This paper focuses on the investigation of a hybrid seismic isolation system with passive variable friction dampers for protection of structures against near fault earthquakes. The seismic isolation can be implemented...This paper focuses on the investigation of a hybrid seismic isolation system with passive variable friction dampers for protection of structures against near fault earthquakes. The seismic isolation can be implemented by replacing the conventional columns fixed to the foundations by seismic isolating ones. These columns allow horizontal displacement between the superstructure and the foundations and decouple the building from the damaging earthquake motion. As a result, the forces in the structural elements decrease and damage that may be caused to the building by the earthquake significantly decreases. However, this positive effect is achieved on account of displacements occurring in the isolating columns. These displacements become very large when the structure is subjected to a strong earthquake. In this case, impact may occur between the parts of the isolating column yielding their damage or collapse. In order to limit the displacements in the isolating columns, it is proposed to add variable friction dampers. A method for selecting the dampers＇ properties is proposed. It is carried out using an artificial ground motion record and optimal active control algorithm. Numerical simulation of a sevenstory structure shows that the proposed method allows efficient reduction in structural response and limits the displacements at the seismic isolating columns.展开更多
The method of collaborative work between steel plate anti-wind bearing(AWB) and rubber isolation bearing is proposed to study the vibration reduction effect of isolation structure under stronger wind load,and the func...The method of collaborative work between steel plate anti-wind bearing(AWB) and rubber isolation bearing is proposed to study the vibration reduction effect of isolation structure under stronger wind load,and the function mechanism is explained.Based on a practical project,three kinds of schemes with different isolation layers are put forward,the finite element software ETABS is used for time history analysis,and comparison is made on the seismic response of different isolated structure and aseismic structure.Comparison result shows that the isolation layer with rubber bearing and AWB can work reasonably,but further optimization on the designed parameters is needed.Moreover,the design value of horizontal bearing capacity of lead rubber bearing(LRB) is appropriate to be close to the seismic isolation layer under wind load excitation.Finally,numerical simulation and comparative analysis of shear test of the AWB are conducted.With a very small yield displacement and yield strength over 80% of the set of horizontal bearing capacity,the AWB is validated to satisfy the working conditions which provide the horizontal bearing capacity under normal operating conditions and designed earthquake.The AWB yields and malfunctions,when the maximum displacement is less than the displacement of the isolation layer.展开更多
The low temperature coal tar(CT)is taken as the raw material,and the extraction and column chromatography are used for detailed and accurate characterization in this paper.The n-heptane soluble fraction(CT-HS)and inso...The low temperature coal tar(CT)is taken as the raw material,and the extraction and column chromatography are used for detailed and accurate characterization in this paper.The n-heptane soluble fraction(CT-HS)and insoluble fraction(CT-HI)were obtained by n-heptane Soxhlet extraction.The extraction rate of CT-HS reached 92.79%(mass),which indicated that there are few heavy compounds in it.Further,different solvents(methylbenzene,benzene,ethyl acetate,methylbenzene-ethanol)were used to elute CT-HS by chromatographic column to obtain five fractions(saturates,aromatics,heteroatoms,phenolics and resins,named CT-SA,CT-AR,CT-HE,CT-PH,CT-RE,respectively).The yields of CTSA,CT-AR,CT-HE,CT-PH,CT-RE are 42.12%,10.43%,2.19%,9.50%and 6.63%(mass),respectively.Gas chromatography-mass spectrometry analysis of eluting components show that alkanes are the main components in CT,followed by polycyclic aromatics,and the corresponding fractions are CT-SA and CT-AR,respectively.The relative content of aliphatics in CT-SA is 76.93%,and the relative content of aromatics in CT-AR is 75.05%.This separation technology effectively separates and enriches different components in CT,and the activation energy required for the pyrolysis process of a single eluting fraction is lower than that of CT,which is expected to provide an important reference for the separation,analysis and conversion of complex oil products such as coal-oil co-processing products,coal tar and other complex heavy carbon oil products.展开更多
文摘This paper focuses on the investigation of a hybrid seismic isolation system with passive variable friction dampers for protection of structures against near fault earthquakes. The seismic isolation can be implemented by replacing the conventional columns fixed to the foundations by seismic isolating ones. These columns allow horizontal displacement between the superstructure and the foundations and decouple the building from the damaging earthquake motion. As a result, the forces in the structural elements decrease and damage that may be caused to the building by the earthquake significantly decreases. However, this positive effect is achieved on account of displacements occurring in the isolating columns. These displacements become very large when the structure is subjected to a strong earthquake. In this case, impact may occur between the parts of the isolating column yielding their damage or collapse. In order to limit the displacements in the isolating columns, it is proposed to add variable friction dampers. A method for selecting the dampers＇ properties is proposed. It is carried out using an artificial ground motion record and optimal active control algorithm. Numerical simulation of a sevenstory structure shows that the proposed method allows efficient reduction in structural response and limits the displacements at the seismic isolating columns.
基金the National Natural Science Foundation of China(No.51578160)
文摘The method of collaborative work between steel plate anti-wind bearing(AWB) and rubber isolation bearing is proposed to study the vibration reduction effect of isolation structure under stronger wind load,and the function mechanism is explained.Based on a practical project,three kinds of schemes with different isolation layers are put forward,the finite element software ETABS is used for time history analysis,and comparison is made on the seismic response of different isolated structure and aseismic structure.Comparison result shows that the isolation layer with rubber bearing and AWB can work reasonably,but further optimization on the designed parameters is needed.Moreover,the design value of horizontal bearing capacity of lead rubber bearing(LRB) is appropriate to be close to the seismic isolation layer under wind load excitation.Finally,numerical simulation and comparative analysis of shear test of the AWB are conducted.With a very small yield displacement and yield strength over 80% of the set of horizontal bearing capacity,the AWB is validated to satisfy the working conditions which provide the horizontal bearing capacity under normal operating conditions and designed earthquake.The AWB yields and malfunctions,when the maximum displacement is less than the displacement of the isolation layer.
基金financed by the project supported by the National Natural Science Foundation of China(22078266,21908180,22178289,22278338)the Key Research and Development Program of Shaanxi(2020ZDLGY11-02,2021GY-136)the Special Fund for High-level Scholars of China(XJ21B10)。
文摘The low temperature coal tar(CT)is taken as the raw material,and the extraction and column chromatography are used for detailed and accurate characterization in this paper.The n-heptane soluble fraction(CT-HS)and insoluble fraction(CT-HI)were obtained by n-heptane Soxhlet extraction.The extraction rate of CT-HS reached 92.79%(mass),which indicated that there are few heavy compounds in it.Further,different solvents(methylbenzene,benzene,ethyl acetate,methylbenzene-ethanol)were used to elute CT-HS by chromatographic column to obtain five fractions(saturates,aromatics,heteroatoms,phenolics and resins,named CT-SA,CT-AR,CT-HE,CT-PH,CT-RE,respectively).The yields of CTSA,CT-AR,CT-HE,CT-PH,CT-RE are 42.12%,10.43%,2.19%,9.50%and 6.63%(mass),respectively.Gas chromatography-mass spectrometry analysis of eluting components show that alkanes are the main components in CT,followed by polycyclic aromatics,and the corresponding fractions are CT-SA and CT-AR,respectively.The relative content of aliphatics in CT-SA is 76.93%,and the relative content of aromatics in CT-AR is 75.05%.This separation technology effectively separates and enriches different components in CT,and the activation energy required for the pyrolysis process of a single eluting fraction is lower than that of CT,which is expected to provide an important reference for the separation,analysis and conversion of complex oil products such as coal-oil co-processing products,coal tar and other complex heavy carbon oil products.
