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Frontiers of Structural and Civil Engineering

ISSN 2095-2430 (Print)
ISSN 2095-2449 (Online)
CN 10-1023/X
Postal Subscription Code 80-968
2019 Impact Factor: 1.68

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Development of a seismic design method based on response spectra for building structures
ZHOU Xiyuan, YU Ruifang
Front. Struct. Civ. Eng.. 2007, 1 (2): 129-141.
Abstract   PDF (505KB)
The assumption and problem of the mode-superposition response spectrum method in seismic design code is discussed based on a brief review of the development of the seismic design method for building structures. The scope of application for the classical damping theory is analyzed and the necessity of the research on mode-superposition method for non-classical damping is presented. The progresses on the mode superposition response spectrum theory are discussed. This includes: 1) the complex mode superposition method (in real form) for the non-classically damped linear system and the general calculation formula for the application of code; 2) the complex complete quadratic combination (CCQC) method for the non-classically damped linear system, which is based on the same assumptions as in deducing the complete quadratic combination (CQC) method which is popularly used in seismic design codes of many countries; 3) the complex complete quadratic combination with three components (CCQC3) method, which is a generalization of the CCQC method to the case of multi-components and multiple-support seismic excitations and deducing corresponding method; 4) the approach for calculation of seismic response of the non-classically damped system with overcritical damping and the calculation method of seismic response for the linear system with multiple eigenvalues; 5) the time-dependent CCQC (t) algorithm considering nonstationary earthquake ground motion; 6) an applied and effective method to solve the low order complex vector basis for the large linear non-classically damped system, which can be expediently used in practice to avoid the unknown errors coming from the forced uncoupling method; 7) bringing forward the concept of partial quadratic combination in order to reduce the calculation amount of CQC and CCQC methods, and studying the primary estimation-criterion. The reasonability and applicable scope of these methods are also briefly discussed in this paper.
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Environmental problems of vibrations induced by railway traffic
XIA He, CAO Yanmei, De Roeck Guido, Degrande Geert
Front. Struct. Civ. Eng.. 2007, 1 (2): 142-152.
Abstract   PDF (909KB)
In this paper, a general review is made on the problems of vibrations of the ground and nearby buildings induced by railway traffic, and on the researches on this subject in theoretical analyses, numerical simulations, and field experiments. The characteristics of ground vibrations induced by railway traffic and their propagation, from the aspects of duration, intensity distribution, vehicle load and speed, are summarized. The vibration influences on the daily life of people, the operation of high-tech devices and the safety of buildings, and the vibration properties of subsoil and buildings adjacent to the underground, ground and elevated railway systems are introduced.
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Aerodynamic challenges in span length of suspension bridges
XIANG Haifan, GE Yaojun
Front. Struct. Civ. Eng.. 2007, 1 (2): 153-162.
Abstract   PDF (461KB)
The potential requirement of extreme bridge spans is firstly discussed according to horizontal clearances for navigation and economical construction of deep-water foundation. To ensure the technological feasibility of suspension bridges with longer spans, the static estimation of feasible span length is then made based on current material strength and weight of cables and deck. After the performances of the countermeasures for raising the aerodynamic stability are reviewed, a trial design of a 5 000 m suspension bridge, which is estimated as a reasonable limitation of span length, is finally conducted to respond to the tomorrow s challenge in span length of suspension bridges with the particular aspects, including dynamic stiffness, aerodynamic flutter and aerostatic stability.
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Modelling and experimental verification on concrete-filled steel tubular columns with L or T section
LU Xilin, LI Xueping, WANG Dan
Front. Struct. Civ. Eng.. 2007, 1 (2): 163-169.
Abstract   PDF (510KB)
Concrete-filled steel tubular columns with L or T sections were analyzed in this paper. According to the confining mechanism, the stress-strain constitutive model was put forward, and calculated results were compared with experimental records. After that, the hysteretic rules for the in-filled concrete were constructed, aiming at the analysis on the seismic behavior of composite members. The simulation analysis was performed by programming it in Fortran. The models in this paper can be applied in the program of time history analysis on tall buildings with concrete-filled steel tubular columns with L or T sections.
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Damage identification of a large-span concrete cable-stayed bridge based on genetic algorithm
ZHU Jinsong, XIAO Rucheng
Front. Struct. Civ. Eng.. 2007, 1 (2): 170-175.
Abstract   PDF (603KB)
The global stability of a structure, the stiffness of its main girder and concrete tower, and the variation of the forces of its stay cables are key issues to the safety assessment of an in-service cable-stayed bridge. The efficiency and rationality of local elaborate non-damage-identification could be enhanced by the primary damage identification of cable-stayed bridges on the basis of periodic detection of the cable force and strain monitor in key sections of the main girder. The genetic algorithms of damage identification for cable-stayed bridges were investigated in this paper on the basis of the monitor data of the cable force and strain in a key section of the main girder. A damage detection program for complex civil structure was generated to implement the identification of damage location and extent. The deterioration of the structure was calculated according to the variation of monitor data. It is demonstrated that the results of damage identification from the parametric finite element method are accurate. The method had been verified using a long-span concrete cable-stayed bridge in Ningbo, which has been in use for the past four years.
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Limit of axial force ratio and requirement for stirrups of RC columns with special shape
WANG Yiqun, XU Yidong, ZHAO Yanjing, CHEN Yunxia
Front. Struct. Civ. Eng.. 2007, 1 (2): 176-181.
Abstract   PDF (436KB)
Thousands of columns with special shape are analyzed by nonlinear numerical methods. The ductility is calculated to investigate the limit of the axial force ratio and circumstantial requirement for stirrups of an reinforced concrete (RC) column with special shape, in the point of view of the characteristic value for providing stirrup. The limit of the axial force ratio of columns with special shape in relation to the characteristic value of the stirrup is obtained. Then, the effect of stirrup arrangement on the ductility of the RC column is discussed in case of buckling of the longitudinal reinforcement and constraint concrete columns. The complete requirement for stirrups of RC column with special shape is given.
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Investigation of the structural form optimization methods of high-rise buildings
ZHANG Shihai, WANG Li, OU Jinping, WANG Guangyuan
Front. Struct. Civ. Eng.. 2007, 1 (2): 182-187.
Abstract   PDF (320KB)
In this paper, the structural form optimization methods of high-rise buildings based on the expert system (ES), case-based reasoning (CBR), and knowledge discovery in database (KDD) are evaluated systematically. The characteristics and shortcomings of each method are pointed out. It is predicted that the incorporation of these three techniques into an intelligent form optimization method will be an important development direction in the future. Finally, the unified intelligent form selection model combined with concepts of ES, CBR, KDD and artificially intelligent beautification is proposed. In consideration of the needs of human beings, machinery and computation, the model has been used for structural design combined with relevant knowledge, means, maneuver and strategy. The model plays an important role and has practical value in the process of artificially intelligent form optimization. It effectively reduces the blindness and failure of computer-aided structural design.
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Analyses of the seismic responses of soil layers with deep deposits
LOU Menglin, LI Yuchun, LI Nansheng
Front. Struct. Civ. Eng.. 2007, 1 (2): 188-193.
Abstract   PDF (452KB)
Several typical problems in the seismic response analysis of soil layers with deep deposits have been studied according to the seismic response analysis of the soil layer in the Shanghai region. The problems include the effect of the inclination of the bedrock under the soil layer on the seismic responses of the soil layer, the rationality of the artificial horizontal bedrock boundary in the soil layer, and the effect of the wave velocity of the bedrock and dynamic characteristics of the soil media on the seismic responses of the soil layer. Some results are obtained by numerical analysis. In the seismic response analysis, the effect of angle of inclination of the rock surface under the soil layer can be neglected if the angle is not more than two degrees. A significant error will be introduced in the calculation when the artificial horizontal rock surface is assumed in the soil layer according to the shear velocity of the soil media. The elasticity of the solid rock has little influence on the seismic response of the deep soil layer. The field investigation on the soil dynamic property should be paid more attention to.
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Design of a shaking table test box for a subway station structure in soft soil
YANG Linde, ZHENG Yonglai, ZHANG Dongliang, JI Qianqian, YANG Chao
Front. Struct. Civ. Eng.. 2007, 1 (2): 194-197.
Abstract   PDF (425KB)
A reasonable choice of structure of a model box is significant for a shaking table test to be successful in geotechnical engineering. A model box has been designed for the shaking table test of a subway station structure in the soft soil of Shanghai in the paper. The reasonable geometric similarity scale of the subway station structure has been determined by a 3-D dynamic analysis under the action of lateral equivalent static loading. The shape, size and structure of the model box are chosen by considering all the involved factors comprehensively. The shape of the box is similar to that of a typical station structure, and the ratio between the plane dimension of the model ground and that of the model structure is big enough to reduce the influence of boundary condition effectively. The structure is strong enough to avoid being demolished by shaking during a test. The contact conditions between the model soil and box are clear to help the data gained from the test well fit that from numerical analysis. The total weight of the model soil and box is less than the bearing capacity of the shaking table apparatus and there is no resonance between the model soil and box. The results show that the model box can be used to simulate the dynamic response of a subway station structure very well, so it provides a firm foundation for the success of the shaking table test of a subway station structure.
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Soil-water interaction in unsaturated expansive soil slopes
ZHAN Liangtong
Front. Struct. Civ. Eng.. 2007, 1 (2): 198-204.
Abstract   PDF (427KB)
The intensive soil-water interaction in unsaturated expansive soil is one of the major reasons for slope failures. In this paper, the soil-water interaction is investigated with the full-scale field inspection of rainwater infiltration and comprehensive experiments, including wetting-induced softening tests, swelling, and shrinkage tests. It is demonstrated that the soil-water interaction induced by seasonal wetting-drying cycles is very complex, and it involves coupled effects among the changes in water content, suction, stress, deformation and shear strength. In addition, the abundant cracks in the expansive soil play an important role in the soil-water interaction. The cracks disintegrate the soil mass, and more importantly, provide easy pathways for rainfall infiltration. Infiltration of rainwater not only results in wetting-induced softening of the shallow unsaturated soil layers, but also leads to the increase of horizontal stress. The increase of horizontal stress may lead to a local passive failure. The seasonal wetting-drying cycles tend to result in a down-slope creeping of the shallow soil layer, which leads to progressive slope failure.
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Analysis of nonlinear channel friction inverse problem
CHENG Weiping, LIU Guohua
Front. Struct. Civ. Eng.. 2007, 1 (2): 205-210.
Abstract   PDF (606KB)
Based on the Backus-Gilbert inverse theory, the singular value decomposition (SVD) for general inverse matrices and the optimization algorithm are used to solve the channel friction inverse problem. The resolution and covariance friction inverse model in matrix form is developed to examine the reliability of solutions. Theoretical analyses demonstrate that the convergence rate of the general Newton optimization algorithm is in the second-order. The Wiggins method is also incorporated into the algorithm. Using the method, noise can be suppressed effectively, and the results are close to accurate solutions with proper control parameters. Also, the numerical stability can be improved.
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Experimental study on flow behavior at open channel confluences
WANG Xiekang, WANG Xianye, LU Weizhen, LIU Tonghuan
Front. Struct. Civ. Eng.. 2007, 1 (2): 211-216.
Abstract   PDF (625KB)
Channel confluences are common in natural rivers and hydraulic engineering, and the flow behavior at confluences becomes very complex because of the interaction between the tributary and the main river. In this study, the experiments were performed in a combined flume with a 30º angle between the main and tributary flume located at Sichuan University. The velocity was measured by using a three-component acoustic Doppler velocimeter (ADV) over a grid defined throughout the junction region. Based on the analysis of the velocity at the confluence, the distinctive characteristics of a channel confluence flow may be divided into several zones including a zone of separation immediately downstream of the junction branch channel, the maximum and minimum velocity regions at the upstream and downstream in the confluent channel, and a shear plane developed between the two combining flows downstream of the confluent channel. In addition, secondary circulations in different directions at the higher and lower velocity zones are observed as well.
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Three-dimensional stability analysis of the dam foundation at Baise
XU Qianjun, LI Xu, CHEN Zuyu
Front. Struct. Civ. Eng.. 2007, 1 (2): 217-221.
Abstract   PDF (486KB)
It is usually difficult to determine the actual safety factors of rock masses in an ordinary two-dimensional stability analysis if the safety factors of the different cross sections in the rock mass vary significantly. In addition to the actual slope, arch dam abutment, and the actual foundation of a high building, another example is that the different cross sections of the foundation in the monolith of a gravity dam vary significantly, just like the condition at the overflow dam in the Baise project. A three-dimensional stability analysis method based on the upper-bound theorem was employed to solve this problem. The parameters used in the analysis were obtained from geomechanics tests, as well as continuity simulations of the randomly distributed joints. Two failure patterns against sliding are analyzed. One pattern is the foundation slide along deep-seated planes which were determined by calculations. The other pattern is the foundation slide along the planes across the bottom of the high steps in the foundation pit. The results indicate that a special overflow dam monolith can be considered to be safe in case of considering the three dimensional effect. However, a key wall with a depth of 5m must be constructed at the upper side of this monolith in order to ensure the safety of the foundation.
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Model test study for ice force on the bank-head of the lead-navigating bank
SONG An, SUN Jinliang, LU Hai, WANG Yi′an
Front. Struct. Civ. Eng.. 2007, 1 (2): 222-228.
Abstract   PDF (437KB)
To determine the bank-head s ice force of the lead-navigating bank at key position that faces the ice directly of certain water conservancy, ice model test in reduced scale is designed and carried out based on the local situation on the spot and data observed. Preliminary conclusions are got through the analysis of the experimental data such as effect of the ice velocity on the ice force , ratio of components of forces when ice sheet acting on the vertical bank-head, ice force ratio of vertical to 45? incline as well as ratio of level ice force to the vertical ice force when acting on 45? incline. Finally, suggestions on determination of the ice force using formula are given after comparison between the result calculated by the present formula of ice force and the experimental results.
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Development and utilization of underground space for the protection of relics in the Yang Emperor Mausoleum of the Han Dynasty
CHEN Zhilong, ZHANG Ping, LI Juxi
Front. Struct. Civ. Eng.. 2007, 1 (2): 229-233.
Abstract   PDF (439KB)
By analyzing the ten burials that have been unearthed at the Yang Emperor Mausoleum of the Han Dynasty, and China s first wholly underground protection and exhibition hall of relics that is under construction, the article expounds the importance of relic site protection through underground space. In particular, it discusses the preservation of historical and cultural relics, the harmonious relationship between architecture and nature, and the collection and security of cultural relics.
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Architecture design of Exit-Entry Administration Building of Shanghai Municipal Public Security Bureau
Front. Struct. Civ. Eng.. 2007, 1 (2): 234-239.
Abstract   PDF (908KB)
In retrospect of the architecture design of Exit-Entry Administration Building of Shanghai Municipal Public Security Bureau, this paper elaborates on the architect s pursuit of the symbol of the image, the fluidity of the space and the sequence of the function. It promotes a case which deals with the harmony of the architecture individuality and the urban space commonness in city center.
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Dynamic analyses of steel-reinforced super high-strength concrete columns
JIA Jinqing, JIANG Rui, XU Shilang, HOU Tong
Front. Struct. Civ. Eng.. 2007, 1 (2): 240-246.
Abstract   PDF (444KB)
The dynamic behaviors of steel-reinforced super high-strength concrete columns under seismic loading were studied with a series of experiments. Thirteen specimens, with concrete strengths ranging from 94.9 to 105.4 MPa and shear-span ratios of 2.75, were manufactured. The axial load ratio and the stirrup reinforcement ratio were the main experimental variables affecting the dynamic behavior of the specimens. The columns under low cyclic lateral loading mainly failed in the flexural-shear mode. Shear force-displacement hysteretic curves and skeleton curves were drawn. The coefficients of the specimens  displacement ductility were calculated. Experimental results indicate that ductility decreases while the axial load ratio increases, but it increases when the stirrup reinforcement ratio increases. The limit values of the axial load ratio and the minimum stirrup reinforcement ratio of the columns were investigated to satisfy definite ductility requirements. These values were suggested as references of engineering applications and of the amendment of the current Chinese design code of steel reinforced concrete composite structures.
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Experimental research on the mechanical property of prestressing steel wire during and after heating
ZHENG Wenzhong, HU Qiong, ZHANG Haoyu
Front. Struct. Civ. Eng.. 2007, 1 (2): 247-254.
Abstract   PDF (656KB)
The mechanical property of prestressing steel wire during and after heating is the key factor in the design of fire resistance and after-fire damage evaluation of prestressed structures. Tensile experiment of 16 prestressing steel wires ( fptk = 1770 N/mm2, d = 5 mm, low relaxation of stress) at high temperature and tensile experiment of 14 prestressed steel wires after heating are carried out. According to the experiment, the shapes of stress-strain curves of steel wire at high temperature go smooth and the mechanical property indexes of the steel wire such as strength, modulus of elasticity, etc., degenerate continuously as temperature increased. According to the experiment after heating, the mechanical property of steel wire varies little when the highest temperature that the steel wire has ever been heated to is lower than 300vH; while the stress-strain curves of steel wire become more ductile and the mechanical property indexes of the steel wire degenerate gradually when the highest temperature is higher than 300vH. By applying the theory of viscoelastic mechanics, stress-strain curves of steel wire at high temperatures without loading rate influence are obtained. The law of mechanical property indexes of the wire is presented. The mathematical models of the stress-strain relationship of the pre-stressed steel wire are established. All can serve as basic data for the analysis of fire resistance and after-fire damage evaluation of pre-stressed structures.
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The effects of festivals and special events on city image design
LIU Yuan, CHEN Chong
Front. Struct. Civ. Eng.. 2007, 1 (2): 255-259.
Abstract   PDF (258KB)
City marketing provides a good vehicle to strengthen a city in competition. On the analysis of the important roles of events and city image in the context of city marketing, this paper suggests that holding festivals or special events is an effective approach to enhance city marketing. The positive impacts of festivals and special events, such as the identification of city image, the promotion of the transmission of city image, and the reversal of the negative image of the city, are discussed. The negative impacts of festivals and special events are also talked about. The unique image of the city could be identified by the City Mind Identity, the City Visual Identity and the City Behavior Identity concerned with festivals and special events.
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19 articles