Shanghai Municipal Engineering Design Institute Group Co.
Shanghai Municipal Engineering Design Institute Group Co.
Huang M.,Shanghai Municipal Engineering Design Institute Group Co. |
Wen X.,Shanghai Municipal Engineering Design Institute Group Co. |
Wang L.,Virginia Polytechnic Institute and State University
Construction and Building Materials | Year: 2017
Epoxy asphalt is provided with excellent performance. However, its construction time is too short for the current situation in China, which therefore has brought about the issues with harsh conditions, high costs and risks. In order to solve this problem, this paper proposes a new foamed epoxy asphalt (FEA), and adopts a new curing system. To investigate the hardening system effect on foamed epoxy asphalt, 3 key points in FEA research have been proposed, namely foaming effect, influence of waiting time for compacting during construction, and strength grows in health preserving. Conventional Marshall method is used for the preparation of the testing specimens. The results obtained showed that the optimum foaming temperature is 120 °C, with the optimum water consumption being 2% relatively; the minimum compacting temperature of FEA mixt is 56 °C, and its longest waiting time for compacting is 6 h. At least 50 days of health preserving time is recommended after the completion of the construction of the FEA paving, which equals to 24 h at a constant temperature of 60 °C preserving for the future laboratory study due to the time-temperature equivalence rule. © 2017 Elsevier Ltd
Shen Y.,Shanghai Municipal Engineering Design Institute Group Co.
Modern Tunnelling Technology | Year: 2016
As one of the main disasters threatening the safe operation of tunnels, fire can seriously damage or destroy tunnel lining structures. Spalling of a shield tunnel lining may occur due to fire, and the lining is prone to abrupt failure at the joints between segments. Meanwhile, the risk of collapse of tunnel lining structures due to fire is extremely high, thanks to low restraint of the ground around the shield tunnel. Through numerical calculations, we study the temperature characteristics and mechanical behaviors of shield tunnel lining structures under different heating curves and ground elastic restraints-including the temperature field, deformation and internal force distribution of the lining structure system and explore the effects of key factors like buried depth, spalling, staggered erection and segment layout variation on the compound structural system. © 2016, Editorial Office of "Modern Tunnelling Technology". All right reserved.
Li G.-P.,Tongji University |
Li J.-X.,Shanghai Municipal Engineering Design Institute Group Co.
Zhongguo Gonglu Xuebao/China Journal of Highway and Transport | Year: 2017
In order to improve the complex operation procedures of which the parallel steel strand stay cables of bridges need multiple times tension by taking the tensile cable force to control tension, and reduce the accumulative errors during the process, meanwhile make the forces of the steel strand stay cables be well distributed after the tension. Non-stress length of stay cables, was calculated and chosen to control tension, and construction scheme by the method of once tensioning for every strand was designed, elaborated and optimized. The equation of the stay cable was derived by considering the geometric nonlinearity of the steel strand and the non-stress length controlling tension under target cable forces was obtained. The deviation between designed target cable forces and forces in actual construction phases was amended by using binding method of hierarchical local optimization, considering artificial errors or deformation of the suspended tower and the girder, adopting the obtained non-stress length to control the tension of the stay cable in actual construction phase. The non-stress length of the steel strand conformed with actual operation can be obtained to achieve the aim of once tensioning and equal pulling force of every steel strand after tension, and more precise cable force of bridges. In the end, a simulation example of actual working conditions was provided to verify the construction scheme. The results show that the given target forces can be finished by once tensioning adopting non-stress length to control the tension scheme. Considering the small deviation between non-stress length of controlling tension after the optimization of artificial errors and non-stress length in actual working conditions, the corresponding error of the tensile cable force decreases to 0.72% after the further optimization. The forces of the steel strand stay cables are equal after the tension, which meets the requirements of construction. The relevant firmware embedded intelligent jack after curing can be used in construction of the steel strand stay cables. © 2017, Editorial Department of China Journal of Highway and Transport. All right reserved.
Yi T.-H.,Dalian University of Technology |
Li H.-N.,Dalian University of Technology |
Zhao X.-Y.,Shanghai Municipal Engineering Design Institute group Co.
Sensors (Switzerland) | Year: 2012
In structural vibration tests, one of the main factors which disturb the reliability and accuracy of the results are the noise signals encountered. To overcome this deficiency, this paper presents a discrete wavelet transform (DWT) approach to denoise the measured signals. The denoising performance of DWT is discussed by several processing parameters, including the type of wavelet, decomposition level, thresholding method, and threshold selection rules. To overcome the disadvantages of the traditional hard- and soft-thresholding methods, an improved thresholding technique called the sigmoid function-based thresholding scheme is presented. The procedure is validated by using four benchmarks signals with three degrees of degradation as well as a real measured signal obtained from a three-story reinforced concrete scale model shaking table experiment. The performance of the proposed method is evaluated by computing the signal-to-noise ratio (SNR) and the root-mean-square error (RMSE) after denoising. Results reveal that the proposed method offers superior performance than the traditional methods no matter whether the signals have heavy or light noises embedded. © 2012 by the authors; licensee MDPI, Basel, Switzerland.
Li F.-D.,Shanghai Municipal Engineering Design Institute Group Co.
Bridge Construction | Year: 2016
To study the characteristics of the separated and obliquely set steel anchor boxes in pylon of cable-stayed bridge, the structural characteristics of the anchor boxes and the force conditions of the anchorage zone in the pylon were analyzed. Because the anchor boxes were separated and obliquely set, the transverse horizontal component force could not be self-balanced and in comparison to the rigidity of the anchor boxes, the rigidity of the concrete pylon columns increased and at the same time, the pylon columns bore the whole of the transverse horizontal force and much of the longitudinal horizontal force. By way of example of the diamond-shape pylon of a single-pylon cable-stayed bridge, the software ANSYS was used to establish the spatial finite element model for the anchor boxes in the pylon, the influences of the obliquely setting of the anchor boxes on the stress distribution of the anchor boxes and pylon walls as well as the ratios of the horizontal force distribution of the stay cables between the anchor boxes and pylon walls were analyzed. The results of the analysis show that as compared to the integral steel anchor box, the ratios of the horizontal force distribution of the stay cables of the separated and obliquely set steel anchor boxes decrease and the pylon columns bear much of the horizontal component force. The force conditions of the components and shear studs of the anchor boxes are not symmetric, the stress levels are low and are not uniform. © 2016, Wuhan Bridge Research Institute. All right reserved.
Wang H.,Shanghai Municipal Engineering Design Institute Group Co.
Yantu Lixue/Rock and Soil Mechanics | Year: 2012
Using numerical simulation by PFC 2D (particle flow code in two dimensions), the group piles effect of pile tip resistance of under-reamed piles on uplift loading is studied. The increase of tip resistance with uplift displacement and the variations of soil displacement around pile tip are observed in the simulation. The differences between single pile (pier) and group piles (piers) in uplift loading are shown and the development of tip resistance with uplift displacement for group piers in different spaces is compared. It is shown that the uplift characteristics are similar for single pile (pier) and group piles (piers) when the normalized uplift displacement s/D is smaller than 0.1. With the development of uplift displacement, the tip resistance of single pile (pier) is larger than that in group piles (piers) and the interaction of soil particles around tip emerges. When the normalized uplift displacement s/D is smaller than 0.5, the tip resistance of central pile (pier) is larger than that of side pile (pier) in the group piles (piers). When the normalized uplift displacement s/D is larger than 0.5, the tip resistance of side pile is larger than that of center pile in the group piles and that is reverse in the group piers, which embodied the effects of side restriction of pile shaft on the mobilization of tip resistance. The characteristics of group piers had obvious difference with single pier only in larger displacement with the increase of pier distance.
Bai J.,Shanghai Municipal Engineering Design Institute Group Co.
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2015
Besides the static loading of the workshop and crane beams, the cyclic loading brought about by the crane operation was applied to the pile foundation of a heavy lifting workshop. The cyclic loading has two characteristics. One is the high proportion of the cyclic loading to the total, and the other is its rather high frequency. In this study, the operation of the crane in a lifting workshop of a shipbuilding base in Shanghai was recorded and analyzed through artificial records. A statistical method suitable for analysing the crane operation rules of the shipbuilding base was established. Besides, the triangular wave was assured to be suitable for fitting the cyclic loading waveform for the crane. Furthermore, a simplified analytical method was established based on the normative crane working system level. The calculation results validate the reliability of the measured data. ©, 2015, Chinese Vibration Engineering Society. All right reserved.
Li Y.,Shanghai Municipal Engineering Design Institute Group Co.
Zhongguo Gonglu Xuebao/China Journal of Highway and Transport | Year: 2015
In order to further analyze the proper design parameters for cable clips of suspension bridges with carbon fiber reinforced polymer (CFRP) cables, the Tsai-Hill failure criterion of composite material was firstly introduced, and the formulas for cable moment at the clips was derived through analysis method, based on which calculation method for the clip design of CFRP suspension bridges was proposed. Then, parametric analysis on the mechanical indexes of clips on the CFRP cable was conducted, where the influences of diameter of cable wire, interval between clips, length of clips, tension of bolts, interval between bolts, friction factor between CFRP and steel, and friction factor of CFRP on force performance of cable clip were investigated. The results show that the mechanics behavior of clips can be improved significantly by reducing the cable wire diameter, increasing the clip length, increasing the tension of bolts, reducing the interval between bolts, and enhancing the friction factor between CFRP and steel. The interval between clips should be chosen within a reasonable range, otherwise negative effects could be brought about. ©, 2015, Xi'an Highway University. All right reserved.
Li Y.,Shanghai Municipal Engineering Design Institute Group Co.
Chongqing Daxue Xuebao/Journal of Chongqing University | Year: 2012
This paper proposes an analysis method for the static mechanics of suspension bridges based on segmental catenary and FEM software. A comparative research on mechanics of suspension bridge with a span of 2000~5000 m is conducted according to the proposed method, and CFRP suspension bridges are proved advantageous and practicable. A parametric study for the deflection performance of 2000 m CFRP suspension bridge is executed in order to enhance its stiffness, where the span arrangement, rise to span ratio, side to main span ratio, inertia of girder and tower, and the central buckle are considered, respectively. A serials of design suggestions for improving the structural stiffness are proposed.
Lin F.,Shanghai Municipal Engineering Design Institute Group Co.
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2014
The increase of embedded depth of retaining wall, reinforcement of foundation soil and set-up of partition wall between foundation pits and buildings are widely-used techniques to protect the surrounding facilities. The problems of budget and construction period can be possibly reduced by optimization design. Currently, the optimization design of the foundation pits focuses mainly on types of retaining wall and structural members and not on the whole retaining system. Based on a deep foundation pit close to a metro station in operation and a large-diameter water pipe, a 3D finite element model is proposed. The behaviors of soils are assumed to conform to Drucker-Prager model, and three different construction sequences are simulated. Considering the distinct stress states of soils during construction, loading and unloading modulis of each soil type are adopted. The results show that the implementation of the temporary partition wall can be canceled, and the basement floor No.1 and No.2 can be excavated downward simultaneously. The design of retaining system is optimized, and the settlement-sensitive municipal facilities are safe.