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Zhengzhou, China

Chen W.,University of Sichuan | Zhang J.-W.,Design Institute Company Ltd | Peng H.,University of Sichuan
Electronic Journal of Geotechnical Engineering | Year: 2014

The creep laws and creep mechanism of rockfill materials are important problems of interest in practice. Constant-stress drained creep tests were conducted on sandstone rockfill materials by a large-scale stress-controlling triaxial apparatus. The sandstone rockfill materials have a self-similar fractal structure in mass. The tests were conducted under different stress levels. The particle breakage degrees of these rockfill materials were measured by sieving. The rockfill materials manifest instantaneous and creep strain. The axial and volumetric creep strains increase with increasing stress levels. The strain-time relationship can be described with a power function. The stress-axial strain and stress-volumetric strain behavior can be expressed by hyperbolic and linear functions, respectively. Particle breakage degrees also increase with the increase in stress levels. The relative particle breakage index was adopted to describe the particle breakage of the rockfill materials. The axial and volumetric creep strains are linearly dependent on the relative particle breakage index. Particle breakage is one of the creep mechanisms of rockfill materials. © 2014 ejge. Source

Wang Y.,Design Institute Company Ltd | Wang Z.,Chengdu University of Technology | Wei X.,Chengdu University of Technology | Qiang S.,Chengdu University of Technology
Stahlbau | Year: 2013

Gusset plate anchorage devices are widely used in long-span cable-stayed bridges with steel girders because the force in the cable can be transferred directly to the main girder via the gusset plate, which is very convenient for inspection and maintenance. The disadvantage is the severe stress concentration between gusset plate and steel tube, and the cruciform joint between gusset plate, top flange and web of main girder. This paper presents the static analysis of and experimental research into a gusset plate anchorage device. The magnitude and stress distribution of each load case were analysed very carefully, and the stress history of typical points was also monitored to indicate the structural behaviour. Under the load of the maximum design cable force, the anchorage device exhibits linear elastic behaviour on the whole. The von Mises stress at some monitored points reaches the yield stress when the load is 1.28 times the maximum design cable force. Ultrasonic inspection of the test model revealed no strength cracking or plate buckling, which indicates that the safety margin of the anchorage device is sufficient and complies with the requirements of bridge design code. By comparing calculations and test results it could be proved that FEM can be utilized for the structural analysis of gusset plate anchorage devices and that the calculation accuracy exceeds 70 % for most monitored points. Source

Gao Z.,Design Institute Company Ltd
Stahlbau | Year: 2012

Zhengzhou Yellow River road-cum-railway bridge accommodates both the Beijing-Guangzhou passenger railway line and the Zhengzhou-Xinxiang inter-city highway, which cross the Yellow River at Zhengzhou, China (Fig. 1). The bridge is 9177 m long and has two distinct sections[1]: the first is a six-pylon continuous steel-concrete composite truss extradosed bridge with a span arrangement of 120 + 5 × 168 + 120 m; the second is a continuous steel-concrete composite truss with a span arrangement of 5 × 120 m. The main bridge has a double deck, with a six-lane carriageway on the upper deck and a twintrack railway on the lower deck. An inclined truss structure is used for the main bridge superstructure. The upper deck is of concrete, the lower deck uses orthotropic steel solution. The analysis revealed that the main bridge has good rigidity and favourable service conditions for high-speed trains. The main steel truss was constructed by incremental launching. © Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG, Berlin. Source

Gao Z.,Design Institute Company Ltd
Bridge Maintenance, Safety, Management and Life-Cycle Optimization - Proceedings of the 5th International Conference on Bridge Maintenance, Safety and Management | Year: 2010

Major steel bridges for high speed railway in China are recently developed, Some of these bridges, located Beijng-Shanghai and Beijing-Guangzhou High Speed Railways, across Yangtze River and Yellow River, are under construction, include: Tianxingzhou Bridge, Dashenguan Bridge, Zhengzhou Yellow River Bridge, and Jinan Yellow River Bridge. All these major bridges are multy railway lines or rail-cumroad bridges, with heavy loading capacity and high railway operation speeds, therefore, the steel truss structure are adopted for all of them. Some new materials, new structures and new workmanships are applied accordingly. © 2010 Taylor & Francis Group, London. Source

Tan Y.,Tongji University | Wang D.,Design Institute Company Ltd
Journal of Geotechnical and Geoenvironmental Engineering | Year: 2013

Because of its large size (30,000m2 in plan), the 17.85- to 25.89-m-deep foundation pit of the 492-m-high Shanghai World Finance Center building was excavated by the central-island technique, i.e., bottom-up construction of the central cylindrical shaft first and then topdown construction of the peripheral rectangular pit. As part of the comprehensive study on the characteristics of this large-scale foundation pit, this study mainly focuses on the behaviors of the peripheral pit via the following investigated items: (1) lateral wall deflections; (2) vertical wall movements; (3) lateral ground movements; (4) axial forces in the cast floor slabs and braced struts; (5) lateral earth pressures on both sides of retaining walls; (6) variation of pore pressures along depth and deep artesian water levels; (7) ground settlements; (8) subsurface settlements; (9) basal heaves; (10) vertical column movements; and (11) column stresses. To explore the potential effects of pit sizes on the excavation behaviors, field data from another 33 top-down excavations in Shanghai were also included for comparison. The comprehensive comparisons show that in addition to the well-known factors (e.g., excavation depths, supporting system stiffness, and factor of safety against basal heave), pit sizes in plan played a key role in determination of the pit behaviors. The large-scale pits with the areas in plan of 30,000e50,000m2 experienced wall deflections and ground settlements three to five times those of regular building basement and metro station excavations with the sizes in plan no more than 6,000m2, and the corresponding influence zones behind the large-sized pits were also much wider. Different from the braced struts that just carried the load because of soil removal in the proximity, the floor slabs sustained the load induced by exposure of the entire retaining wall along the depth. For the top-down excavations in Shanghai soft clay, the lateral earth pressure envelopes behind the retaining walls were trapezoidal, but their magnitudes were significantly smaller than those predicted by the methods available in the literature, and the corresponding peak values occurred at a greater depth. The influence zones of basal heave caused by soil removal (stress relief) extended much deeper below the excavation bases than those assumed in the conventional slip circle basal stability models. © 2013 American Society of Civil Engineers. Source

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