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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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Life cycle and performance based seismic design of major bridges in China
FAN Lichu
Front. Struct. Civ. Eng.. 2007, 1 (3): 261-266.
Abstract   PDF (360KB)
The idea of life cycle and performance based seismic design of major bridges is introduced. Based on the key components and non-key components of a bridge and the consideration of the inspectability, replaceability, reparability, controllability and retrofitability of the bridge components, different seismic design levels and expected performance objectives are suggested for the major bridges in China. The vulnerability analysis and progressive collapse analysis, as well as risk assessment, are also proposed to be the important issues to study in order to guide the seismic design of major bridges in the future.
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Seismic performance of viaducts with probabilistic method
ZHU Xi, WANG Jianmin
Front. Struct. Civ. Eng.. 2007, 1 (3): 267-273.
Abstract   PDF (635KB)
Due to the uncertainty of both ground motions and structural capacity, it is necessary to consider the seismic performance of viaduct structures using the probabilistic method. The risk is quantified by a procedure on the basis of a numerical determination of the fragility curves. A group of ground motions, Large Magnitude-Short Distance Bin (LMSR-N), selected specially due to its response spectra, is accorded well with the corresponding spectra of the Chinese code for seismic design. The characteristic values of the curvature ductility factors for the serviceability and the damage control limit states are obtained, and two equations for estimating the characteristic values of the curvature ductility factors are developed through regression analysis. Then, the serviceability and damage control limit states were proposed. Three damage states were constituted according the results of the experiment by Pacific Earthquake Engineering Research (PEER) Center. The analytical fragility curves were obtained specifically, using both Capacity Spectrum Method (CSM) (non-linear static) analysis and Ineremental Dynamic Method (IDM) (non-linear dynamic) analysis, respectively, in this paper. The structural fragility curves developed by CSM method can help make the structural analysis simple and quick, avoiding the implementation of the dynamic response history analysis (RHA). Although the dynamic RHA requires a lot of complicated analysis for the structure, the results from RHA are reliable and accurate. Fragility curves are powerful tools for use in performance-based seismic bridge design.
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Endochronic damage constitutive model for fully-graded aggregate mass concrete
SONG Yupu, WANG Huailiang
Front. Struct. Civ. Eng.. 2007, 1 (3): 274-280.
Abstract   PDF (482KB)
The behavior of deformation and strength of a fully-graded aggregate concrete under complex stress state is the basis of the nonlinear analysis and design for mass concrete structures such as concrete dams. In this paper, based on the combined endochronic theory with damage mechanics and on the quantities of experimental data, an endochronic damage constitutive model suitable for various aggregate grade concrete is proposed. This model takes into consideration the scale effect and the effect of wet screen sieve of aggregate in which the concept of yield surface is not needed and the difference of damage evolution rule of various graded aggregate concrete is a concern. The proposed model is used to analyze the deformation and strength of fully-graded aggregate mass concrete and the wet screened aggregate concrete specimens. The calculated results are in good agreement with experimental data, which can be used as a guide for the design of arch dams and other mass concrete structures.
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Experimental study of modal parameter identification in a simulated ambient-excited structure
JI Xiaodong, QIAN Jiaru, XU Longhe
Front. Struct. Civ. Eng.. 2007, 1 (3): 281-285.
Abstract   PDF (602KB)
Structure modal parameter online identification was used to monitor the structural health as evidenced by changes in the vibration characteristics. The natural excitation technique and the eigensystem realization algorithm were combined to identify the modal parameters in the time domain of a structure excited by simulated ambient vibrations. The mass-normalized mode shapes were obtained from the eigen-sensitivity analysis. The experimental modal analysis was performed on a two-story steel braced frame model excited by simulated ambient vibrations and hammer impacts. The mass-normalized mode shapes were acquired by changing the structural mass and by eigen-sensitivity analy sis. From finite element analysis results and the experimental data, it is shown that this method is effective.
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Theoretical analysis and actual experimental research on static characteristics of suspendome structure
CHEN Zhihua, YAN Xiangyu, SUN Ruirui, FENG Zhenchang, QIN Yali, ZHAO Jianbo
Front. Struct. Civ. Eng.. 2007, 1 (3): 286-292.
Abstract   PDF (675KB)
The suspendome used as the roof of the VIP hall in Tianjin Museum was analyzed by ANASYS under the assumptions of hinged joints and rigid joints in up chord, respectively, and the results show that the member force and nodal displacement under the two assumptions have little difference. Thus, it is attained that the suspendome can be analyzed with the assumption of hinged joints. A full-scale test on the suspendome with half-cable and half-pipe was carried out. The loading system, arrangement of measuring points, and the test procedures are introduced. Also, a test on steel wire ropes for elastic module was carried out. The experimental and theoretical values of member forces and nodal displacements were compared and it showed that they accord well with each other under low-level load. While under high-level load, the experimental value was bigger than the theoretical value due to the influence of the test environment. With the increase of the load, tension of outside cables and looseness of inside cables occurred, which indicated that the prestressing value in inside cables should be properly assigned. Both the experimental and theoretical results verify that the suspendome has a wide application prospect with the advantages of perfect mechanical characteristics, low steel consumption, convenient construction and low cost.
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An analytical method for calculating torsional constants for arbitrary complicated thin-walled cross-sections
DU Baisong, GE Yaojun, ZHOU Zheng
Front. Struct. Civ. Eng.. 2007, 1 (3): 293-297.
Abstract   PDF (493KB)
In this paper, an analytical method is proposed for calculating torsional constants for complicated thin-walled cross-sections with arbitrary closed or open rib stiffeners. This method uses the free torsional theory and the principle of virtual work to build governing equilibrium equations involving unknown shear flows and twisting rate. After changing the form of the equations and combining these two unknowns into one, torsional function, which is a function of shear flow, shear modulus, and twisting rate, is included in the governing equations as only one of the unknowns. All the torsional functions can be easily obtained from these homogeneous linear equations, and torsional constants can be easily obtained from the torsional functions. The advantage of this method is that we can easily and directly obtain torsional constants from the torsional functions, rather than the more sophisticated shear flow and twisting rate calculations. Finally, a complicated thin-walled cross-section is given as a valid numerical example to verify the analytical method, which is much more accurate and simpler than the traditional finite element method.
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Flutter control effect and mechanism of central-slotting for long-span bridges
YANG Yongxin, GE Yaojun, XIANG Haifan
Front. Struct. Civ. Eng.. 2007, 1 (3): 298-304.
Abstract   PDF (612KB)
The flutter control effect and mechanism of central-slotting, which have gradually been adopted in the design and construction of long-span bridges as an effective flutter controlling measure, were investigated with theoretical analysis and wind tunnel test. Five basic girder cross-sections representing five typical aerodynamic configurations were selected and central-slotted with two different slot widths. Then, a series of sectional model tests and theoretical analyses based on the two-dimensional three-degrees-of-freedom coupling flutter analysis method (2 dimension-3 degrees of freedom method, 2d-3DOF method) were carried out to investigate the aerodynamic performance, flutter mechanism and flutter modality of the five basic sections and their corresponding central-slotted sections. The results show that central-slotting can not always improve the aerodynamic stability of bridge structure. The control effect of central-slotting depends on the aerodynamic configuration of the original girder section and the corresponding central-slotting width. If the original section is inappropriate or the slot width is unsuitable, central-slotting will even deteriorate the structural flutter performance. Theoretical investigations indicated that the differences in flutter control effects come from the different formation and evolution of aerodynamic damping, and flutter modality especially the participation level of heaving motion also has a significant influence on the control effect of central-slotting.
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Experimental research on the creep behavior and bearing capacity of repeatedly prestressed concrete beam
SHAO Xudong, LI Lifeng, YANG Jianjun
Front. Struct. Civ. Eng.. 2007, 1 (3): 305-311.
Abstract   PDF (685KB)
In the prestress tensioning process of medium or short span prestressed concrete beam bridges, there are always many serious problems, such as the camber of straight beam being too large, curved beam going crosswise, and columns of rigid beam bridge cracking, that can be commonly seen because of its greater additional stress in prestressing. To solve the above problems, a new concept of repeatedly prestressed bridge structure was innovatively proposed in this work. It was proved, through theoretical and experimental comparison between this new structure and the traditional prestressed structure, that the application of repeated prestressing technology can greatly improve the mechanical and deformational performance of the low height beam during construction and long-term use. Furthermore, a kind of computational formula to calculate creep strain and deformation due to repeated prestressing in terms of time t was derived in this paper and the bearing capacity of this new structure has been tested. Finally, the work concludes that there is a bright application prospect for this new structure for medium and short span prestressed beam bridges to control deformations.
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Experiments on channel columns with inclined simple edge stiffeners under compression loading
WANG Chungang, ZHANG Yaochun, ZHANG Zhuangnan
Front. Struct. Civ. Eng.. 2007, 1 (3): 312-321.
Abstract   PDF (544KB)
In order to investigate the compression behavior of pin-ended cold-formed channel columns with inclined simple edge stiffeners, a total of 30 pin-ended cold-formed channel columns with three sections (sloping lip stiffener turned at 45º, 90º, and 135º to the flange, respectively) and three different lengths (500 mm, 1 250 mm, and 2 000 mm) were tested. It was found that the inclination angles and loading positions have an obvious effect on compression ultimate load-carrying capacities and failure modes. All three sections have certain post-buckling strength, and the failure modes of most of the specimens contained distortional buckling. The capacity of the specimens with 45º inclined angle for bearing compression is appreciably higher than the other two types of specimens with 90º or 135º inclined angles at the same negative eccentricity, but obviously lower than the other two at the same positive eccentricity. Furthermore, tests were simulated by finite element analysis. Results from the analysis are in great agreement with the experimental data.
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Solutions for a completely saturated porous elastic solid with impeded boundaries
CHEN Yunmin, LING Daosheng, ZHU Bin, CHENG Zehai
Front. Struct. Civ. Eng.. 2007, 1 (3): 322-328.
Abstract   PDF (517KB)
Analytical solutions are presented for the consolidation of a semi-infinite stratum and a finite soil layer with an impeding layer located on the surface subjected to a vertical point loading. The Laplace transform and the Hankel transform are used with respect to time and the radial coordinate, respectively. Solutions of other distributed loadings, including the circular loading, can be easily obtained by integrating those of the point loading. The consolidation degree, excess pore water pressure, vertical total stress, and the shear stress of the consolidating layer are analyzed in this study. The consolidation rate decreases with the increase in the thickness of the impeding layer. Stresses of the consolidating layer vary during the consolidation due to the coupling of the excess pore water dissipation and the soil skeleton deformation. Further, the Mandel-Cryer effect is also analyzed in this study.
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Unified solution of limit loads of thick wall cylinder subject to external pressure considering strain softening
CHEN Changfu, XIAO Shujun, YANG Yu
Front. Struct. Civ. Eng.. 2007, 1 (3): 329-333.
Abstract   PDF (501KB)
Based on the unified strength theory [1], a unified strength criterion for strain softening materials, such as concrete or rock, was derived, and the elastic and plastic limit loads of a thick-walled cylinder made of these materials subject to external pressure were also given. In addition, the influence of some factors on the limit loads of such cylinders as the ratio of the external radius to internal radius,rb/ra, the coefficient b, which reflects the effect of medium principal stress and the normal stress of the relevant surface on the material destroy degree, the ratio of tensile strength to compressed strength of the material, α, and the damage variable β>/em> were discussed in detail. Some examples were given and some meaningful results were obtained.
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Three-dimensional modeling of borehole data cored from engineering rock mass
HE Manchao, LI Xueyuan, LIU Bin, XU Nengxiong
Front. Struct. Civ. Eng.. 2007, 1 (3): 334-339.
Abstract   PDF (499KB)
Vast data from the drilling and geophysical prospecting are reliable original information to describe the space state of engineering rock mass, and one of the main difficulties in three-dimensional (3D) modeling of engineering rock mass is the processing of the primary data. From the viewpoint of 3D modeling, the engineering rock masses are classified as four basic types according to their geometric characteristics of geologic structure: (1) continuum rock mass; (2) discontinuous rock mass; (3) overturned fold rock mass and (4) intrusive rock mass. Because drilling data are very important to describe the characters of multi-scale of the spatial data for rock mass, the rule of how to process drilling data is developed to help appropriately display them in the viewpoint of 3D space. According to the characteristics of rock mass layers, the processing method of drilling data for 3D modeling of engineering rock masses, along with the layer thicknesses, is also proposed, including the evaluation rules and the extensive direction for original borehole data. By this method, the typical 3D data modeled is completed and the model form of the engineering rock mass is developed. By this example, it is finally verified that the method presented is successful and feasible to process 3D engineering rock mass.
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An efficient method for the dynamic interaction of open structure-foundation systems
LIU Jingbo, GU Yin, LI Bin, WANG Yan
Front. Struct. Civ. Eng.. 2007, 1 (3): 340-345.
Abstract   PDF (487KB)
The structure-foundation system is transformed from an original open system into an approximately hermetic system through a viscous-spring artificial boundary. In addition, the seismic wave scattering problem is changed to a wave source problem by employing an equivalent seismic wave input method. Subsequently, the modal superposition method is adopted to solve the approximated hermetic system. This procedure is highly efficient in analyzing dynamic structure-foundation interaction problems in the time domain. Two numerical examples are presented to illustrate the characteristics of the proposed method: one is a wave source problem in 2-dimensions (2-D) elastic semi-infinite space, and the other is a dynamic structure-foundation interaction problem under seismic excitations. Compared with the traditional direct step-by-step integration method, the proposed method, with a sufficient number of modes included, can significantly reduce the computational time with almost the same precision. The results also indicate that the proposed method is more advantageous for solving large structure-foundation systems of many degrees of freedom.
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Shaking table testing of hard layered soil-pile-structure interaction system
LI Peizhen, REN Hongmei, LU Xilin, SONG Heping, CHEN Yueqing
Front. Struct. Civ. Eng.. 2007, 1 (3): 346-352.
Abstract   PDF (462KB)
Shaking table tests on a dynamic interaction system of hard layered soil, pile foundation and frame structure were carried out. The earthquake damage of the superstructure and foundation was reproduced. Based on these tests, several key issues about the seismic response of the dynamic soil-structure interaction (SSI) system were studied. The natural frequency of the system was less than that of the structure on rigid foundation if the SSI is not taken into account, while its damping ratio was larger than that of the structure. The mode shape of the system was different from that of the structure on the fixed base in that there were rocking and swinging at the foundation. Magnification or reduction of vibration transferred by soil was related to soil characteristic, excitation magnitude, and so on. Generally, sand magnifies vibration, while viscous powder soil dampens vibration. The components of the acceleration response at the top of the superstructure were based on the relative magnitude of the rocking stiffness, the swing stiffness of the foundation and the stiffness of the super-structure. The multi-direction excitations have little effect on the key issues of the horizontal SSI.
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Shaking table test of composite foundation reinforcement of saturated silty soil for high speed railway
JIANG Guanlu, LIU Xianfeng, ZHANG Jianwen, ZHAO Ruyi
Front. Struct. Civ. Eng.. 2007, 1 (3): 353-360.
Abstract   PDF (717KB)
Three shaking table model tests were conducted with a geometrical scale of 1:10 using a large-scale laminar shear box to investigate the reinforcement effects of compacted gravel column-net composite foundation and cement fly-ash gravel (CFG) column-net composite foundation on the saturated silty soil along the Beijing-Shanghai High Speed Railway. The research results indicate that the increase in excess pore water pressure can be restrained effectively by the compacted gravel column-net composite foundation to improve the anti-liquefaction ability of the ground, and that shear displacement of the ground can be reduced greatly by the compacted gravel column-net and CFG column-net composite foundations to improve the capability of resisting shear displacement of ground. Furthermore, the amplifying of response acceleration, induced by foundation liquefaction, and the settlement of foundation and subgrade can be reduced greatly by the compacted gravel column-net and CFG column-net composite foundations to improve the aseismatic property of the foundation and subgrade.
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Analytical method of capsizing probability in the time domain for ships in the random beam seas
LIU Liqin, TANG Yougang, LI Hongxia
Front. Struct. Civ. Eng.. 2007, 1 (3): 361-366.
Abstract   PDF (689KB)
The methods for constructing safe basins of ships and predicting their survival probability in random waves were studied. The nonlinear differential equation of the rolling motion of ships in random beam seas was established considering nonlinear damping, nonlinear restoring moment, and random waves. The random rolling differential equation was solved in the time domain by applying the harmonic acceleration method and by synthetically considering the instantaneous state of ships and the narrowband wave energy spectrum. The numerical simulation of random capsizing course was brought forward, the safe basins were constructed for safe navigation, and the survival probabilities of ships were calculated. As an example, the safe basins on the rolling initial value plane were constructed for a 30.27-meter-long fishing vessel according to different initial conditions and random wave parameters. The survival probabilities of the fishing vessel under different significant wave heights were predicted. Thus, the survival probabilities of ships in random seas can be predicted quantitatively by the proposed method.
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Building information modeling based on intelligent parametric technology
ZENG Xudong, TAN Jie
Front. Struct. Civ. Eng.. 2007, 1 (3): 367-370.
Abstract   PDF (254KB)
In order to push the information organization process of the building industry, promote sustainable architectural design and enhance the competitiveness of China’s building industry, the author studies building information modeling (BIM) based on intelligent parametric modeling technology. Building information modeling is a new technology in the field of computer aided architectural design, which contains not only geometric data, but also the great amount of engineering data throughout the lifecycle of a building. The author also compares BIM technology with two-dimensional CAD technology, and demonstrates the advantages and characteristics of intelligent parametric modeling technology. Building information modeling, which is based on intelligent parametric modeling technology, will certainly replace traditional computer aided architectural design and become the new driving force to push forward China s building industry in this information age.
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Feasibility analysis of mixed-income housing in China
TIAN Ye, BI Xiangyang, LI Dexiang
Front. Struct. Civ. Eng.. 2007, 1 (3): 371-377.
Abstract   PDF (322KB)
In this paper, it is demonstrated that mixed-income housing is a feasible and beneficial pattern nowadays. This pattern is propitious for good living and harmonious development of society. Based on practice, data are gathered from the field, and the social investment and social distance analysis of the social network theory are used from the perspective of cross-disciplinary fields. The hypothesis is tested and the feasible and beneficial characteristics of mixed-income housing are pointed out.
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18 articles