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Characteristic Test Study on Bearing Capacity of Suction Caisson Foundation Under Vertical Load

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China Ocean Engineering 2020年第2期34卷 267-278页

作者： DAI Guo-liang ZHU Wen-bo ZHAI qian GONG wei-ming ZHAO Xue-liang key laboratory of concrete and prestressed concrete Structure of ministry of education Southeast UniversityNanjing 210096China School of Civil Engineering Southeast UniversityNanjing 210096China

Suction caisson foundations are often subjected to vertical uplift loads,but there are still no wide and spread engineering specifications on design and calculation method for uplift bearing capacity of suction caisson *** it is important to establish an uplift failure *** order to study the uplift bearing mechanism and failure mode of suction caisson foundation,a series of model tests were carried out considering the effects of aspect ratio,soil permeability and loading *** results indicate that the residual negative pressure at the top of caisson is beneficial to enhance uplift bearing *** smaller the permeability coefficient is,the higher the residual negative pressure will *** the residual negative pressure is approximately equal to the water head that causes seepage in the *** the load reaches the ultimate bearing capacity,both the top and bottom negative pressures are smaller than Su and both the top and bottom reverse bearing capacity factors are smaller than 1.0 in soft *** the uplift bearing characteristics of caisson in sandy soil and soft clay,the bearing capacity composition and the calculation method are *** can provide a reference for the engineering design of suction caisson foundation under vertical load.

关键词： suction caisson foundation uplift bearing capacity failure mode negative pressure sandy soil soft clay

A simplified multisupport response spectrum method

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Earthquake Engineering and Engineering Vibration 2012年第2期11卷 243-256页

作者： Ye, Jihong Zhang, Zhiqiang Liu, Xianming key laboratory of concrete and prestressed concrete Structure of ministry of education Southeast University Nanjing 210096 China China Architecture Design and Research Group Beijing 100044 China

A simplified multisupport response spectrum method is *** structural response is a sum of two components of a structure with a first natural period less than 2 *** first component is the pseudostatic response caused by the inconsistent motions of the structural supports,and the second is the structural dynamic response to ground motion *** method is formally consistent with the classical response spectrum method,and the effects of multisupport excitation are considered for any modal response spectrum or modal *** the seismic inputs at each support are the same,the support displacements caused by the pseudostatic response become rigid body *** response spectrum in the case of multisupport excitations then reduces to that for uniform *** other words,this multisupport response spectrum method is a modification and extension of the existing response spectrum method under uniform ***,most of the coherency coefficients in this formulation are simplified by approximating the ground motion excitation as white *** results indicate that this simplification can reduce the calculation time while maintaining ***,the internal forces obtained by the multisupport response spectrum method are compared with those produced by the traditional response spectrum method in two case studies of existing long-span *** the effects of inconsistent support displacements are not considered in the traditional response spectrum method,the values of internal forces near the supports are *** regions are important potential failure points and deserve special attention in the seismic design of reticulated structures.

关键词： multisupport excitation uniform excitation response spectrum method coherency coefficients simplification comparative study

Fatigue Performance of Orthotropic Steel Decks in Super-Wide Steel Box Girder Considering Transverse Distribution of Vehicle Load

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Structural Durability & Health Monitoring 2021年第4期15卷 299-316页

作者： Xudong Wang Changqing Miao Mao Yang Youliang Ding key laboratory of concrete and prestressed concrete structures of ministry of education Southeast UniversityNanjing211189China School of Civil Engineering Southeast UniversityNanjing211189China

This study presents an investigation on the fatigue analysis of four types of details on orthotropic steel decks(OSDs)for a cable-stayed super-wide steel box girder bridge based on finite-element analysis(FEA)with vehicle transverse distribution model(VTDM).A high-fidelity 3D FE model verified by the static load test is established to satisfy the fatigue analysis *** stress behavior of super-wide steel box girders under the vehicle load at different lane locations is ***,considering the effect of VTDM,the fatigue life analysis of four typical details is performed using the Miner cumulative damage *** results show that the vehicle transverse location has a great influence on the stress behavior of details with sharp influence surface,and the stress ranges in the outermost lane are larger than those in other lanes,indicating that the details of OSD in the outermost lane are prone to *** fatigue life analysis indicates that the diaphragm cutout is more prone to fatigue than other details,which should be carefully treated in bridge maintenance.

关键词： Orthotropic steel deck steel box girder fatigue life vehicle transverse distribution model finite element analysis

Experimental study on flexural behavior of ECC/RC composite beams with U-shaped ECO permanent formwork

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Frontiers of Structural and Civil Engineering 2019年第5期13卷 1271-1287页

作者： Zhi QIAO Zuanfeng PAN Weichen XUE Shaoping MENG key laboratory of concrete & prestressed concrete structures of the ministry of education Southeast UniversityNanjing 210096China College of Civil Engineering Tongji UniversityShanghai 200092China School of Civil Engineering Southeast UniversityNanjing 210096China

To enhance the durability of a reinforced concrete structure, engineered cementitious composite (ECC), which exhibits high tensile ductility and good crack control ability, is considered a promising alternative to conventional concrete. However, broad application of ECC is hindered by its high cost. This paper presents a new means to address this issue by introducing a composite beam with a U-shaped ECC permanent formwork and infill concrete. The flexural performance of the ECC/RC composite beam has been investigated experimentally with eight specimens. According to the test results, the failure of a composite beam with a U-shaped ECC formwork is initiated by the crushing of compressive concrete rather than debonding, even if the surface between the ECC and the concrete is smooth as-finished. Under the same reinforcement configurations, ECC/RC composite beams exhibit increases in flexural performance in terms of ductility, load-carrying capacity, and damage tolerance compared with the counterpart ordinary RC beam. Furthermore, a theoretical model based on the strip method is proposed to predict the moment-curvature responses of ECC/RC composite beams, and a simplified method based on the equivalent rectangular stress distribution approach has also evolved. The theoretical results are found to be in good agreement with the test data.

关键词： engineered cementitious composite (ECC) durability ECC/RC composite beam permanent formwork flexural performance theoretical method

Effect of Chloride Content on Bond Behavior Between FRP and concrete

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Transactions of Tianjin University 2010年第6期16卷 405-410页

作者：潘金龙黄毅方邢锋 key laboratory of concrete & prestressed concrete structures of ministry of education of China College of Civil Engineering Southeast University College of Civil Engineering Shenzhen Key Laboratory on Durability of Civil Engineering Shenzhen University

For reinforced concrete structures located along the seaside, the penetration of chloride ions into concrete may be a threat to the durability of the structures. Experimental investigations were carried out to study the effect of chloride content on the bond behavior between concrete and fiber reinforced polymer (FRP) plates. Direct shear tests were conducted on the FRP strengthened concrete members. Before testing, the specimens were immersed in NaCl solutions with concentrations ranging from 3%—15% for di...

关键词： fiber reinforced polymer (FRP) concrete chloride content direct shear test debonding behavior

Prediction method of restoring force based on online AdaBoost regression tree algorithm in hybrid test

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Journal of Southeast University(English Edition) 2020年第2期36卷 181-187页

作者： Wang Yanhua Lü Jing Wu Jing Wang Cheng key laboratory of concrete and Pre-stressed concrete structures of ministry of education Southeast University Nanjing 210096 China

In order to solve the poor generalization ability of the back-propagation(BP)neural network in the model updating hybrid test,a novel method called the AdaBoost regression tree algorithm is introduced into the model updating procedure in hybrid *** the learning phase,the regression tree is selected as a weak regression model to be trained,and then multiple trained weak regression models are integrated into a strong regression ***,the training results are generated through voting by all the selected regression models.A 2-DOF nonlinear structure was numerically simulated by utilizing the online AdaBoost regression tree algorithm and the BP neural network algorithm as a *** results show that the prediction accuracy of the online AdaBoost regression algorithm is 48.3%higher than that of the BP neural network algorithm,which verifies that the online AdaBoost regression tree algorithm has better generalization ability compared to the BP neural network ***,it can effectively eliminate the influence of weight initialization and improve the prediction accuracy of the restoring force in hybrid tests.

关键词： hybrid test restoring force prediction generalization ability AdaBoost regression tree

A simplified simulation method of friction pendulum bearings

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Journal of Southeast University(English Edition) 2018年第4期34卷 480-487页

作者： Wang Yanhua Feng Yan Wu Jing key laboratory of concrete and Pre-Stressed concrete structures of ministry of education Southeast UniversityNanjing 210096China

In order to improve the computation efficiency and simulation accuracy,a novel simplified simulation method for friction pendulum bearing( FPB) is proposed. The behavior of FPB was analyzed based on the stress characteristics of the slider of FPB. Then,a novel simplified FPB model with a single pendulum and a nonlinear spring was established. The mechanical behavior of the simplified model was analyzed and it conformed well to the basic requirements of FPB. Furthermore,shaking table tests of a concrete slab block structure isolated by four FPBs were carried out, followed by finite element simulations of the test using the proposed simplified *** waves and eleven loading scenarios were selected in the test. The results show that the overall trend of the relative displacement time-history curves,the horizontal acceleration time-history curves and the vertical acceleration time-history curves from the numerical simulation match in a good manner with those obtained from the tests. Specifically,it is found that the difference of the peak value within these curves between the simulation and test results is less than 15%,which means that the proposed simplified model can be used to simulate the FPB behaviors under dynamic loadings with acceptable accuracy for engineering purposes.

关键词： friction pendulum bearing (FPB) simplified model finite element modelling shaking table test

A new isolation device using shape memory alloy and its application for long-span structures

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Earthquake Engineering and Engineering Vibration 2011年第2期10卷 239-252页

作者： Ding Youliang Chen Xin Li Aiqun Zuo Xiaobao key laboratory of concrete and prestressed concrete Structure of ministry of education Southeast University Nanjing 210096 China Department of Civil Engineering Nanjing University of Science ＆ Technology Nanjing 210094 China

The key points to consider in determining the effectiveness of using structural isolation with shape memory alloys （SMA） are the constitutive model, the SMA isolation device and the analysis method. In this paper, a simplified constitutive model based on the classic theory of plasticity is proposed to simulate the behavior of the superelasticity of the SMA, in which the martensite volume fraction is considered as one of the state variables. Comparisons between simulation results and experimental results are made and indicate that the proposed constitutive model yields stress-strain curves that are in good agreement with the experimental ones. Thus, the proposed model can correctly simulate the yield mechanism and energy dissipation capacity of the SMA. Next, in order to make full use of the superelasticity of SMA, a new SMA isolator composed of pre-tensioned SMA bars is presented. Then, a finite element analytical model is established to simulate the behavior of the SMA isolator according to its configuration and simplified constitutive model. Finally, a simplified design method for long-span structures installed with SMA isolators is proposed, which is further used to investigate the isolation effects of a space grid structure. Results show that the SMA isolator can reduce the seismic responses of the structure effectively, which indicates the effectiveness of the proposed SMA isolation method.

关键词： shape memory alloy super-elasticity constitutive model seismic response structural isolation space gridstructure

A numerical study on fire endurance of wood beams exposed to three-side fire

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第7期13卷 491-505页

作者： Jin ZHANG 1, Qing-feng XU2, Yi-xiang XU3, Bin WANG1, Jing-xiang SHANG1 (1key laboratory of concrete and prestressed concrete structures of the ministry of education, Southeast University, Nanjing 210096, China) (2Shanghai key laboratory of New Technology Research on Engineering Structure, Shanghai Research Institute of Building Sciences, Shanghai 200032, China) (3Department of Civil Engineering, Strathclyde University, Glasgow G12 8QQ, UK) key laboratory of concrete and prestressed concrete structures of the ministry of education Southeast University Nanjing China Shanghai key laboratory of New Technology Research on Engineering Structure Shanghai Research Institute of Building Sciences Shanghai China Department of Civil Engineering Strathclyde University Glasgow UK

To investigate the fire endurance of wood beams exposed to three-side fire, we conducted bearing capacity tests of two wood beams and experiments of five wood beams exposed to three-side fire. The finite element software ANSYS was also used to predict the fire endurance of those beams with the indirect order coupling method. It was found that the fire endurance decreases as the load level increases, and the reduction ratio tends to decrease. In the case of a certain load level, the fire endurance is improved if the section size is increased or covered by the fire protection coating. The central deformation increases as the fire duration increases, and the ratio of increase tends to rise. On another note, an increase in the density of wood leads to a rise in the fire endurance of a given beam. From the finite element method (FEM) calculation results, the fire endurance decreases as the load level increases, and the reduction ratio tends to decrease. When the load level is greater than 0.5, the fire endurance is significantly reduced, and it does not change significantly when the load level changes. Lastly, for a load level magnitude below 0.5, the fire endurance and load level are proportional to one another.

关键词： Three-side fire Fire endurance Load level Fire prevention measures Finite element analysis Density of wood