Sep 2009, Volume 3 Issue 3
    

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  • Research articles
    Distribution of background equivalent static wind load on high-rise buildings
    Jianguo ZHANG , Ming GU ,
    2009, 3(3): 241-248. https://doi.org/10.1007/s11709-009-0036-z
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    In this paper, the along-wind and cross-wind fluctuating load distributions along the height of high-rise buildings and their correlations are obtained through simultaneous pressure measurements in a wind tunnel. Some typical methods proposed in some relative literatures, i.e., load-response correlation (LRC), and quasi-mean load (QML) and gust load envelope (GLE) methods, are verified in terms of their accuracy in describing the background equivalent static wind load distribution on high-rise buildings. Based on the results, formulae of the distribution of background equivalent static load on high-rise buildings with typical shapes are put forward. It is shown that these formulae are of high accuracy and practical use.
  • Research articles
    Wind-induced vibration control of Hefei TV tower with fluid viscous damper
    Zhiqiang ZHANG , Aiqun LI , Jianping HE , Jianlei WANG ,
    2009, 3(3): 249-254. https://doi.org/10.1007/s11709-009-0038-x
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    The Hefei TV tower is taken as an analytical case to examine the control method with a fluid viscous damper under wind load fluctuation. Firstly, according to the random vibration theory, the effect of fluctuating wind on the tower can be modeled as a 19-dimensional correlated random process, and the wind-induced vibration analysis of the tower subjected to dynamic wind load was further obtained. On the basis of the others’ works, a bi-model dynamic model is proposed. Finally, a dynamic model is proposed to study the wind-induced vibration control analysis using viscous fluid dampers, and the optimal damping coefficient is obtained regarding the wind-induced response of the upper turret as optimization objectives. Analysis results show that the maximum peak response of the tower under dynamic wind load is far beyond the allowable range of the code. The wind-induced responses and the wind vibration input energy of the tower are decreased greatly by using a fluid viscous damper, and the peak acceleration responses of the upper turret is reduced by 43.4%.
  • Research articles
    Experiment and calculation on seismic behavior of RC composite core walls with concealed steel truss
    Wanlin CAO , Weihua CHANG , Changjun ZHAO , Jianwei ZHANG ,
    2009, 3(3): 255-261. https://doi.org/10.1007/s11709-009-0043-0
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    To improve the seismic performance of reinforced concrete core walls, reinforced concrete composite core walls with concealed steel truss were proposed and systemically investigated. Two 1/6 scale core wall specimens, including a normal reinforced concrete core wall and a reinforced concrete composite core wall with concealed steel truss, were designed. The experimental study on seismic performance under cyclic loading was carried out. The load-carrying capacity, stiffness, ductility, hysteretic behavior and energy dissipation of the core walls were discussed. The test results showed that the seismic performance of core walls is improved greatly by the concealed steel truss. The calculated results were found to agree well with the actual measured ones.
  • Research articles
    Ultimate load analysis of pretensioned inverted T-beams with circular web openings
    Hock Tian CHENG , Bashar S. MOHAMMED , Kamal Nasharuddin MUSTAPHA ,
    2009, 3(3): 262-271. https://doi.org/10.1007/s11709-009-0031-4
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    The provision of transverse openings in floor beams to facilitate the passage of utility pipes and service ducts not only results in a more systematic layout of pipes and ducts, it also translates into substantial economic savings in the construction of a multi-storey building. In this paper, ultimate load analysis of statically loaded simply supported pretensioned inverted T-beams with circular web openings is presented. Major findings relevant to ultimate load analysis of pretensioned beams with circular web openings are summarized. An attempt has been made to answer the frequently asked questions related to ultimate load analysis on multiple circular web openings. It has been shown that the analysis method for pretensioned beams with multiple large circular web openings can be further simplified without sacrificing rationality.
  • Research articles
    Comparisons of bridges flutter derivatives and generalized ones
    Fuyou XU , Zhe ZHANG , Cailiang HUANG , Airong CHEN ,
    2009, 3(3): 272-278. https://doi.org/10.1007/s11709-009-0042-1
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    The causes of the nonlinearity of self-excited aerodynamic force of bridge are interpreted from such two aspects as amplitude and wind velocity. The concept of “generalized flutter derivative” is proposed, and its physical meaning is illustrated. The graphs of the generalized flutter derivatives of plate and Sutong Bridge section model are plotted. The characteristics of all generalized flutter derivatives are compared and analyzed, and their superiorities are verified. The results indicate that the physical meaning of generalized flutter derivatives are more explicit compared to the traditional ones. It is more convenient to understand the nonlinearity properties of self-excited aerodynamic force of bridge according to the generalized flutter derivatives graphs with the wind velocity as the horizontal coordinate.
  • Research articles
    Probabilistic model for vessel-bridge collisions in the Three Gorges Reservoir
    Bo GENG , Hong WANG , Junjie WANG ,
    2009, 3(3): 279-285. https://doi.org/10.1007/s11709-009-0044-z
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    Based on a field observation on vessel transit path of three bridges over the Yangtze River in the Three Gorges Reservoir, and an analysis of the geometric probabilistic model of transiting vessels in collision probability calculation, the aberrancy angle and vessel velocity probabilistic model related with impact force, a probabilistic model is established and also verified by goodness-of-fit test. The vessel transit path distribution can be expressed by the normal distribution model. For the Three Gorges Reservoir, the mean and standard deviation adopt 0.2w and 0.1w, respectively (w is the channel width). The aberrancy angle distribution of vessels accepts maximum I distribution model, and its distribution parameters can be taken as 0.314 and 4.354. The velocity distribution of up-bound and down-bound vessels can also be expressed by the normal distribution model.
  • Research articles
    Limit span of self-anchored cable-stayed suspension cooperation system bridge based on strength
    Zhe ZHANG , Huili WANG , Xiaomeng GE , Sifeng QIN ,
    2009, 3(3): 286-291. https://doi.org/10.1007/s11709-009-0045-y
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    The limit span of self-anchored cable-stayed suspension bridge is deduced. The relations among the geometrical parameters, loads and material characteristics are also analyzed. Based on the material strength and commonly used materials, the limit spans of self-anchored cable-stayed suspension bridges with concrete girder or steel girder under vertical static load are discussed in detail. The corresponding upper limit spans and the effect of the factors on the span are given. The results indicate that increasing rise-span ratio, height-span ratio and cable-stayed segment length or reducing the second dead load could increase the cooperation system span.
  • Research articles
    Experimental study of aerodynamic interference effects on aerostatic coefficients of twin deck bridges
    Zhiwen LIU , Zhengqing CHEN , Gao LIU , Xinpeng SHAO ,
    2009, 3(3): 292-298. https://doi.org/10.1007/s11709-009-0048-8
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    The aerodynamic interference effects on aerostatic coefficients of twin deck bridges with large span were investigated in detail by means of wind tunnel test. The distances between the twin decks and wind attack angles were changed during the wind tunnel test to study the effects on aerodynamic interferences of aerostatic coefficients of twin decks. The research results have shown that the drag coefficients of the leeward deck are much smaller than that of a single leeward deck. The drag coefficients of a windward deck decrease slightly compared with that of a single deck. The lift and torque coefficients of windward and leeward decks are also affected slightly by the aerodynamic interference of twin decks. And the aerodynamic interference effects on lift and torque coefficients of twin decks can be neglected.
  • Research articles
    Centrifuge model test and field measurement analysis for foundation pit with confined water
    Chunlin DING , Xiaohong MENG ,
    2009, 3(3): 299-304. https://doi.org/10.1007/s11709-009-0035-0
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    The similarity law of centrifuge test was developed for the seepage field and stress field of a foundation pit with confined water by analyzing control equations, and a similarity index and a similarity coefficient of centrifuge test were obtained. Based on the deep foundation pit of the Huangxing Road Station of the Shanghai metro line M8, the deformation stability of the pit was tested. Finally, a comparative study was conducted on the test results of the pit deformation and the field measurement results. Comparison results show that the pit deformation regularity of the test is basically identical with that of the field measurement, and the difference in pit deformation between the test and the field measurement is within 50%. The centrifuge model test can effectively simulate the displacement response of the ground and retaining structure during dewatering and excavation for the pit with confined water, which provides a reliable basis for the design and construction of the pit with confined water.
  • Research articles
    A new method of studying collapsibility of loess
    Yuanqing ZHU , Zhenghan CHEN ,
    2009, 3(3): 305-311. https://doi.org/10.1007/s11709-009-0040-3
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    A new triaxial testing system that could control suction in wetting-induced collapsible tests was successfully developed to study the suction effects on wetting-induced collapsible deformation. The pedestal of the triaxial cell was made up of two parts, and the equipment not only could control suction but also could make water accessible to soil. A pressure/volume-controlled equipment was combined with the triaxial system to measure the water volume absorbed by samples accurately and to add pressure on water to filtrate into the sample. The apparatus could measure volume change precisely and keep the deviator stress unvaried, as well as measure the volume of water filtrating into the samples exactly. A triaxial collapsible testing procedure was described using the new apparatus for undisturbed collapsible loess with controlled suction. Furthermore, a series of double triaxial collapsible tests were conducted under different suctions and the same net cell pressure, and tests under different net cell pressures and the same suction were also done. It was indicated that the collapsible deformation increased with the increasing suction, and the effect of the net cell pressure on collapsible deformation was remarkable. The new triaxial apparatus was a useful facility to study the collapsible behavior of loess.
  • Research articles
    Dynamics simulation of bottom high-sediment sea water movement under waves
    Xueyi YOU , Wei LIU , Houpeng XIAO ,
    2009, 3(3): 312-315. https://doi.org/10.1007/s11709-009-0037-y
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    The movement of bottom high-sediment sea water under water waves, especially that of the high-sediment water layer close to the sea bottom, is important to the resuspension and settlement of sediment. Supposing that the high-sediment sea water is a Newtonian fluid, based on Navier-Stokes (N-S) theory, the movement of the interfaces of air-water and water-sediment water was tracked by the volume of fluid (VOF) method. The velocity field of sediment water was simulated by considering the effect of water waves. The results show that the movement of sediment water is very different from that of sea water, which provides a solid basis for understanding the resuspension and settlement of sediment and the formation of bottom stripe, and the VOF method can trace the movement of the two interfaces simultaneously; the movement of the air-water interface has a strong effect on that of the water-sediment water interface, while the effect of the water-sediment water interface movement on the air-water interface is not obvious.
  • Research articles
    Numerical simulation of damage in high arch dam due to earthquake
    Hong ZHONG , Gao LIN , Hongjun LI
    2009, 3(3): 316-322. https://doi.org/10.1007/s11709-009-0039-9
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    Based on the assumption that concrete is macroscopic homogeneous, the cracking evolution process and damage mode of high arch dams are studied in consideration of the heterogeneity of concrete in mesoscale. The bilinear damage evolution model and the damage evolution model expressed in power function with descending section are adopted to combine with the Mohr-Coulomb criterion to investigate the crack development and fracture mode of high arch dams under the action of an earthquake. The analysis result of a high arch dam in China under design shows that cracks that take place in concrete are caused by excessive tensile stress. The cracks initiate at the middle of the dam top and distribute at the upper half of the dam while the rest of the parts remain intact. This conclusion agrees with the model test result.
  • Research articles
    Correlation between tension softening relation and crack extension resistance in concrete
    Xiufang ZHANG , Shilang XU ,
    2009, 3(3): 323-329. https://doi.org/10.1007/s11709-009-0041-2
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    Changes of the material fracture energy consumption with crack propagation can be described by a crack extension resistance curve, one of the fundamental fracture criteria in crack mechanics. Recently, experimental observation of the fracture behavior in concrete was used to develop a new fracture criterion, the crack extension GR resistance curve, to analyze crack propagation during the entire concrete fracture process. The variation of the crack extension resistance is mainly associated with the energy consumption in the fracture process zone ahead of the stress-free crack tip. The crack extension resistance is then a function of the softening curve, which is a basic mechanical property in the fracture process zone. The relationship between the softening curve and the crack extension GR resistance curve is then analyzed based on results of three-point bending beams tests. The results indicate that the characteristic points of the crack extension resistance GR curve is closely related to the characteristic point on used tension softening curve.
  • Research articles
    Calculation of diagonal section and cross-section bending capacity for strengthening RC structure using high-performance ferrocement laminate
    Shouping SHANG , Fangyuan ZHOU , Wei LIU ,
    2009, 3(3): 330-338. https://doi.org/10.1007/s11709-009-0046-x
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    Because there is a great demand of reinforcement and retrofitting of aged structures nationwide, as well as the rapid development of innovative building materials, the adoption of strengthening RC structures using new inorganic materials has become possible. High-performance ferrocement laminate (HPFL) is an effective method of strengthening concrete structure. High-performance ferrocement laminate is a new type of inorganic material with the advantages such as high strength, small contraction, good bonding properties, etc. This paper introduces the formula of cross-section bending capacity for strengthening concrete beams with HPEL. A comparative analysis of experimental data, as well as the calculation of diagonal section bearing capacity of concrete members, is given.
  • Research articles
    Construction technology on pile foundation of No. 6 main pier in Dashengguan Yangtze Bridge
    Hongbin YU , Zeping LIAN ,
    2009, 3(3): 339-343. https://doi.org/10.1007/s11709-009-0047-9
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    Based on pile foundation construction of No. 6 main pier, deep mudstone geological foundation and deep-water construction in Nanjing-Dashengguan Yangtze Bridge, the method of super-large-diameter bored pile in deep water is studied. The spread drill, application of PHP mud, and choice of machine are solved by adopting two machines of KTY4000 and KPG300A. Besides, the airlift reversing circulation is selected in slag discharge. The results show that this method can ensure successfully the construction of pier foundation to satisfy the demands of codes.