Flexural ductility and deformability of concrete beams incorporating high‐performance materials

High‐performance materials, such as high‐strength concrete (HSC) and high‐strength steel (HSS), are often adopted in tall buildings to reduce member size and save space. The use of HSC and/or HSS can significantly increase the flexural strength of concrete members but may also adversely affect the flexural ductility and deformability. Herein, the pros and cons of using HSC and HSS in concrete beams are investigated in terms of the limits of flexural strength, ductility and deformability that can be simultaneously achieved using nonlinear moment‐curvature analysis with stress‐path dependence of the reinforcement taken into account. The results reveal that the use of HSC or both HSC and HSS in concrete beams can at the same strength increase the ductility and deformability, or increase the strength without depleting the ductility and deformability. However, the use of HSS has no such benefit, albeit it can reduce the steel area required. Copyright © 2010 John Wiley & Sons, Ltd.     

Design and behaviour of a reinforced concrete high‐rise tube building with belt walls

This paper discusses modelling, analysis and design issues for a 55‐storey hotel building recently planned for New York City, USA. The lateral force resistance of the investigated building primarily makes use of exterior reinforced concrete shear walls in one direction and exterior reinforced concrete moment frames in the other direction, in which tube action credited to the connection of the walls and frames was designed to play a significant role in the lateral stiffness and strength. In addition, a full‐storey belt wall system, enclosing the entire perimeter of the building at approximately the mid‐height, is expected to provide a considerable contribution to the lateral force resistance. In this paper, the contribution of tube action and the belt wall system to structural behaviour is investigated in terms of quantitative measures such as lateral drift, building dynamic properties and flange frame contribution to overturning moment resistance. In addition, axial force distribution among the various vertical members under lateral forces is discussed for each of the two principal building directions. Finally, the seismic behaviour of the investigated building is qualitatively discussed in order to propose a seismic force‐resisting system classification into which this concrete tube system would fit. Copyright © 2010 John Wiley & Sons, Ltd.     

A generalized method for estimating drifts and drift components of tall buildings under lateral loading

A generalized method for estimating the drifts of tall buildings composed of planar moment‐resisting frames and coupled shear walls under lateral loading is presented. This method establishes the stiffness equations at the story levels by assuming that all the nodes in the same floor of a planar lateral‐force‐resisting unit have an identical lateral displacement, an identical rotation component due to the axial deformations of the columns, and an identical rotation component due to the flexural and shear deformations of the beams. By adopting this simplification, the story drifts contributed by different types of deformations, namely, the axial deformations of the columns or wall piers, the flexural and shear deformations of the beams, and the double‐curvature bending and shear deformations of the columns or wall piers, can be identified. In the formulation of the stiffness matrix, the P‐Delta effects were also incorporated. Through comparisons between the lateral displacements and story drifts computed using the proposed method and those computed using the structural analysis software Midas/Gen, the proposed method is proved to have high accuracy in estimating the drifts of tall building structures.     

Application of Taguchi method for the optimization of Fe2+ removal from contaminated synthetic groundwater using a rotating packed bed contactor

Malaysia contains elevated levels of iron in shallow groundwater in the range of 3–7 mg Fe/L compared to the USEPA safe limit of 0.3 mg Fe/L. Air Kelantan Sdn Bhd in Malaysia uses the ‘River Bank Filtration’ (RBF) technology to harvest hyporheic water. The RBF treatment removes the turbidity of the river water through the river bed acting as a filter, but is unable to remove the Fe from the harvested water. This work proposes a technology to reduce Fe concentration in the extracted water using granular activated carbon in a laboratory‐scale rotating packed bed contactor (RPBC). The Taguchi method was used for optimizing the operating conditions for the adsorption of Fe onto activated carbon in the RPBC system. Taguchi optimization results showed that a removal efficiency of 87% Fe from a 50 mg Fe/L concentration could be achieved by a RPBC at an initial pH of 6.5, a feed rate of 40 L/h, a rotating speed of 1600 rpm and a packing density of 357 kg/m³.     

Use of pile foundations in soils classed as type II in terms of proneness to slump-type settlement and compacted with wetting

Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 5, pp. 12–15, September–October, 1989.     

液化天然气架空管道受力分析及设计方法

液化天然气架空管道的设计工作是液化天然气供应站总体设计中不可或缺的一个组成部分,而相当一部分城市燃气行业的设计人员对这种架空低温介质管道的设计工作比较陌生.在此种管道的设计工作中,管道的受力分析(特别是温度应力分析)是设计工作能否成功的一个重要因素.本文将结合自身的设计经验对液化天然气架空管道的受力机理、分析方法和设计中应注意的问题进行阐述,以期对读者能有所帮助.     

铜铝复合柱翼型散热器散热量拟合公式的研究

对不同规格型号的铜铝复合柱翼型散热器进行了实验研究,确定影响散热器散热量铝翼管的定型尺寸,拟合出散热量与定型尺寸的函数关系式。并运用此拟合函数关系式,分别计算出实验所用的铜铝复合柱翼型散热器在标准工况下的散热量,将此散热量与实验所测的散热量进行比较,得出两者数值偏差均在±10%以内。从而为在工程设计中铜铝复合柱翼型散热器的选用与配置,提供了理论依据。     

高应变动力测试技术与静载测试技术的对比

通过对大量的桩基静载荷试验和同一根桩上高应变的对比研究，总结了高应变测试极限承载力的准确性与可靠性。分析了引起高应变测试结果误差的原因，提出了消除高应变测试误差的一些方法和注意事项。     

聚乙烯(PE)管应用于定向钻的探讨

PE管在燃气管网中的应用日趋广泛,目前正在尝试性地应用于定向钻穿越.文章就其允许的曲率半径、穿越长度、防腐及回拖时所受的拉伸应力等进行了讨论与比较.