Moso bamboos have attracted excessive attention as a renewable green building material to the concept of sustainable development.In this paper,the 20 bolted Moso bamboo connection specimens with embedded steel plates ...Moso bamboos have attracted excessive attention as a renewable green building material to the concept of sustainable development.In this paper,the 20 bolted Moso bamboo connection specimens with embedded steel plates and grouting materials were designed according to connection configurations with different bolt diameters and end distance of bolt holes,and their bearing capacities and failure modes were analyzed by static tension tests.According to the test results of all connectors,the failure modes of the specimens are divided into four categories,and the effects of bolt diameter and bolt hole end distance on the connection bearing capacity and failure mode are analyzed.The test results show that the deformation and failure process can be divided into four stages.The main influence factor of connector bearing capacity is bolt diameter.Connectors can be divided into four failure modes,and brittle failure can be avoided by adopting certain structural measures.Filling with grouting material can improve the bearing capacity of joints.Due to the large variability of bamboo,further experiments are needed.展开更多
A new type of beam-to-column connection for steel moment flames, designated as a ＂self-centering connection,＂ is studied. In this connection, bolted top-and-seat angles, and post-tensioned （PT） high-strength steel...A new type of beam-to-column connection for steel moment flames, designated as a ＂self-centering connection,＂ is studied. In this connection, bolted top-and-seat angles, and post-tensioned （PT） high-strength steel strands running along the beam are used. The PT strands tie the beam flanges on the column flange to resist moment and provide self-centering force. After an earthquake, the connections have zero deformation, and can be restored to their original status by simply replacing the angles. Four full-scale connections were tested under cyclic loading. The strength, energy-dissipation capacity, hysteresis curve, as well as angles and PT strands behavior of the connections are investigated. A general FEM analysis program called ABAQUS 6.9 is adopted to model the four test specimens. The numerical and test results match very well. Both the test and analysis results suggest that： （1） the columns and beams remain elastic while the angles sustain plastic deformations for energy dissipation when the rotation of the beam related to the column equals 0.05 tad, （2） the energy dissipation capacity is enhanced when the thickness of the angle is increased, and （3） the number of PT strands has a significant influence on the behavior of the connections, whereas the distance between the strands is not as important to the performance of the connection.展开更多
In this paper,the seismic behaviors of precast bridge columns connected with grouted corrugated-metal duct(GCMD)were investigated through the biaxial quasi-static experiment and numerical simulation.With a geometric s...In this paper,the seismic behaviors of precast bridge columns connected with grouted corrugated-metal duct(GCMD)were investigated through the biaxial quasi-static experiment and numerical simulation.With a geometric scale ratio of 1:5,five specimens were fabricated,including four precast bridge columns connected with GCMD and one cast-in-place(CIP)bridge column.A finite element analysis model was also established by using OpenSees and was then calibrated by using the experimental results for parameter analysis.The results show the biaxial seismic performance of the precast bridge columns connected with GCMD was similar to the CIP bridge columns regarding ultimate bearing capacity and hysteresis energy,and further,that it could meet the design goal of equivalent performance.The seismic performance of the precast bridge columns connected with GCMD deteriorated more significantly under bi-directional load than under uni-directional load.A proper slenderness ratio(e.g.,7.0-10.0)and longitudinal reinforcement ratio could significantly improve the energy dissipation capacity and deformation capacity of the precast bridge columns,while the axial load ratio and concrete strength had little influence on the above properties.The research results could bring insights to the development of the seismic design of precast bridge columns connected with GCMD.展开更多
The construction of grouting butt joints of bamboo tubes is simple and efficient.However,when the joint is bent,the low tensile strength of the mortar easily leads to cracking of the mortar prior to the failure of the...The construction of grouting butt joints of bamboo tubes is simple and efficient.However,when the joint is bent,the low tensile strength of the mortar easily leads to cracking of the mortar prior to the failure of the bamboo tube.In this paper,a comparative test of the bending capacity was performed on grouting butt joints reinforced by nonperforated,fully perforated,and semiperforated steel plates embedded in bamboo tubes to obtain the loaddisplacement curves and ultimate bearing capacity of various specimens.The strengthening effect of CFRP pasted on bamboo tubes was also studied.The results show that the opening at the end of the steel plate is beneficial to resist the slip between the mortar and steel plate,while the complete section in the middle of the steel plate is conducive to making full use of the tensile strength of the steel plate.Therefore,it is best to insert the semiperforated steel plate with openings in the end and without openings in the middle into the mortar to enhance the bending properties of the grouting butt joint,which can make the failure mode of the joint change from brittle failure of mortar to ductile compression failure of bamboo tube.In addition,pasting CFRP sheets on the external wall of the bamboo tube helps to reduce the tensile stress of the mortar,while increasing the width of the steel plate can increase the bending moment of inertia of the mixture of the steel plate and mortar.These two complementary measures are very effective in delaying the cracking of the bamboo tube and improving the bending capacity of the joint.展开更多
The seismic performance of a fully fabricated bridge is a key factor limiting its application.In this study,a fiber element model of a fabricated concrete pier with grouting sleeve-prestressed tendon composite connect...The seismic performance of a fully fabricated bridge is a key factor limiting its application.In this study,a fiber element model of a fabricated concrete pier with grouting sleeve-prestressed tendon composite connections was built and verified.A numerical analysis of three types of continuous girder bridges was conducted with different piers:a cast-in-place reinforced concrete pier,a grouting sleeve-fabricated pier,and a grouting sleeve-prestressed tendon composite fabricated pier.Furthermore,the seismic performance of the composite fabricated pier was investigated.The results show that the OpenSees fiber element model can successfully simulate the hysteresis behavior and failure mode of the grouted sleeve-fabricated pier.Under traditional non-near-fault ground motions,the pier top displacements of the grouting sleeve-fabricated pier and the composite fabricated pier were less than those of the cast-in-place reinforced concrete pier.The composite fabricated pier had a good self-centering capability.In addition,the plastic hinge zones of the grouting sleeve-fabricated pier and the composite fabricated pier shifted to the joint seam and upper edge of the grouting sleeve,respectively.The composite fabricated pier with optimal design parameters has good seismic performance and can be applied in high-intensity seismic areas;however,the influence of pile-soil interaction on its seismic performance should not be ignored.展开更多
基金support from 111 Project(Grant No.B18062)the Graduate Research and Innovation Foundation of Chongqing in China(Grant No.CYS20026)the National Key Research and Development Program of China(Grant No.2017YFC0703504).
文摘Moso bamboos have attracted excessive attention as a renewable green building material to the concept of sustainable development.In this paper,the 20 bolted Moso bamboo connection specimens with embedded steel plates and grouting materials were designed according to connection configurations with different bolt diameters and end distance of bolt holes,and their bearing capacities and failure modes were analyzed by static tension tests.According to the test results of all connectors,the failure modes of the specimens are divided into four categories,and the effects of bolt diameter and bolt hole end distance on the connection bearing capacity and failure mode are analyzed.The test results show that the deformation and failure process can be divided into four stages.The main influence factor of connector bearing capacity is bolt diameter.Connectors can be divided into four failure modes,and brittle failure can be avoided by adopting certain structural measures.Filling with grouting material can improve the bearing capacity of joints.Due to the large variability of bamboo,further experiments are needed.
基金National Natural Science Foundation of China under Nos.50808107,51178250 and 51261120377
文摘A new type of beam-to-column connection for steel moment flames, designated as a ＂self-centering connection,＂ is studied. In this connection, bolted top-and-seat angles, and post-tensioned （PT） high-strength steel strands running along the beam are used. The PT strands tie the beam flanges on the column flange to resist moment and provide self-centering force. After an earthquake, the connections have zero deformation, and can be restored to their original status by simply replacing the angles. Four full-scale connections were tested under cyclic loading. The strength, energy-dissipation capacity, hysteresis curve, as well as angles and PT strands behavior of the connections are investigated. A general FEM analysis program called ABAQUS 6.9 is adopted to model the four test specimens. The numerical and test results match very well. Both the test and analysis results suggest that： （1） the columns and beams remain elastic while the angles sustain plastic deformations for energy dissipation when the rotation of the beam related to the column equals 0.05 tad, （2） the energy dissipation capacity is enhanced when the thickness of the angle is increased, and （3） the number of PT strands has a significant influence on the behavior of the connections, whereas the distance between the strands is not as important to the performance of the connection.
基金National Natural Science Foundation of China under Grant No.51408360the Natural Science Foundation of Fujian(NSFF)under Grant No.2020J01477the Technology Project of Fuzhou Science and Technology Bureau(TPFB)under Grant No.2020-GX-18。
文摘In this paper,the seismic behaviors of precast bridge columns connected with grouted corrugated-metal duct(GCMD)were investigated through the biaxial quasi-static experiment and numerical simulation.With a geometric scale ratio of 1:5,five specimens were fabricated,including four precast bridge columns connected with GCMD and one cast-in-place(CIP)bridge column.A finite element analysis model was also established by using OpenSees and was then calibrated by using the experimental results for parameter analysis.The results show the biaxial seismic performance of the precast bridge columns connected with GCMD was similar to the CIP bridge columns regarding ultimate bearing capacity and hysteresis energy,and further,that it could meet the design goal of equivalent performance.The seismic performance of the precast bridge columns connected with GCMD deteriorated more significantly under bi-directional load than under uni-directional load.A proper slenderness ratio(e.g.,7.0-10.0)and longitudinal reinforcement ratio could significantly improve the energy dissipation capacity and deformation capacity of the precast bridge columns,while the axial load ratio and concrete strength had little influence on the above properties.The research results could bring insights to the development of the seismic design of precast bridge columns connected with GCMD.
基金The authors are grateful for the financial support of the National Key Research and Development Program of China(2017YFC0703500).
文摘The construction of grouting butt joints of bamboo tubes is simple and efficient.However,when the joint is bent,the low tensile strength of the mortar easily leads to cracking of the mortar prior to the failure of the bamboo tube.In this paper,a comparative test of the bending capacity was performed on grouting butt joints reinforced by nonperforated,fully perforated,and semiperforated steel plates embedded in bamboo tubes to obtain the loaddisplacement curves and ultimate bearing capacity of various specimens.The strengthening effect of CFRP pasted on bamboo tubes was also studied.The results show that the opening at the end of the steel plate is beneficial to resist the slip between the mortar and steel plate,while the complete section in the middle of the steel plate is conducive to making full use of the tensile strength of the steel plate.Therefore,it is best to insert the semiperforated steel plate with openings in the end and without openings in the middle into the mortar to enhance the bending properties of the grouting butt joint,which can make the failure mode of the joint change from brittle failure of mortar to ductile compression failure of bamboo tube.In addition,pasting CFRP sheets on the external wall of the bamboo tube helps to reduce the tensile stress of the mortar,while increasing the width of the steel plate can increase the bending moment of inertia of the mixture of the steel plate and mortar.These two complementary measures are very effective in delaying the cracking of the bamboo tube and improving the bending capacity of the joint.
基金This study was supported by the National Natural Science Foundation of China(Grant Nos.52108428,52178446,51978021,and 51908015)the Fundamental Research Funds for the Central Universities(No.2023MS067).We gratefully acknowledge their support.
文摘The seismic performance of a fully fabricated bridge is a key factor limiting its application.In this study,a fiber element model of a fabricated concrete pier with grouting sleeve-prestressed tendon composite connections was built and verified.A numerical analysis of three types of continuous girder bridges was conducted with different piers:a cast-in-place reinforced concrete pier,a grouting sleeve-fabricated pier,and a grouting sleeve-prestressed tendon composite fabricated pier.Furthermore,the seismic performance of the composite fabricated pier was investigated.The results show that the OpenSees fiber element model can successfully simulate the hysteresis behavior and failure mode of the grouted sleeve-fabricated pier.Under traditional non-near-fault ground motions,the pier top displacements of the grouting sleeve-fabricated pier and the composite fabricated pier were less than those of the cast-in-place reinforced concrete pier.The composite fabricated pier had a good self-centering capability.In addition,the plastic hinge zones of the grouting sleeve-fabricated pier and the composite fabricated pier shifted to the joint seam and upper edge of the grouting sleeve,respectively.The composite fabricated pier with optimal design parameters has good seismic performance and can be applied in high-intensity seismic areas;however,the influence of pile-soil interaction on its seismic performance should not be ignored.
