The behavior of rigid piles in sandy soils under one-way cyclic oblique tensile loading represents a critical design consideration for floating renewable devices.These piles,when moored with catenary or taut moorings,...The behavior of rigid piles in sandy soils under one-way cyclic oblique tensile loading represents a critical design consideration for floating renewable devices.These piles,when moored with catenary or taut moorings,experience one-way cyclic tensile loads at inclinations ranging from 0°(horizontal)to 90°(vertical).However,the combined effects of cyclic loading and load inclination remain inadequately understood.This study presents findings from centrifuge tests conducted on rough rigid piles installed in dense sand samples.The results demonstrate that load inclinations significantly influence both cyclic response and ultimate capacity of the piles.Based on the observed cyclic response characteristics,the vertical cyclic load amplitude should not exceed 25%of the ultimate bearing capacity to maintain pile stability.A power expression(with exponent m values ranging from 0.055 to 0.065)is proposed for predicting cumulative pile displacement under unidirectional cyclic loading at inclinations from 0°to 60°.The cyclic response exhibits reduced sensitivity to horizontal cyclic load magnitude,with m-value increasing from 0.06 to 0.14 as load magnitude increases from 0.3 to 0.9.For piles maintaining stability under oblique cyclic loading,the average normalized secant stiffness exceeds 1 and increases with decreasing inclination,indicating enhanced pile stiffness under cyclic loading.For load inclinations below 30°,pile stiffness can be determined using logarithmic function.展开更多
Thin-walled tubes are increasingly used in automobile industries to improve structural safety.The present work deals with the collapse behavior of double-cell conical tubes subjected to dynamic axial and oblique loads...Thin-walled tubes are increasingly used in automobile industries to improve structural safety.The present work deals with the collapse behavior of double-cell conical tubes subjected to dynamic axial and oblique loads.Crashworthiness of these tubes having different sections(e.g.,circular,square,hexagonal,octagonal,decagonal)was numerically investigated by using an experimentally validated finite element model generated in LS-DYNA.Geometry of these tubes was then optimized by decreasing the cross section dimensions at the distal end while the weight remained unchanged.Octagonal conical tube was finally found to be more preferable to the others as a collision energy absorber.In addition,square and circular tubes showed diamond deformation mode,while the other tubes collapsed in concertina mode.A decision making method called TOPSIS was finally implemented on the numerical results to select the most efficient energy absorber.展开更多
In order to investigate the energy absorption characteristics of multi-cell polygonal tubes with different cross-sectional configurations,firstly,the theoretical formulae of the mean crushing force under axial load fo...In order to investigate the energy absorption characteristics of multi-cell polygonal tubes with different cross-sectional configurations,firstly,the theoretical formulae of the mean crushing force under axial load for four multi-cell polygonal tubes were derived by combining the Super Folding Element theory with Zhang’s research results.These formulae can be used to validate the numerical model and quickly evaluate the energy absorption ability of multi-cell polygonal tubes.Furthermore,a comparative study on the energy absorption performance of eight multi-cell polygonal tubes under axial and oblique loads was conducted.The results show that all tubes have a stable mixed deformation mode under axial load.The multi-cell decagon tube has better energy-absorption ability compared with other tubes.Whenθis less than 10°,all the tubes maintain a stable deformation mode,and the multi-cell decagon tube also has the biggest crushing force efficiency and specific energy absorption among these eight tubes;meanwhile compared with the results atθ=0°,the specific energy absorption of all tubes decreases by about 8%-21%,while the crushing force efficiency increases by 20%-56%.However,at large angles 20°and 30°,all of the tubes collapse in bending modes and lose their effectiveness at energy absorption.展开更多
In this paper,crashworthiness performance of multi-cell conical tubes with new sectional configuration design(i.e.square,hexagonal,octagonal,decagon and circular)has been evaluated under axial and three different obli...In this paper,crashworthiness performance of multi-cell conical tubes with new sectional configuration design(i.e.square,hexagonal,octagonal,decagon and circular)has been evaluated under axial and three different oblique loads.The same weight conical tubes were comparatively studied using an experimentally validated finite element model generated in LS-DYNA.Complex proportional assessment(COPRAS)method was then employed to select the most efficient tube using two conflicting criteria,namely peak collapse force(PCF)and energy absorption(EA).From the COPRAS calculations,the multi-cell conical tube with decagonal cross-section(MCDT)showed the best crashworthiness performance.Furthermore,the effects of possible number of inside ribs on the crashworthiness of the decagonal conical tubes were also evaluated,and the results displayed that the tubes performed better as the number of ribs increased.Finally,parameters(the cone angle,θ,and ratio of the internal tube size to the external one,S)of MCDT were optimized by adopting artificial neural networks(ANN)and genetic algorithm(GA)techniques.Based on the multi-objective optimization results,the optimum dimension parameters were found to beθ=7.9o,S=0.46 andθ=8o,S=0.74 from the minimum distance selection(MDS)and COPRAS methods,respectively.展开更多
To investigate the bilateral shear strength of rectangular frame column subjected to oblique horizontal load, we presented a simplified space truss-arch model developed from unilateral truss-arch model. Main parameter...To investigate the bilateral shear strength of rectangular frame column subjected to oblique horizontal load, we presented a simplified space truss-arch model developed from unilateral truss-arch model. Main parameters in the new model were the cross-sectional area, transverse reinforcement raito, axial load, and material strength of the column. The reduction coefficient of concrete sterength owing to the severe cracking of column was also introduced in the model. Finally, 14 specimens under oblique horizontal load were tested to verified the feasibility and applicability of the space truss-arch model.展开更多
基金supported by Fundamental Research Funds for the Central Universities(Grant No.B200202050)Open Funds of Key Laboratory of Navigation Structure。
文摘The behavior of rigid piles in sandy soils under one-way cyclic oblique tensile loading represents a critical design consideration for floating renewable devices.These piles,when moored with catenary or taut moorings,experience one-way cyclic tensile loads at inclinations ranging from 0°(horizontal)to 90°(vertical).However,the combined effects of cyclic loading and load inclination remain inadequately understood.This study presents findings from centrifuge tests conducted on rough rigid piles installed in dense sand samples.The results demonstrate that load inclinations significantly influence both cyclic response and ultimate capacity of the piles.Based on the observed cyclic response characteristics,the vertical cyclic load amplitude should not exceed 25%of the ultimate bearing capacity to maintain pile stability.A power expression(with exponent m values ranging from 0.055 to 0.065)is proposed for predicting cumulative pile displacement under unidirectional cyclic loading at inclinations from 0°to 60°.The cyclic response exhibits reduced sensitivity to horizontal cyclic load magnitude,with m-value increasing from 0.06 to 0.14 as load magnitude increases from 0.3 to 0.9.For piles maintaining stability under oblique cyclic loading,the average normalized secant stiffness exceeds 1 and increases with decreasing inclination,indicating enhanced pile stiffness under cyclic loading.For load inclinations below 30°,pile stiffness can be determined using logarithmic function.
基金Project(660)supported by University of Mohaghegh Ardabili,Iran
文摘Thin-walled tubes are increasingly used in automobile industries to improve structural safety.The present work deals with the collapse behavior of double-cell conical tubes subjected to dynamic axial and oblique loads.Crashworthiness of these tubes having different sections(e.g.,circular,square,hexagonal,octagonal,decagonal)was numerically investigated by using an experimentally validated finite element model generated in LS-DYNA.Geometry of these tubes was then optimized by decreasing the cross section dimensions at the distal end while the weight remained unchanged.Octagonal conical tube was finally found to be more preferable to the others as a collision energy absorber.In addition,square and circular tubes showed diamond deformation mode,while the other tubes collapsed in concertina mode.A decision making method called TOPSIS was finally implemented on the numerical results to select the most efficient energy absorber.
基金Projects(U1334208,51405516,51275532)supported by the National Natural Science Foundation of ChinaProjects(2015zzts210,2016zzts331)supported by the Fundamental Research Funds for the Central Universities,China
文摘In order to investigate the energy absorption characteristics of multi-cell polygonal tubes with different cross-sectional configurations,firstly,the theoretical formulae of the mean crushing force under axial load for four multi-cell polygonal tubes were derived by combining the Super Folding Element theory with Zhang’s research results.These formulae can be used to validate the numerical model and quickly evaluate the energy absorption ability of multi-cell polygonal tubes.Furthermore,a comparative study on the energy absorption performance of eight multi-cell polygonal tubes under axial and oblique loads was conducted.The results show that all tubes have a stable mixed deformation mode under axial load.The multi-cell decagon tube has better energy-absorption ability compared with other tubes.Whenθis less than 10°,all the tubes maintain a stable deformation mode,and the multi-cell decagon tube also has the biggest crushing force efficiency and specific energy absorption among these eight tubes;meanwhile compared with the results atθ=0°,the specific energy absorption of all tubes decreases by about 8%-21%,while the crushing force efficiency increases by 20%-56%.However,at large angles 20°and 30°,all of the tubes collapse in bending modes and lose their effectiveness at energy absorption.
基金Project(660)supported by University of Mohaghegh Ardabili,Iran
文摘In this paper,crashworthiness performance of multi-cell conical tubes with new sectional configuration design(i.e.square,hexagonal,octagonal,decagon and circular)has been evaluated under axial and three different oblique loads.The same weight conical tubes were comparatively studied using an experimentally validated finite element model generated in LS-DYNA.Complex proportional assessment(COPRAS)method was then employed to select the most efficient tube using two conflicting criteria,namely peak collapse force(PCF)and energy absorption(EA).From the COPRAS calculations,the multi-cell conical tube with decagonal cross-section(MCDT)showed the best crashworthiness performance.Furthermore,the effects of possible number of inside ribs on the crashworthiness of the decagonal conical tubes were also evaluated,and the results displayed that the tubes performed better as the number of ribs increased.Finally,parameters(the cone angle,θ,and ratio of the internal tube size to the external one,S)of MCDT were optimized by adopting artificial neural networks(ANN)and genetic algorithm(GA)techniques.Based on the multi-objective optimization results,the optimum dimension parameters were found to beθ=7.9o,S=0.46 andθ=8o,S=0.74 from the minimum distance selection(MDS)and COPRAS methods,respectively.
基金Funded by Natural Science Foundation of Henan Province Office of Education (No. 2009A560007)Doctor Foundation of Henan Polytechnic University (No. B2008-7)
文摘To investigate the bilateral shear strength of rectangular frame column subjected to oblique horizontal load, we presented a simplified space truss-arch model developed from unilateral truss-arch model. Main parameters in the new model were the cross-sectional area, transverse reinforcement raito, axial load, and material strength of the column. The reduction coefficient of concrete sterength owing to the severe cracking of column was also introduced in the model. Finally, 14 specimens under oblique horizontal load were tested to verified the feasibility and applicability of the space truss-arch model.
