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Seismic performance of an existing bridge with scoured caisson foundation

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Earthquake Engineering and Engineering Vibration 2014年第S1期13卷 151-165页

作者： Kuo-Chun Chang Yu-Chi Sung Kuang-Yen Liu Ping-Hsiung Wang Zheng-Kuan Lee Lu-Sheng Lee Witarto Department of Civil Engineering Taiwan University (NTU) Professor Department of Civil Engineering Taipei University of Technology (NTUT) Center for Research on Earthquake Engineering (NCREE) Associate Researcher Associate Technologist Technologist Department of Civil Engineering The University of Houston Ph.D Student

This paper presents in-situ seismic performance tests of a bridge before its demolition due to accumulated scouring problem. The tests were conducted on three single columns and one caisson-type foundation. The three single columns were 1.8 m in diameter,reinforced by 30-D32 longitudinal reinforcements and laterally hooped by D16 reinforcements with spacing of 20 cm. The column height is 9.54 m,10.59 m and 10.37 m for Column P2,P3,and P4,respectively. Column P2 had no exposed foundation and was subjected to pseudo-dynamic tests with peak ground acceleration of 0.32 g first,followed by one cyclic loading test. Column P3 was the benchmark specimen with exposed length of 1.2 m on its foundation. The exposed length for Column P4 was excavated to 4 m,approximately 1/3 of the foundation length,to study the effect of the scouring problem to the column performance. Both Column P3 and Column P4 were subjected to cyclic loading tests. Based on the test results,due to the large dimension of the caisson foundation and the well graded gravel soil type that provided large lateral resistance,the seismic performance among the three columns had only minor differences. Lateral push tests were also conducted on the caisson foundation at Column P5. The caisson was 12 m long and had circular cross-sections whose diameters were 5 m in the upper portion and 4 m in the lower portion. An analytical model to simulate the test results was developed in the OpenSees platform. The analytical model comprised nonlinear flexural elements as well as nonlinear soil springs. The analytical results closely followed the experimental test results. A parametric study to predict the behavior of the bridge column with different ground motions and different levels of scouring on the foundation are also discussed.

关键词： Analytical models cyclic loads Hydraulic structures Piles Pressure vessels Reinforcement Seismic waves Seismology Soil structure interactions Soils Textile scouring Underwater foundations

cyclic deformation behaviour of natural K_0-consolidated soft clay under different stress paths

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Journal of Central South University 2015年第12期22卷 4828-4836页

作者：孙磊蔡袁强谷川王军郭林 Research Center of Coastal and Urban Geotechnical Engineering Zhejiang University College of Architecture and Civil Engineering Wenzhou University

Characteristic of cyclic loading due to passing wheels is associated with one-way loading without stress reversal,which includes a simultaneous cyclic variation of vertical normal stress and horizontal normal stress lasting for a long period of time and generally takes place in partially-drained conditions.Therefore,it is of great practical relevance to study the deformation behaviour according to the characteristic of traffic loading.In this work,a series of one-way stress-controlled cyclic triaxial tests with a simultaneous variation of the vertical and horizontal stress components during cyclic loading were conducted to investigate the deformation behaviour of natural K_0-consolidated soft clay in partially-drained conditions.Test results demonstrate that not only the deviator part of the stress rules accumulation but also the volumetric part significantly contributes.While the deviator part of the stress amplitude is held constant,the increase amplitude of cyclic confining pressure will promote the development of both permanent volumetric strain and axial strain significantly.Furthermore,the effects of cyclic confining pressure on the deformation of natural K_0-consolidated soft clay was quantified.Finally,an empirical formula for permanent axial strain considering the effects of cyclic confining pressure was proposed which can be used for feasibility studies or for the preliminary design of foundations on K_0-consolidated soft clay subjected to traffic loading.

关键词： cyclic loads triaxial tests natural soft clay soil deformation

Effect of types of reinforcement on plastic hinge rotation parameters of RC beams under pushover and cyclic loading

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Earthquake Engineering and Engineering Vibration 2015年第3期14卷 503-516页

作者： V.V.S.Surya Kumar Dadi Pankaj Agarwal Department of Civil Engineering Institute of Technology Guru Ghasidas Vishwavidyalaya Bilaspur (C.G.) India Assistant Professor Department of Earthquake Engineering Indian Institute of Technology Roorkee

Experimental evaluation of reinforced concrete beam specimens with different characteristics of reinforcement subjected to pushover and cyclic loading is presented.Plastic hinge rotation parameters are determined based on the idealization of pushover and hysteresis curves of reinforced concrete beam specimens constructed in two percentage of reinforcement(0.471%and 0.71%) with different ductile characteristics.The experimental test results provide a clear demarcation of the effect of types of loading and the types of reinforcement on the nonlinear performance characteristics of beam specimens.These results are helpful to update the nonlinear modeling parameters of beam components for the specific type of reinforcement used in the construction of a structure.The updated non-linear modeling parameters of beam components in lumped plasticity model are compared with the values of ASCE/SEI 41-06(2007) used for the performance based design of structures.

关键词： concrete structures pushover loads cyclic loads hy

A review of experimental and theoretical research on the deformation and failure behavior of rocks subjected to cyclic loading

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Journal of Rock Mechanics and Geotechnical Engineering 2021年第5期13卷 1203-1230页

作者： Yi Liu Feng Dai State Key Laboratory of Hydraulics and Mountain River Engineering College of Water Resource and HydropowerSichuan UniversityChengdu610065China

Rock engineering is highly susceptible to cyclic loads resulting from earthquakes,quarrying or rockbursts.Acquiring the fatigue properties and failure mechanism of rocks is pivotal for long-term stability assessment of rock engineering structures.So far,significant progress has been gained on the mechanical characteristics of rocks subjected to cyclic loading.For providing a global insight of typical results and main features of rocks under cyclic loading conditions,this study comprehensively reviews the state-ofthe-art of deformation and failure mechanism and fatigue constitutive relationship of rocks subjected to cyclic loading in the past 60 years.Firstly,cyclic tests on rocks are classified into different types based on loading paths,loading parameters,loading types and environment conditions.Secondly,representative results are summarized and highlighted in terms of the fatigue response of rocks,including the deformation degradation,energy dissipation,damage evolution and failure characteristics;both laboratory testing and numerical results are presented,and various measurement techniques such as X-ray microcomputed tomography(micro-CT)and digital image correlation(DIC)are considered.Thirdly,the influences of cyclic loads on the mechanical characteristics of rocks are discussed,including the cyclic stress,frequency,amplitude and waveform.Subsequently,constitutive relationships for rocks subjected to cyclic loading are outlined,in which typical fatigue constitutive models are compared and analyzed,regarding the elastoplastic model,the internal variable model,the energy-based damage model and the discrete element-based model.Finally,some ambiguous questions and prospective research are interpreted and discussed.

关键词： cyclic loads Mechanical properties Damage evolution Fatigue failure Constitutive relationship

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缺口试件在压缩循环载荷下的疲劳行为研究

大连理工大学学报 1996年第6期 30-33页

作者： Chen Ruifeng, Chen Haoran, Ren Mingfa ( Research Institute of Engineering Mechanics, DUT ) He Yuting, Fu Xiangjiong ( Northwestern Polytechnical University )

缺口试件在压缩循环载荷下的疲劳行为研究... 详细信息

缺口试件在压缩循环载荷下的疲劳行为研究...

关键词： compression loads cyclic loads cracks residual stress tension