Evaluation of seismic displacements of quay walls

A new simplified dynamic analysis method is proposed to predict the seismic sliding displacement of quay walls by considering the variation of wall thrust, which is influenced by the excess pore pressure developed in backfill during earthquakes. The method uses the Newmark sliding block concept and the variable yield acceleration, which varies according to the wall thrust, to calculate the quay wall displacement.A series of 1 g shaking table tests were executed to verify the applicability of the proposed method, and a parametric study was performed. The shaking table tests verified that the proposed method properly predicts the wall displacement, and the parametric study showed that the evaluation of a realistic wall displacement is as important as the analysis of liquefaction potential for judging the stability of quay walls.     

Seismic demand sensitivity of reinforced concrete shear‐wall building using FOSM method

The uncertainty in the seismic demand of a structure (referred to as the engineering demand parameter, EDP) needs to be properly characterized in performance‐based earthquake engineering. Uncertainties in the ground motion and in structural properties are responsible for EDP uncertainty. In this study, sensitivity of EDPs to major uncertain variables is investigated using the first‐order second‐moment method for a case study building. This method is shown to be simple and efficient for estimating the sensitivity of seismic demand. The EDP uncertainty induced by each uncertain variable is used to determine which variables are most significant. Results show that the uncertainties in ground motion are more significant for global EDPs, namely peak roof acceleration and displacement, and maximum inter‐storey drift ratio, than those in structural properties. Uncertainty in the intensity measure (IM) of ground motion is the dominant variable for uncertainties in local EDPs such as the curvature demand at critical cross‐sections. Conditional sensitivity of global and local EDPs given IM is also estimated. It is observed that the combined effect of uncertainties in structural properties is more significant than uncertainty in ground motion profile at lower IM levels, while the opposite is true at higher IM levels. Copyright © 2005 John Wiley & Sons, Ltd.     

A TEM and RUM study of the inherent displacive flexibility of the fresnoite framework structure type

 A careful electron diffraction study has been made of the incommensurately modulated room-temperature phases of the fresnoites Ba₂TiGe₂O₈ (BTG) and Ba₂TiSi₂O₈ (BTS) and used to determine their (3+1)- and (3+2)-dimensional superspace group symmetries. The primitive primary modulation wave vectors in both materials are found to occur close to the same position in the parent Brillouin zone, near ∼0.3〈110〉 _p ^*+1/2c _p ^st . A rigid unit mode (RUM) analysis of the inherent displacive structural flexibility of the ideal fresnoite framework structure type is then carried out in an attempt to understand the significance of this particular modulation wave vector. Six zero-frequency RUM modes and two close to zero frequency quasi-RUM (Q-RUM) modes are found to exist for any modulation wave vector. These RUM modes are all primarily associated with rotations of the constituent TO₄ (T=Si or Ge) tetrahedra and TiO₅ square pyramids around in-plane i.e. perpendicular to c rotation axes. A seventh RUM mode involving rotation of the constituent rigid polyhedra around c combined with shifts in the basal plane is found but only at a very specific modulation wave vector q∼0.30〈110〉 _p ^* , in close agreement with the condensed RUM mode found in the electron diffraction study. It is the condensation of just such a RUM mode that appears to play a major role in the various incommensurately modulated structures observed in Ba₂TiGe₂O₈, Ba₂TiSi₂O₈ and Sr₂TiSi₂O₈, respectively. Received: 26 November 2001 / Accepted: 25 May 2002 Present address: Y. Tabira Materials Characterization Laboratory Mitsui Mining & Smelting Co. Ltd. 1333-2 Haraichi, Ageo, Saitama 362-0021, Japan     

APPLICATION OF BED EVOLUTION MODELS OVER LOOSE AND RIGID AREAS

LINTRODUCTIONThesimulationofmorphodynamicsinestUariesandcoastalareasisbecauseofitSeconomicalmeritageononehandandofitSscientificcomplexityontheOtheranoutStalldingfieldofresearchanddeVelopment.TheFederalWaterwaysEngineeringandResearchinstitote(BAW)isthecentraladvisoryinstitutefortheGermanwaterwayauthority.ItisthereforereSPonsibletoprovidethescientificsuPPOrtforoptimalsedimentmanagemelltproceduresforWatCrwaymaill~ce.ThehydredynndcSystemanalysisisthemainaPProachtosupportengineeringd…     

剪力墙结构、框架填充墙结构模型模拟地震试验研究

对三种结构体系的模型，即钢筋混凝土剪力培结构、钢筋混凝土框架砖填充壤结构和钢框架混凝土填充墙结构模型，进行了地震模拟振动台试验研究．三种结构的模型均为４层，１／３几何比例，整体尺寸相同，按静力等强度原则进行设计。利用５ｍ×５ｍ液压振动台逐渐增大输入地震的峰值加速度直至模型破坏，在试验过程中测量并比较三种模型在弹性和开裂等状态时加速度、位移、应变的反应情况，并用微幅激振测定模型在相应状态下动力特性的变化，从而综合比较和研究它们的地震反应、破坏机理和抗震能力。     

综谈抗滑墙

介绍抗滑墙的种类，特点和选择原则。     

界面附近目标对柱面波的声散射

运用表面ｈｅｌｍｈｏｌｔｚ积分公式研究柱目标位于不同阻抗界面附近的声散射。根据Ｇｒｅｅ函数的定义，在两维空间中，应用Ｆｏｕｒｉｅｒ变换方法，将柱面波展开成平面波的迭加，并用越过法求解柱面波在界面上的声反射；同时定义扩展反射系数描述柱面波在平面上的反射小大，从而获得二维半无限空间Ｇｒｅｅｎ函数的表达式。     

Wave reflection and transmission by curtainwall–pile breakwaters using circular piles

This paper presents a mathematical model which computes the hydrodynamic characteristics of a curtainwall–pile breakwater (CPB) using circular piles, by modifying the model developed for rectangular piles by Suh et al. [2006. Hydrodynamic characteristics of pile-supported vertical wall breakwaters. Journal of Waterway, Port, Coastal and Ocean Engineering 132(2), 83–96]. To examine the validity of the model, laboratory experiments have been conducted for CPB with various values of draft of curtain wall, spacing between piles, and wave height and period. Comparisons between measurement and prediction show that the mathematical model adequately reproduces most of the important features of the experimental results. The mathematical model based on linear wave theory tends to over-predict the reflection coefficient as the wave height increases. As the draft of the curtain wall increases and the porosity between piles decreases, the reflection and transmission coefficient increases and decreases, respectively, as expected. As the relative water depth increases, however, the effect of porosity disappears because the wave motion is minimal in the lower part of a water column for short waves.     

三峡工程二期围堰心墙高双墙方案有限元分析

本文用自编的三维非线性程序对三峡工程二期围堰高双墙方案的应力与变形进行了有限元分析。计算模型采用双曲线应力应变关系。本次计算成果给出了围堰和防渗墙各部位的应力与位移，指出了可能出现破坏的薄弱部位。