Frontiers of Structural and Civil Engineering

ISSN 2095-2430 (Print)
ISSN 2095-2449 (Online)
CN 10-1023/X
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Modern developments related to nanotechnology and nanoengineering of concrete
Konstantin SOBOLEV
Front. Struct. Civ. Eng.    2016, 10 (2): 131-141.   https://doi.org/10.1007/s11709-016-0343-0
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This paper reports on modern developments related to nanotechnology of cement and concrete. Recent advances in instrumentation and design of advanced nano-composite materials is discussed. New technological directions and historical milestones in nanoengineering and nanomodi?cation of cement-based materials are presented. It is concluded that there is a strong potential of nanotechnology to improve the performance of cement-based materials.

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Cited: Crossref(22) WebOfScience(17)
A concept of capillary active, dynamic insulation integrated with heating, cooling and ventilation, air conditioning system
Mark BOMBERG
Front Arch Civil Eng Chin    2010, 4 (4): 431-437.   https://doi.org/10.1007/s11709-010-0071-9
Abstract   HTML   PDF (213KB)

When a historic fa?ade needs to be preserved or when the seismic considerations favor use of a concrete wall system and fire considerations limit exterior thermal insulation, one needs to use interior thermal insulation systems. Interior thermal insulation systems are less effective than the exterior systems and will not reduce the effect of thermal bridges. Yet they may be successfully used and, in many instances, are recommended as a complement to the exterior insulation. This paper presents one of these cases. It is focused on the most successful applications of capillary active, dynamic interior thermal insulation. This happens when such insulation is integrated with heating, cooling and ventilation, air conditioning (HVAC) system. Starting with a pioneering work of the Technical University in Dresden in development of capillary active interior insulations, we propose a next generation, namely, a bio-fiber thermal insulation. When completing the review, this paper proposes a concept of a joint research project to be undertaken by partners from the US (where improvement of indoor climate in exposed coastal areas is needed), China (indoor climate in non-air conditioned concrete buildings is an issue), and Germany (where the bio-fiber technology has been developed).

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Experimental study on behavior of mortar-aggregate interface after elevated temperatures
Wan WANG, Jianzhuang XIAO, Shiying XU, Chunhui WANG
Front. Struct. Civ. Eng.    2017, 11 (2): 158-168.   https://doi.org/10.1007/s11709-016-0374-6
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A push-out test program was designed and conducted to study the meso-scale behavior of mortar-aggregate interface for concrete after elevated temperatures ranging from 20°C to 600°C with the concept of modeled concrete (MC) and modeled recycled aggregate concrete (MRAC). The MCs and MRACs were designed with different strength grade of mortar and were exposed to different elevated temperatures. Following that the specimens were cooled to room temperature and push-out tests were conducted. Failure process and mechanical behaviors were analyzed based on failure modes, residual load-displacement curves, residual peak loads and peak displacements. It is found that failure modes significantly depended on specimen type, the elevated temperature and the strength grade of mortar. For MC, major cracks started to propagate along the initial cracks caused by elevated temperatures at about 80% of residual peak load. For MRAC, the cracks appeared at a lower level of load with the increasing elevated temperatures. The cracks connected with each other, formed a failure face and the specimens were split into several parts suddenly when reaching the residual peak load. Residual load-displacement curves of different specimens had similarities in shape. Besides, effect of temperatures and strength grade of mortar on residual peak load and peak displacement were analyzed. For MC and MRAC with higher strength of new hardened mortar, the residual peak load kept constant when the temperature is lower than 400°C and dropped by 43.5% on average at 600°C. For MRAC with lower strength of new hardened mortar, the residual peak load began to reduce when the temperatures exceeded 200°C and reduced by 27.4% and 60.8% respectively at 400°C and 600°C. The properties of recycled aggregate concrete (RAC) may be more sensitive to elevated temperatures than those of natural aggregate concrete (NAC) due to the fact that the interfacial properties of RAC are lower than those of NAC, and are deteriorated at lower temperatures.

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Probabilistic safety assessment of self-centering steel braced frame
Navid RAHGOZAR, Nima RAHGOZAR, Abdolreza S. MOGHADAM
Front. Struct. Civ. Eng.    2018, 12 (1): 163-182.   https://doi.org/10.1007/s11709-017-0384-z
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The main drawback of conventional braced frames is implicitly accepting structural damage under the design earthquake load, which leads to considerable economic losses. Controlled rocking self-centering system as a modern low-damage system is capable of minimizing the drawbacks of conventional braced frames. This paper quantifies main limit states and investigates the seismic performance of self-centering braced frame using a Probabilistic Safety Assessment procedure. Margin of safety, confidence level, and mean annual frequency of the self-centering archetypes for their main limit states, including PT yield, fuse fracture, and global collapse, are established and are compared with their acceptance criteria. Considering incorporating aleatory and epistemic uncertainties, the efficiency of the system is examined. Results of the investigation indicate that the design of low- and mid-rise self-centering archetypes could provide the adequate margin of safety against exceeding the undesirable limit-states.

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Modeling of alkali-silica reaction in concrete: a review
J.W. PAN, Y.T. FENG, J.T. WANG, Q.C. SUN, C.H. ZHANG, D.R.J. OWEN
Front Struc Civil Eng    2012, 6 (1): 1-18.   https://doi.org/10.1007/s11709-012-0141-2
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This paper presents a comprehensive review of modeling of alkali-silica reaction (ASR) in concrete. Such modeling is essential for investigating the chemical expansion mechanism and the subsequent influence on the mechanical aspects of the material. The concept of ASR and the mechanism of expansion are first outlined, and the state-of-the-art of modeling for ASR, the focus of the paper, is then presented in detail. The modeling includes theoretical approaches, meso- and macroscopic models for ASR analysis. The theoretical approaches dealt with the chemical reaction mechanism and were used for predicting pessimum size of aggregate. Mesoscopic models have attempted to explain the mechanism of mechanical deterioration of ASR-affected concrete at material scale. The macroscopic models, chemo-mechanical coupling models, have been generally developed by combining the chemical reaction kinetics with linear or nonlinear mechanical constitutive, and were applied to reproduce and predict the long-term behavior of structures suffering from ASR. Finally, a conclusion and discussion of the modeling are given.

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Research review of the cement sand and gravel (CSG) dam
Xin CAI, Yingli WU, Xingwen GUO, Yu MING
Front Struc Civil Eng    2012, 6 (1): 19-24.   https://doi.org/10.1007/s11709-012-0145-y
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The cement sand and gravel (CSG) dam is a new style of dam that owes the advantages both of the concrete faced rock-fill dam (CRFD) and roller compacted concrete (RCC) gravity dam, because of which it has attracted much attention of experts home and abroad. At present, some researches on physic-mechanical property of CSG material and work behavior of CSG dam have been done. This paper introduces the development and characteristics of CSG dam systematically, and summarizes the progress of the study on basic tests, constitutive relation of CSG material and numerical analysis of CSG dam, in addition, indicates research and application aspect of the dam.

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Numerical study of the cyclic load behavior of AISI 316L stainless steel shear links for seismic fuse device
Ruipeng LI,Yunfeng ZHANG,Le-Wei TONG
Front. Struct. Civ. Eng.    2014, 8 (4): 414-426.   https://doi.org/10.1007/s11709-014-0276-4
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This paper presents the results of nonlinear finite element analyses conducted on stainless steel shear links. Stainless steels are attractive materials for seismic fuse device especially for corrosion-aware environment such as coastal regions because they are highly corrosion resistant, have good ductility and toughness properties in combination with low maintenance requirements. This paper discusses the promising use of AISI 316L stainless steel for shear links as seismic fuse devices. Hysteresis behaviors of four stainless steel shear link specimens under reversed cyclic loading were examined to assess their ultimate strength, plastic rotation and failure modes. The nonlinear finite element analysis results show that shear links made of AISI 316L stainless steel exhibit a high level of ductility. However, it is also found that because of large over-strength ratio associated with its strain hardening process, mixed shear and flexural failure modes were observed in stainless steel shear links compared with conventional steel shear links with the same length ratio. This raises the issue that proper design requirements such as length ratio, element compactness and stiffener spacing need to be determined to ensure the full development of the overall plastic rotation of the stainless steel shear links.

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Shear design of high strength concrete prestressed girders
Emad L. LABIB,Hemant B. DHONDE,Thomas T. C. HSU,Y. L. MO
Front. Struct. Civ. Eng.    2014, 8 (4): 373-387.   https://doi.org/10.1007/s11709-014-0087-7
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Normal strength prestressed concrete I-girders are commonly used as the primary superstructure components in highway bridges. However, shear design guidelines for high strength PC girders are not available in the current structural codes. Recently, ten 7.62 m (25 feet) long girders made with high strength concrete were designed, cast, and tested at the University of Houston (UH) to study the ultimate shear strength and the shear concrete contribution (Vc) as a function of concrete strength (f\hskip -3ptc). A simple semi-empirical set of equations was developed based on the test results to predict the ultimate shear strength of prestressed concrete I-girders. The UH-developed set of equations is a function of concrete strength (f\hskip -3ptc), web area (bwd), shear span to effective depth ratio (a/d), and percentage of transverse steel (ρt). The proposed UH-Method was found to accurately predict the ultimate shear strength of PC girders with concrete strength up to 117 MPa (17000 psi) ensuring satisfactory ductility. The UH-Method was found to be not as overly conservative as the ACI-318 (2011) code provisions, and also not to overestimate the ultimate shear strength of high strength PC girders as the AASHTO LRFD (2010) code provisions. Moreover, the proposed UH-Method was found fairly accurate and not exceedingly conservative in predicting the concrete contribution to shear for concrete strength up to 117 MPa (17000 psi).

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Safety and serviceability assessment for high-rise tower crane to turbulent winds
Zhi SUN, Nin HOU, Haifan XIANG
Front Arch Civil Eng Chin    2009, 3 (1): 18-24.   https://doi.org/10.1007/s11709-009-0009-2
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Tower cranes are commonly used facilities for the construction of high-rise structures. To ensure their workability, it is very important to analyze their response and evaluate their condition under extreme conditions. This paper proposes a general scheme for safety and serviceability assessment of high-rise tower crane to turbulent winds based on time domain buffeting response analysis. Spatially correlated wind velocity field at the location of the tower crane was first simulated using an algorithm for generating the time domain samples of a stationary, multivariate stochastic process according to some prescribed spectral density matrix. The buffeting forces applied to the structure were computed according to the above-simulated wind velocity fluctuations and the lift, drag, and moment coefficients obtained from a CFD computation. Those spatially correlated loads were then fed into a well calibrated finite element model and the nonlinear time history analysis was conducted to compute structural buffeting response. Compared with structural on-site response measurement, the computed response using the proposed method has good precision. The proposed method is then adopted for analyzing the buffeting response of an in-use tower crane under the design wind speed and the maximum operational wind speed for safety and serviceability assessment.

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Study of bond strength between various grade of Ordinary Portland Cement (OPC) and Portland Pozzolane Cement (PPC) mixes and different diameter of TMT bars by using pullout test
A D POFALE, S P WANJARI
Front Struc Civil Eng    2013, 7 (1): 39-45.   https://doi.org/10.1007/s11709-013-0193-y
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Since last two decades, the Portland Pozzolane Cement (PPC) is extensively used in structural concrete. But, till to date, a few literature is available on bond strength of concrete using PPC mixes. There are many literatures available on bond strength of concrete mixes using Ordinary Portland Cement (OPC). Hence, a comparative study was conducted on bond strength between OPC and PPC mixes. In the present investigation, total 24 samples consisting of M20, M35 and M50 grades of concrete and 16 and 25 mm diameter of TMT bar were tested for 7 and 28 days. The pullout bond test was conducted on each specimen as per IS: 2770-1967/1997 [1] and the results were observed at 0.25 mm slip at loaded end called as critical bond stress and at maximum bond load called as maximum bond stress. It was observed that the critical bond strength of PPC mixes is 10% higher than OPC mixes. Whereas, marginal improvement was noticed in maximum bond strength of PPC mixes. Hence, based on these findings, it could be concluded that development length for PPC mixes could be reduced by 10% as compared with same grade of OPC mixes.

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Dynamic analysis of rail transit elevated bridge with ladder track
He XIA, Yushu DENG, Yongwei ZOU, Guido DE ROECK, Geert DEGRANDE
Front Arch Civil Eng Chin    2009, 3 (1): 2-8.   https://doi.org/10.1007/s11709-009-0001-x
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In this paper, a dynamic analysis model of an elevated bridge with ladder tracks under moving train load is established. The whole process of a train running through an elevated bridge at different speeds is simulated. The dynamic responses of the elevated bridge with ladder track and the running safety and comfort index of train vehicles are evaluated. Compared with the dynamic responses of an elevated bridge with ordinary non-ballasted slab track, the ladder track’s effect on reducing the vibration of an elevated bridge is analyzed. The analysis results show that the ladder track has good vibration reduction characteristics as compared to ordinary non-ballasted track.

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Shear-flexural strength mechanical model for the design and assessment of reinforced concrete beams subjected to point or distributed loads
Antonio MARÍ,Antoni CLADERA,Jesús BAIRÁN,Eva OLLER,Carlos RIBAS
Front. Struct. Civ. Eng.    2014, 8 (4): 337-353.   https://doi.org/10.1007/s11709-014-0081-0
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A mechanical model recently developed for the shear strength of slender reinforced concrete beams with and without shear reinforcement is presented and extended to elements with uniformly distributed loads, specially focusing on practical design and assessment in this paper. The shear strength is considered to be the sum of the shear transferred by the concrete compression chord, along the crack, due to residual tensile and frictional stresses, by the stirrups and, if they exist, by the longitudinal reinforcement. Based on the principles of structural mechanics simple expressions have been derived separately for each shear transfer action and for their interaction at ultimate limit state. The predictions of the model have been compared to those obtained by using the EC2, MC2010 and ACI 318-08 provisions and they fit very well the available experimental results from the recently published ACI-DAfStb databases of shear tests on slender reinforced concrete beams with and without stirrups. Finally, a detailed application example has been presented, obtaining each contributing component to the shear strength and the assumed shape and position of the critical crack.

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Cyclic stress-strain behavior of structural steel with yield-strength up to 460 N/mm2
Yiyi CHEN,Wei SUN,Tak-Ming CHAN
Front. Struct. Civ. Eng.    2014, 8 (2): 178-186.   https://doi.org/10.1007/s11709-014-0245-y
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This paper presents a constitutive model based on Ramberg-Osgood equation to describe the hysteresis material behavior of structural carbon steel with nominal yield strength between 235 to 420 N/mm2. The proposed model was calibrated against a series of cyclic material tests with strain amplitude varying from 0.5% to 2.0%. A simple relationship between the modular parameter K and the yield strength fy was proposed. The calibrated Ramberg-Osgood model revealed excellent agreement with the experimental results and captured further the experimental behavior of test specimens with nominal yield strength of 460 N/mm2. The proposed constitutive model was also adopted in conjunction with the combined kinematic/isotropic materials description in ABAQUS to mimic a full scale experimental test under cyclic loading. The numerical results revealed close agreement with the experimental observations.

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Behavior of compacted clay-concrete interface
R. R .SHAKIR, Jungao ZHU
Front Arch Civil Eng Chin    2009, 3 (1): 85-92.   https://doi.org/10.1007/s11709-009-0013-6
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Tests of interface between compacted clay and concrete were conducted systematically using interface simple shear test apparatus. The samples, having same dry density with different water content ratio, were prepared. Two types of concrete with different surface roughness, i.e., relatively smooth and relatively rough surface roughness, were also prepared. The main objectives of this paper are to show the effect of water content, normal stress and rough surface on the shear stress-shear displacement relationship of clay-concrete interface. The following were concluded in this study: 1) the interface shear sliding dominates the interface shear displacement behavior for both cases of relatively rough and smooth concrete surface except when the clay water content is greater than 16% for the case of rough concrete surface where the shear failure occurs in the body of the clay sample; 2) the results of interface shear strength obtained by direct shear test were different from that of simple shear test for the case of rough concrete surface; 3) two types of interface failure mechanism may change each other with different water content ratio; 4) the interface shear strength increases with increasing water content ratio especially for the case of clay-rough concrete surface interface.

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Optimization design of spar cap layup for wind turbine blade
Jie ZHU, Xin CAI, Pan PAN, Rongrong GU
Front Struc Civil Eng    2012, 6 (1): 53-56.   https://doi.org/10.1007/s11709-012-0147-9
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Based on the aerodynamic shape and structural form of the blade are fixed, a mathematical model of optimization design for wind turbine blade is established. The model is pursued with respect to minimum the blade mass to reduce the cost of wind turbine production. The material layup numbers of the spar cap are chosen as the design variables; while the demands of strength, stiffness and stability of the blade are employed as the constraint conditions. The optimization design for a 1.5 MW wind turbine blade is carried out by combing above objective and constraint conditions at the action of ultimate flapwise loads with the finite element software ANSYS. Compared with the original design, the optimization design result achieves a reduction of 7.2% of the blade mass, the stress and strain distribution of the blade is more reasonable, and there is no occurrence of resonance, therefore its effectiveness is verified.

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Strain localization analyses of idealized sands in biaxial tests by distinct element method
Mingjing JIANG, Hehua ZHU, Xiumei LI,
Front. Struct. Civ. Eng.    2010, 4 (2): 208-222.   https://doi.org/10.1007/s11709-010-0025-2
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This paper presents a numerical investigation on the strain localization of an idealized sand in biaxial compression tests using the distinct element method (DEM). In addition to the dilatancy and material frictional angle, the principal stress field, and distributions of void ratio, particle velocity, and the averaged pure rotation rate (APR) in the DEM specimen are examined to illustrate the link between microscopic and macroscopic variables in the case of strain localization. The study shows that strain localization of the granular material in the tests proceeds with localizations of void ratio, strain and APR, and distortions of stress field and force chains. In addition, both thickness and inclination of the shear band change with the increasing of axial strain, with the former valued around 10–14 times of mean grain diameter and the later overall described by the Mohr-Coulomb theory.
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3D finite element method (FEM) simulation of groundwater flow during backward erosion piping
Kristine VANDENBOER,Vera van BEEK,Adam BEZUIJEN
Front. Struct. Civ. Eng.    2014, 8 (2): 160-166.   https://doi.org/10.1007/s11709-014-0257-7
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Backward erosion piping is an important failure mechanism for cohesive water retaining structures which are founded on a sandy aquifer. At present, the prediction models for safety assessment are often based on 2D assumptions. In this work, a 3D numerical approach of the groundwater flow leading to the erosion mechanism of backward erosion piping is presented and discussed. Comparison of the 2D and 3D numerical results explicitly demonstrates the inherent 3D nature of the piping phenomenon. In addition, the influence of the seepage length is investigated and discussed for both piping initiation and piping progression. The results clearly indicate the superiority of the presented 3D numerical model compared to the established 2D approach. Moreover, the 3D numerical results enable a better understanding of the complex physical mechanism involved in backward erosion piping and thus can lead to a significant improvement in the safety assessment of water retaining structures.

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Vibration analysis of multi-walled carbon nanotubes embedded in elastic medium
Pattabhi R. BUDARAPU,Sudhir Sastry YB,Brahmanandam JAVVAJI,D. Roy MAHAPATRA
Front. Struct. Civ. Eng.    2014, 8 (2): 151-159.   https://doi.org/10.1007/s11709-014-0247-9
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We propose a method to estimate the natural frequencies of the multi-walled carbon nanotubes (MWCNTs) embedded in an elastic medium. Each of the nested tubes is treated as an individual bar interacting with the adjacent nanotubes through the inter-tube Van der Waals forces. The effect of the elastic medium is introduced through an elastic model. The mathematical model is finally reduced to an eigen value problem and the eigen value problem is solved to arrive at the inter-tube resonances of the MWCNTs. Variation of the natural frequencies with different parameters are studied. The estimated results from the present method are compared with the literature and results are observed to be in close agreement.

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From understanding to designing soundscapes
Jian KANG
Front Arch Civil Eng Chin    2010, 4 (4): 403-417.   https://doi.org/10.1007/s11709-010-0091-5
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Soundscape represents a step change in the field of environmental acoustics in that it combines physical, social, and psychological approaches. Although the term soundscape was introduced in the 1960s, significant attention to it has mainly been paid in the last decade or so in the community of environmental acoustics by researchers and recently by practitioners including policy makers. This paper explores the current situation and future challenges in soundscape. Starting with a framework on research and practical needs in soundscape and a brief introduction of some recent/current networks, activities, projects, and publications, this paper then presents a systematic review of recent progress in soundscape research and practice. A short review of the soundscape research in China is also given.

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Experimental study on concrete box culverts in trenches
Baoguo CHEN, Junjie ZHENG, Jie HAN
Front Arch Civil Eng Chin    2009, 3 (1): 73-80.   https://doi.org/10.1007/s11709-009-0008-3
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Concrete box culverts are widely used in expressways in mountain areas. Many problems frequently take place due to improperly estimated vertical earth pressures on culverts. The prevailing Chinese General Code for Design of Highway Bridges and Culverts (CGCDHBC) stipulates the computation of the design load on culverts primarily based on the linear earth pressure theory, which cannot accurately describe the variation of the vertical load on culverts in trenches. In this paper, a full-scale experiment and numerical simulation were conducted to evaluate the variation of vertical earth pressures on culvert and soil arching in backfill. The variations of foundation pressure and settlement were also analyzed. The result revealed that the soil arch forms when the backfill on the culvert reaches a certain height. The soil arching effect reduces the stress concentration on the crown of the culvert but it is unstable. The vertical earth pressure on top of the culvert is significantly different from that recommended by the CGCDHBC

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A study on quality evaluation for bituminous mixture using X-ray CT
Satoshi TANIGUCHI, Keiichiro OGAWA, Jun OTANI, Itaru NISHIZAKI
Front Struc Civil Eng    2013, 7 (2): 89-101.   https://doi.org/10.1007/s11709-013-0197-7
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The objective of this paper is to propose a new quality evaluation method for asphalt concrete mixture using X-ray CT scanner. To achieve this aim, asphalt mixtures should be subjected to the X-ray CT scanning and its characteristics should be clarified. The approach employed in this study was as follows: 1) Coarse aggregate, fine aggregate, filler and bitumen were prepared; 2) dense-graded, coarse-graded and porous asphalt mixtures were made; 3) materials and mixtures were subjected to the X-ray CT scanning; 4) frequency of CT-value, threshold value, average slice CT-value, average segment CT-value were computed. In the material examination, CT-value of aggregate becomes smaller in the order of coarse aggregate, fine aggregate and filler and CT image of bitumen was nearly homogeneous. In the mixture examination, histograms of CT-value and four segmentation images made from CT images expressed the material and mixture characterization such as particle size and the difference in bitumen content and mixture type visibly and the bitumen content varies with the threshold values. In addition, the average segment CT-value without threshold value by dividing the fine aggregate from the coarse aggregate and average CT-value of the coarse aggregate, especially is highly correlated with average CT-value of the bitumen.

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Urban design based on public safety-Discussion on safety-based urban design
Kaizhen CAI, Jianguo WANG
Front Arch Civil Eng Chin    2009, 3 (2): 219-227.   https://doi.org/10.1007/s11709-009-0023-4
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Because of public safety problems in construction of urban surroundings, this paper expounds the necessity of the study on public safety-based urban design in perspective of modern city. It brings forward the concept of safety-based urban design and attempts to explore the basic connotation and contents with framework for studies.

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Running train induced vibrations and noises of elevated railway structures and their influences on environment
He XIA, Fei GAO, Xuan WU, Nan ZHANG, Guido DE ROECK, Geert DEGRANDE
Front Arch Civil Eng Chin    2009, 3 (1): 9-17.   https://doi.org/10.1007/s11709-009-0010-9
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The vibrations and noises of elevated railway structures have been cause for concern due to their effects on the environment and the people living near elevated lines. In this paper, the main structural features of some new elevated bridges and station hall were introduced. The generation mechanism of vibrations and noise of elevated structures induced by trains were investigated. The noise induced by different types of elevated bridges, their influences on the environment and the theoretical method for the analysis of structure borne noise was analyzed. Finally, several field measurements on train induced noises at the platforms of elevated subway stations and bridges were presented.

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Simulation model based on Monte Carlo method for traffic assignment in local area road network
Yuchuan DU, Yuanjing GENG, Lijun SUN
Front Arch Civil Eng Chin    2009, 3 (2): 195-203.   https://doi.org/10.1007/s11709-009-0032-3
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For a local area road network, the available traffic data of traveling are the flow volumes in the key intersections, not the complete OD matrix. Considering the circumstance characteristic and the data availability of a local area road network, a new model for traffic assignment based on Monte Carlo simulation of intersection turning movement is provided in this paper. For good stability in temporal sequence, turning ratio is adopted as the important parameter of this model. The formulation for local area road network assignment problems is proposed on the assumption of random turning behavior. The traffic assignment model based on the Monte Carlo method has been used in traffic analysis for an actual urban road network. The results comparing surveying traffic flow data and determining flow data by the previous model verify the applicability and validity of the proposed methodology.

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Ribbon bridge in waves based on hydroelasticity theory
Cong WANG, Shixiao FU, Weicheng CUI
Front Arch Civil Eng Chin    2009, 3 (1): 57-62.   https://doi.org/10.1007/s11709-009-0005-6
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For the design and operation of a floating bridge, the understanding of its hydroelastic behavior in waves is of great importance. This paper investigated the hydroelastic performances of a ribbon bridge under wave action. A brief introduction on the estimation of dynamic responses of the floating bridge and the comparisons between the experiments and estimation were presented. Based on the 3D hydroelasticity theory, the hydroelastic behavior of the ribbon bridge modeled by finite element method (FEM) was analyzed by employing the mode superposition method. And the relevant comparisons between the numerical results and experimental data obtained from one tenth scale elastic model test in the ocean basin were made. It is found that the present method is applicable and adaptable for predicting the hydroelastic response of the floating bridge in waves.

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Field testing of geosynthetic-reinforced and column-supported earth platforms constructed on soft soil
Qiangong CHENG,Jiujiang WU,Dongxue ZHANG,Fengping MA
Front. Struct. Civ. Eng.    2014, 8 (2): 124-139.   https://doi.org/10.1007/s11709-014-0255-9
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This paper is focused on the behavior of geosynthetic-reinforced and column-supported (GRCS) earth platforms in soft soil. By analyzing the data of a 15-month long field monitoring project, the bearing behavior and effectiveness of GRCS earth platforms are discussed in detail. It can be found that the soil arching is generated when the filling reaches a certain height. The measured pressure acting on the soil in the center of four piles was smaller than that acting on the soil between two piles. The elongation and the tension of the geogrid located in the soil between piles are both larger than the corresponding values on the pile top. The skin friction of piles is relatively small in the soil layer with low strength and the load transfer of the axial force in those layers is significant; meanwhile, the opposite situation occurs in the soil layer with high strength. The pore water pressure at shallow locations increases slightly with the filling height and is greatly affected by the increasing filling load. The layered settlement is directly proportional to the filling height, and the corresponding amount is relevant to the locations and the properties of specific soil layers. Additionally, the lateral displacement of the embankment increases with greater loading and decreases with increased depth. These suggest that the use of GRCS system can reduce lateral displacements and enhance the stability of an embankment significantly.

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Calculation method on shape finding of self-anchored suspension bridge with spatial cables
Yan HAN, Zhengqing CHEN, Shidong LUO, Shankui YANG
Front Arch Civil Eng Chin    2009, 3 (2): 165-172.   https://doi.org/10.1007/s11709-009-0021-6
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Based on the spatial model, a reliable and accurate calculation method on the shape finding of self-anchored suspension bridge with spatial cables was studied in this paper. On the principle that the shape of the main cables between hangers is catenary, the iteration method of calculating the shapes of the spatial main cables under the load of hanger forces was deduced. The reasonable position of the saddle was determined according to the shape and the theoretical joint point of the main cables. The shapes of the main cables at completed cable stage were calculated based on the unchanging principle of the zero-stress lengths of the main cables. By using a numerical method combining with the finite element method, one self-anchored suspension bridge with spatial cables was analyzed. The zero-stress length of the main cables, the position of the saddle, and the pre-offsetting of the saddle of the self-anchored suspension bridge were given. The reasonable shapes of the main cables at bridge completion stage and completed cable stage were presented. The results show that the shape-finding calculation method is effective and reliable.

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Prediction of cyclic large plasticity for prestrained structural steel using only tensile coupon tests
Liang-Jiu JIA, Tsuyoshi KOYAMA, Hitoshi KUWAMURA
Front Struc Civil Eng    2013, 7 (4): 466-476.   https://doi.org/10.1007/s11709-013-0219-5
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Cold-formed steel members, which experience complicated prestrain histories, are frequently applied in structural engineering. This paper aims to predict cyclic plasticity of structural steels with tensile and compressive prestrain. Monotonic and cyclic tests on hourglass specimens with tensile and compressive prestrain are conducted, and compared with numerical simulations using the Chaboche model. Two approaches are taken in the simulation. The first requires only the monotonic tensile test data from the prestrained steels, and the second requires both the monotonic tensile test data from the virgin steel and the prestrain histories. The first approach slightly overestimates the compressive stress for specimens with tensile prestrain, while the second approach is able to accurately predict the cyclic plasticity in specimens with tensile and compressive prestrain.

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Initial stiffness and moment resistance of reinforced joint with end-plate connection
Sufang WANG, Yiyi CHEN,
Front. Struct. Civ. Eng.    2009, 3 (4): 345-351.   https://doi.org/10.1007/s11709-009-0054-x
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In beam-to-column joint with bolted end-plate connection, the structural details of column flange reinforced by backing plate and column web panel reinforced by supplementary plate are analyzed. The joint is divided into some basic components, and the initial stiffness of each component is obtained. Especially, the initial stiffness of reinforced components is drawn by theoretical model and finite element analysis. The initial stiffness of reinforced joint can be obtained by assembling the initial stiffness of each component. The design moment resistance of column flange reinforced by backing plate is deduced based on yield line method, and the design moment resistances of other components are deduced based on present codes. The design moment resistance of the reinforced joint is then determined by the minimum of the design moment resistances of all components. By comparison with the results of finite element calculation, it is verified that the method to calculate the initial stiffness of reinforced joint is accurate enough to be used to estimate the rigid behavior of the joint and to make parametric study.
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Theoretical and experimental study on seismic response control on top of Three-Gorges ship lift towers using magnetorheological intelligent isolation system and its key technique
Weilian QU, Jianwei TU
Front Arch Civil Eng Chin    2009, 3 (1): 32-41.   https://doi.org/10.1007/s11709-009-0003-8
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A vertical ship lift under earthquake excitation may suffer from a whipping effect due to the sudden change of building lateral stiffness at the top of the ship lift towers. This paper proposes a roof magnetorheological (MR) intelligent isolation system to prevent the seismic whipping effect on machinery structures. Theoretically, the dynamic models of MR damper and the mechanical model of ship lift was established, the inverse neural network controlling algorithm was proposed and the fundamental semi-active control equation for the Three-Gorges ship lift where the MR intelligent isolation system was installed was deduced. Experimentally, the experimental model of the ship lift was given, the vibrating table experiment of the MR intelligent isolation system controlling the whipping effect was carried out and the results of the inverse neural network control strategy and passive isolation strategy were compared. In practical aspect, the large-scale MR damper (500 kN) and a sliding support with limited stiffness were designed and fabricated. It was proven that the MR intelligent isolation system with proper control strategy can greatly reduce the seismic whipping effect on the top workshop of the ship lift and be simple and effective enough to be applied to real engineering structures.

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