesion of the joint surface increases and the internal friction angle decreases.The slant shear bond strength is not only a material property,but also depends on the normal stress,which depends on the inclination angle of the joint.(3)When the thickness of the grouting layer is large,the bonding performance of the specimen depends on the weaker interface between the two interfaces;when the thickness of the grouting layer is small,the failure area of the two interfaces is connected to the final failure surface through the failure section of the grouting layer.The shear composition of the keyway structure joint connection includes the bonding shear resistance in the joint area,the contact friction shear resistance in the joint area and the keyway pin interlocking shear resistance.When there is cross-interface shear reinforcement,it also includes the tensile friction shear resistance of the reinforcement and the shear resistance of the rei nforcement pin. |
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