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Cai H.-B.,University of Science and Technology Beijing | Cai H.-B.,Central Research Institute of Building and Construction Co. | Wu S.-C.,University of Science and Technology Beijing | Zhou Y.,University of Science and Technology Beijing
Yantu Lixue/Rock and Soil Mechanics | Year: 2011

Taking a foundation pit in Beijing as the background, the fast Lagrangian analysis of continua in 3 dimensions (FLAC3D) numerical calculation program and Mohr-Coulomb constitutive model are adopted to make analysis of the deformation and force condition of pile-anchor supporting system on the case of deepening excavation of the existing foundation pit. Calculation results show that the deepening excavation will induce poor bending performance of pile, larger horizontal displacement of supporting structure and failure of anchor system based on the existing supporting scheme. In order to ensure stability of the foundation pit, increasing pile fulcrum is necessary. Several reinforcement schemes are compared on the basis of design change and construction condition. The scheme of increasing anchor cable is adopted to reinforce the foundation pit. The mechanical behavior of foundation pit after deepening excavation with above supporting scheme is analyzed by using numerical simulation. The calculated deformation of foundation pit and supporting system is compared with field monitoring data; and the result shows that the scheme is reasonable. So the research results are of significance as a reference for similar engineering.

Wang J.,Tianjin Chengjian University | Wang J.,Tianjin Key Laboratory of Civil Structure Protection and Reinforcement | Lu P.,Central Research Institute of Building and Construction Co. | Bi J.H.,Tianjin University | And 2 more authors.
Journal of Fluids and Structures | Year: 2016

Cables of cable-stayed bridges may vibrate with large amplitude under wind and rain, which is known as rain-wind induced vibration (RWIV). According to the pervious researches, the formations and oscillations of rivulets on stay cable surface play important roles in RWIV. In this paper, four different 2D models are presented based on lubrication theory, and the best way of simulating RWIV through lubrication theory is confirmed by the comparisons of rivulet motions and cable vibration responses between these four models and pervious researches. On this basis, the relations among rivulet motions, cable aerodynamic forces and vibration responses are investigated to reveal the mechanism of RWIV. Numerical simulation results show that when RWIV occurs, the periodic oscillations of rivulets around cable lead to the periodic fluctuations of cable lift and drag, whose frequencies are almost equal and close to cable natural frequency. Under the periodically fluctuant lift and drag, cable vibrates with large amplitude in across-wind and along-wind directions, which may further enhance the circumferential oscillations of rivulets conversely. These confirm the conclusion that the resonance between rivulets and cable oscillation may be one of the main reasons for RWIV. © 2016 Elsevier Ltd.

Qiu G.-B.,University of Science and Technology Beijing | Yue C.-S.,Central Research Institute of Building and Construction Co. | Li X.,University of Science and Technology Beijing | Guo M.,University of Science and Technology Beijing | Zhang M.,University of Science and Technology Beijing
International Journal of Minerals, Metallurgy and Materials | Year: 2014

Regenerated MgO-CaO brick samples containing 80wt%, 70wt%, and 60wt% MgO were prepared using spent MgO-CaO bricks and fused magnesia as raw materials and paraffin as a binder. The bricks were sintered at 1873 K for 2 h under an air atmosphere and under an isolating system. The microstructure, mechanical properties at room temperature, and hydration resistance of the regenerated samples were measured and compared. The results indicated that the isolating sintering generated a strongly reducing atmosphere as a result of the incomplete combustion of paraffin, and the partial oxygen pressure was approximately 6.68 × 10−7Pa. The properties of the regenerated bricks sintered under air conditions were all higher than those of the bricks sintered under a reducing atmosphere. The deterioration of the bricks was a result of MgO reduction and a decrease in the amount of liquid phase formed during sintering under a reducing atmosphere. © 2014, University of Science and Technology Beijing and Springer-Verlag Berlin Heidelberg.

Han B.,Beijing Jiaotong University | Xie H.-B.,Beijing Jiaotong University | Zhang D.-J.,Central Research Institute of Building and Construction Co. | Ma X.,Beijing Jiaotong University
Materials and Structures/Materiaux et Constructions | Year: 2015

Correlations between the parameters involved in creep models are relatively complex, resulting in difficulties to identify the contribution of each parameter on the predicted creep and reduce creep uncertainty. Sensitivity analysis is a method to quantify the contribution of those parameters. Based on six creep models, B3, B4, ACI-209, MC90, fib MC 2010 and GL2000, the sensitivity of eight parameters, water cement ratio w/c, aggregate cement ratio a/c, cement content c, 28-day compressive strength fcm, 28-day elasticity modulus E28, effective thickness of specimen D, temperature T, and relative humidity H, to the models was analyzed. An updated creep database, NU database, was used to obtain the statistical characters and correlation matrix of the parameters. For these six creep models, direct and indirect path coefficients of each parameter were calculated by using Path Analysis and the path diagrams of the six creep models were obtained. It can be found that there are still some issues in the existing creep models, that coupling relation between the parameters has not been paid enough attentions. Furthermore, concerning the nonlinear relation between parameters, sensitivity of the creep to the parameters were decomposed into correlated and uncorrelated parts by using back propagation artificial neural network. The sensitivity of the six models to each parameter differs from each other, and the basic parameters are identified in the six models by using path analysis and sensitivity analysis. © 2015 RILEM

Hao T.Y.,Central Research Institute of Building and Construction Co. | Wu Z.G.,Central Research Institute of Building and Construction Co. | Bai Y.,University College London | Basheer P.A.M.,Queens University of Belfast
Applied Mechanics and Materials | Year: 2013

By comparing the permeability test results between the autoclam method introduced by Queen's University Belfast and the seepage method specified in China standard, it was found that water permeability index given by autoclam test had a better correlation with seepage value than air permeability index and water absorption index. © (2013) Trans Tech Publications, Switzerland.

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