For sites susceptible to liquefaction induced lateral spreading during a probable earthquake, geotechnical engineers often need to know the undrained residual shear strength of the liquefied soil deposit to estimate l...For sites susceptible to liquefaction induced lateral spreading during a probable earthquake, geotechnical engineers often need to know the undrained residual shear strength of the liquefied soil deposit to estimate lateral spreading displacements, and the forces acting on the piles from the liquefied soils in order to perform post liquefaction stability analyses. The most commonly used methods to estimate the undrained residual shear strength （Su~） of liquefied sand deposits are based on the correlations determined from liquefaction induced flow failures with SPT and CPT data. In this study, 44 lateral spread case histories are analyzed and a new relationship based on only lateral spread case histories is recommended, which estimates the residual shear strength ratio of the liquefiable soil layer from normalized shear wave velocity. The new proposed method is also utilized to estimate the residual lateral displacement of an example bridge problem in an area susceptible to lateral spreading in order to provide insight into how the proposed relationship can be used in geotechnical engineering practice.展开更多
In order to investigate shear carrying capacity of H-steel concrete beam with small shear span ratio,shear test on 5 H-steel concrete composite beams with small span ratio (from 0.7 to 1.1) are reported,including test...In order to investigate shear carrying capacity of H-steel concrete beam with small shear span ratio,shear test on 5 H-steel concrete composite beams with small span ratio (from 0.7 to 1.1) are reported,including test design,test scheme,test method,failure characteristics and test results. Influences of shear span ratio,web of H steel and concrete on shear carrying capacity of this kind of beam are investigated. The main components comprising shear bearing capacity are analyzed. The results show that with the shear span ratio increasing,the contribution of web of H steel and concrete on shear carrying capacity decrease. Based on test data,the calculation formula of shear carrying capacity for this beam is established by curve fitting.展开更多
The dynamic shear modulus for three types of undisturbed soil under different consolidation ratios is presented by using the resonant column test method. Its effects on surface ground motion is illustrated by calculat...The dynamic shear modulus for three types of undisturbed soil under different consolidation ratios is presented by using the resonant column test method. Its effects on surface ground motion is illustrated by calculation. The test results indicate that the power function is a suitable form for describing the relationship between the ratio of the maximum dynamic shear modulus due to anisotropic and isotropic consolidations and the increment of the consolidation ratio. When compared to sand, the increment of the maximum dynamic shear modulus for undisturbed soil due to anisotropic consolidation is much larger. Using a one-dimensional equivalent linearization method, the earthquake influence factor and the characteristic period of the surface acceleration are calculated for two soil layers subjected to several typical earthquake waves. The calculated results show that the difference in nonlinear properties due to different consolidation ratios is generally not very notable, but the degree of its influence on the surface acceleration spectrum is remarkable for the occurrence of strong earthquakes. When compared to isotropic consolidation, the consideration of actual anisotropic consolidation causes the characteristic period to decrease and the earthquake influence factor to increase.展开更多
The dynamic shear modulus ratio and damping ratio of sandy gravel are important parameters for the seismic response analysis of valley geomorphic sites,which have an important impact on the determination of design gro...The dynamic shear modulus ratio and damping ratio of sandy gravel are important parameters for the seismic response analysis of valley geomorphic sites,which have an important impact on the determination of design ground motion parameters. In this paper,the dynamic triaxial test of sandy gravels has been performed based on the project of the Shangluo Seismic Microzonation. Combined with the other results of sandy gravel,the recommended results of slightly dense,medium dense and dense sandy gravel were obtained. By building the typical site model,the influence of the dynamic shear modulus ratio and the damping ratio uncertainty on the seismic response of the site is studied. The results show that the uncertainty of the average of the dynamic shear modulus ratio and the damping ratio ± 1 times the standard deviation has little effect on the peak acceleration of the sandy gravel site,and the rationality of the grouping and statistical results is explained. Under different probability levels,the change in the shear modulus ratio and damping ratio leads to a significant difference in the high frequency response spectrum.The response spectrum of 0. 04-0. 1s ranges from about 20%,but it has little effect on the long period spectrum of more than 1. 0s. The study of dynamic shear modulus ratio and damping ratio of sandy gravel has the ability to improve the reliability of the designing ground motion parameters.展开更多
Nonlinear finite element analysis and parametric studies were carried out to study the influence of axial load ratio on the shear behavior of the through-diaphragm connections of concrete-filled square steel tubular c...Nonlinear finite element analysis and parametric studies were carried out to study the influence of axial load ratio on the shear behavior of the through-diaphragm connections of concrete-filled square steel tubular columns. The analysis reveals that smaller axial load ratio can improve the shear bearing capacity and ductility while larger axial load ratio will decrease the shear behavior of the through-diaphragm connections. The parametric studies indicate that the axial load ratio should be limited to less than 0.4 and its influence should be considered in the analysis and design of such connections.展开更多
The dynamic shear modulus (DSM) is the most basic soil parameter in earthquake or other dynamic loading conditions and can be obtained through testing in the field or in the laboratory. The effect of consolidation rat...The dynamic shear modulus (DSM) is the most basic soil parameter in earthquake or other dynamic loading conditions and can be obtained through testing in the field or in the laboratory. The effect of consolidation ratios on the maximum DSM for two types of sand is investigated by using resonant column tests. And, an increment formula to obtain the maximum DSM for cases of consolidation ratio κc>1 is presented. The results indicate that the maximum DSM rises rapidly when κc is near 1 and then slows down, which means that the power function of the consolidation ratio increment κc-1 can be used to describe the variation of the maximum DSM due to κc>1. The results also indicate that the increase in the maximum DSM due to κc>1 is significantly larger than that predicted by Hardin and Black's formula.展开更多
The velocity ratio of a free shear layer has an important influence on the spatial development of the large scale coherent structures in the layer. In this study, numerical simulations are performed to get an insight ...The velocity ratio of a free shear layer has an important influence on the spatial development of the large scale coherent structures in the layer. In this study, numerical simulations are performed to get an insight into this problem. The obtained numerical results agree quite well with those of a linear inviscid stability theory and the available experimental data.展开更多
文摘For sites susceptible to liquefaction induced lateral spreading during a probable earthquake, geotechnical engineers often need to know the undrained residual shear strength of the liquefied soil deposit to estimate lateral spreading displacements, and the forces acting on the piles from the liquefied soils in order to perform post liquefaction stability analyses. The most commonly used methods to estimate the undrained residual shear strength （Su~） of liquefied sand deposits are based on the correlations determined from liquefaction induced flow failures with SPT and CPT data. In this study, 44 lateral spread case histories are analyzed and a new relationship based on only lateral spread case histories is recommended, which estimates the residual shear strength ratio of the liquefiable soil layer from normalized shear wave velocity. The new proposed method is also utilized to estimate the residual lateral displacement of an example bridge problem in an area susceptible to lateral spreading in order to provide insight into how the proposed relationship can be used in geotechnical engineering practice.
基金Sponsored by the National Key Technologies R&D Program of China during the 11th Five-Year Plan Period (Grant No.2006BAJ03A10)"New Century Excellent Talents in University"Scheme (Grant No.290)+2 种基金the National Natural Science Foundation of China(Grant No.50178026)the Natural Science Foundation of Heilongjiang Province-General Project (Grant No.E200806)the Foundation of Harbin Program (Grant No.2005AFXXJ017)
文摘In order to investigate shear carrying capacity of H-steel concrete beam with small shear span ratio,shear test on 5 H-steel concrete composite beams with small span ratio (from 0.7 to 1.1) are reported,including test design,test scheme,test method,failure characteristics and test results. Influences of shear span ratio,web of H steel and concrete on shear carrying capacity of this kind of beam are investigated. The main components comprising shear bearing capacity are analyzed. The results show that with the shear span ratio increasing,the contribution of web of H steel and concrete on shear carrying capacity decrease. Based on test data,the calculation formula of shear carrying capacity for this beam is established by curve fitting.
基金National Natural Science Foundation of China under Grant No.51108163Natural Science Foundation of Heilongjiang Province under Grant No.E201104
文摘The dynamic shear modulus for three types of undisturbed soil under different consolidation ratios is presented by using the resonant column test method. Its effects on surface ground motion is illustrated by calculation. The test results indicate that the power function is a suitable form for describing the relationship between the ratio of the maximum dynamic shear modulus due to anisotropic and isotropic consolidations and the increment of the consolidation ratio. When compared to sand, the increment of the maximum dynamic shear modulus for undisturbed soil due to anisotropic consolidation is much larger. Using a one-dimensional equivalent linearization method, the earthquake influence factor and the characteristic period of the surface acceleration are calculated for two soil layers subjected to several typical earthquake waves. The calculated results show that the difference in nonlinear properties due to different consolidation ratios is generally not very notable, but the degree of its influence on the surface acceleration spectrum is remarkable for the occurrence of strong earthquakes. When compared to isotropic consolidation, the consideration of actual anisotropic consolidation causes the characteristic period to decrease and the earthquake influence factor to increase.
基金sponsored by the Earthquake Disaster Prevention and ReductionProgram for the 12th “Five-year Plan” of Shaanxi Province(SCZC2012-TP-905/1)
文摘The dynamic shear modulus ratio and damping ratio of sandy gravel are important parameters for the seismic response analysis of valley geomorphic sites,which have an important impact on the determination of design ground motion parameters. In this paper,the dynamic triaxial test of sandy gravels has been performed based on the project of the Shangluo Seismic Microzonation. Combined with the other results of sandy gravel,the recommended results of slightly dense,medium dense and dense sandy gravel were obtained. By building the typical site model,the influence of the dynamic shear modulus ratio and the damping ratio uncertainty on the seismic response of the site is studied. The results show that the uncertainty of the average of the dynamic shear modulus ratio and the damping ratio ± 1 times the standard deviation has little effect on the peak acceleration of the sandy gravel site,and the rationality of the grouping and statistical results is explained. Under different probability levels,the change in the shear modulus ratio and damping ratio leads to a significant difference in the high frequency response spectrum.The response spectrum of 0. 04-0. 1s ranges from about 20%,but it has little effect on the long period spectrum of more than 1. 0s. The study of dynamic shear modulus ratio and damping ratio of sandy gravel has the ability to improve the reliability of the designing ground motion parameters.
基金Supported by the National Natural Science Foundation of China(No.51268054 and No.51468061)the Natural Science Foundation of Tianjin(No.13JCQNJC07300)Foundation of Xinjiang University(No.XY110137)
文摘Nonlinear finite element analysis and parametric studies were carried out to study the influence of axial load ratio on the shear behavior of the through-diaphragm connections of concrete-filled square steel tubular columns. The analysis reveals that smaller axial load ratio can improve the shear bearing capacity and ductility while larger axial load ratio will decrease the shear behavior of the through-diaphragm connections. The parametric studies indicate that the axial load ratio should be limited to less than 0.4 and its influence should be considered in the analysis and design of such connections.
基金The Science and Technology Ministration of China and the Earthquake Science Foundation of China (Grand No. 102033)
文摘The dynamic shear modulus (DSM) is the most basic soil parameter in earthquake or other dynamic loading conditions and can be obtained through testing in the field or in the laboratory. The effect of consolidation ratios on the maximum DSM for two types of sand is investigated by using resonant column tests. And, an increment formula to obtain the maximum DSM for cases of consolidation ratio κc>1 is presented. The results indicate that the maximum DSM rises rapidly when κc is near 1 and then slows down, which means that the power function of the consolidation ratio increment κc-1 can be used to describe the variation of the maximum DSM due to κc>1. The results also indicate that the increase in the maximum DSM due to κc>1 is significantly larger than that predicted by Hardin and Black's formula.
基金Project supported by the National Natural Science Foundation of china
文摘The velocity ratio of a free shear layer has an important influence on the spatial development of the large scale coherent structures in the layer. In this study, numerical simulations are performed to get an insight into this problem. The obtained numerical results agree quite well with those of a linear inviscid stability theory and the available experimental data.
