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Improved methods for decreasing stresses of concrete slab of large-span through tied-arch composite bridge

Journal of Central South University 2010年第3期17卷 648-652页

作者：周德叶梅新罗如登 School of Civil Engineering and Architecture Central South University

Mechanical behavior of concrete slab of large-span through tied-arch composite bridge was investigated by finite element analysis (FEA). Improved methods to decrease concrete stresses were discussed based on comparisons of different deck schemes, construction sequences and measures, and ratios of reinforcement. The results show that the mechanical behavior of concrete slab gets worse with the increase of composite regions between steel beams and concrete slab. The deck scheme with the minimum composite region is recommended on condition that both strength and stiffness of the bridge meet design demands under service loads. Adopting in-situ-place construction method, concrete is suggested to be cast after removing the full-supported frameworks under the bridge. Thus, the axial tensile force of concrete slab caused by the first stage dead load is eliminated. Preloading the bridge before concrete casting and removing the load after the concrete reaching its design strength, the stresses of concrete slab caused by the second stage dead load and live load are further reduced or even eliminated. At last, with a high ratio of reinforcement more than 3%, the concrete stresses decrease obviously.

关键词： composite bridge concrete slab tension through tied-arch large span finite element method

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Influence of Heat Exchange Coefficients on Both Optimized Thermal Contact (OTCR) and Critical (CTCR) Resistances at the Contact Interface of a Flat concrete slab and a Rice Straw Board

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Energy and Power Engineering 2021年第12期13卷 392-402页

作者： Alassane Diene Mamadou Lamine Lo Abdoulaye Sene Ablaye Fame Youssou Traore Seydou Faye Issa Diagne Mamadou Babacar Ndiaye Gregoire Sissoko Polytechnic School of Thiès Thiès Senegal Laboratory of Semiconductors and Solar Energy Physics Department Faculty of Science and Technology University Cheikh Anta Diop Dakar Senegal University Institute of Technology University Iba Der THIAM of Thiès Thiès Sénégal Groupe International de Recherche en Energie Renouvelable Dakar Senegal

The study is carried out in imperfect contact with a concrete slab wall attached to a panel based on rice straw compressed in a dynamic frequency regime. We will propose the characterization of thermal insulation for thermal resistance of contact (x = 0.05 m). The impact of heat exchange coefficients on the front face (x = 0 m) and the rear face (x = 0.1 m) on these resistors is shown.

关键词： concrete slab Rice Straw Board Thermal Resistance of Contact Frequency Dynamic

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Acoustic Emission Properties of concrete slab During Fatigue Testing with a Running-Wheel Load

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Journal of Civil Engineering and Architecture 2017年第3期11卷 213-221页

作者： Mitsuharu Shiwa Zhengwang Li Takuya Maeshima Yasuhiro Koda Yasushi Tanaka National Institute for Materials Science Tsukuba Ibaraki 305-0047 Japan Nippon Physical Acoustics Ltd. Tokyo 150-0011 Japan Department of Civil Engineering College of Engineering Nihon University Koriyama Fukushima 963-1165 Japan Institute of Industrial Science The University of Tokyo Tokyo 153-8505 Japan

AE （acoustic emission） signals from concrete slab during fatigue testing with a running-wheel load were evaluated. The signals were recorded by remote sensors connected to a computer network. The sensing equipment consisted of 60 kHz resonant-type AE sensors mounted on a reinforcing steel bar as a waveguide, together with a 16-channel sensor highway AE system. Because the detected AE signals included periodic mechanical noise from the motion of the wheel, these noises were eliminated by means of signal processing. The AE waveguide measurement over a length of 3 m detected fractures as vertical and horizontal cracks in the RC （reinforced concrete） slab. Those cracks were analyzed by correlating AE parameters with macroscopic distortions and the numbers of fatigue cycles. In the AE events and AE energy, two types of AE phenomena, active region and inactive region, were observed during fatigue testing. The vertical cracks were characterized by an AE amplitude of 58 dB, a peak frequency of 30 kHz, and a ratio of the rise time to the maximum amplitude value （RA） of 100. The horizontal cracks were characterized by an AE amplitude of 85 dB, a peak frequency of 60 kHz, and an RA value of 10.

关键词： Acoustic emission concrete slab waveguide fatigue testing running-wheel load.

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Numerical Analysis of Effect of Water on Explosive Wave Propagation in Tunnels and Surrounding Rock

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Journal of China University of Mining and Technology 2007年第3期17卷 368-371页

作者： XIA Chang-jing SONG Zhen-duo TIAN Lu-lu LIU Hong-bin WANG Lu WU Xiao-fang School of Mechanics ＆ Civil Engineering China University of Mining ＆ Technology Beijing 100083 China

Based on the application of practical engineering,propagation processes of explosive waves in rock with water well and tunnel are simulated by ANSYS/LS-DYNA software. The evolution of damage in rock is presented. The effect of water on the damage of the concrete slab in a tunnel is compared with damage inflicted without water. The numerical simulation illustrates that water plays an important role in the evolution of damage of the concrete slab in a mine tunnel. In the presence of water in the rock the concrete slab is damaged more severely than without water in rock. The effect of water location in the rock is also considered. It is found that the concrete slab in the tunnel shows various degrees of damage as a function of the different locations of water. Attenuation laws of stress waves over time-space in rock with water are also obtained. Numerical results indicate that,under blast loading,there are three zones in the rock: a crushed zone nearby the explosive charge,a damaged zone and an elastic zone. The conclusions of numerical analysis may provide references for blasting designs and structure protection.

关键词： explosive wave numerical simulation concrete slab damage evolution

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