Response of multilayer geosynthetic-reinforced bed resting on soft soil with stone columns

In the present study, a mechanical model has been developed to study the behavior of multilayer geosynthetic-reinforced granular fill over stone column-reinforced soft soil. The granular fill and geosynthetic reinforcement layers have been idealized by Pasternak shear layer and rough elastic membranes, respectively. The Kelvin–Voight model has been used to represent the time-dependent behavior of saturated soft soil. The stone columns are idealized by stiffer springs and assumed to be linearly elastic. The nonlinear behavior of the soft soil and granular fill is considered. The effect of consolidation of soft soil due to inclusion of the stone columns on settlement response has also been included in the model. Plane strain conditions are considered for the loading and reinforced foundation soil system. An iterative finite difference scheme is applied for obtaining the solution and results are presented in nondimensional form. It has been observed that if the soft soil is improved with stone columns, the multilayer reinforcement system is less effective as compared to single layer reinforcement to reduce the total settlement as there is considerable reduction in the total settlement due to stone column itself. Multilayer reinforcement system is effective for reducing the total settlement when stone columns are not used. However, multilayer reinforcement system is effective to transfer the stress from soil to stone column. The differential settlement is also slightly reduced due to application of multiple geosynthetic layers as compared to the single layer reinforcement system.     

钢筋混凝土框架柱侧向变形能力的研究

本文介绍了8根钢筋混凝土柱的往复荷载试验、并且与理论计算结果进行了对比，另外，通过对收集到的103根钢筋混凝土框架柱试验的数据分析。，峄影响柱位移角的因素进行了讨论，最后提出了钢筋混凝土柱位移角以及为满足变形能力要求所需箍筋量的估算方法。     

Stability Analysis of Aquatic-Sand Pile Composite Foundation Reinforcing for New Shore-Connecting Structure

The Yangshan deepwater port is the only container port built in the islands off the mainland of China. Batter piles with a sheet-pile-supported platform bulkhead structure were first used as a new shore-connecting structure to connect the front main wharf structure and the back land. Large-diameter sand columns were also used to reinforce the soft foundation of the shore-connecting structure in the deep water of the open sea. A 3D nonlinear FEM model based on real geological conditions was built to optimize the large-diameter sand columns’ reinforcing scheme and investigate shore-connecting structures’ mechanical properties under different construction conditions. The replacement ratio of 30%, the bottom elevation of the fourth soil layer, and the soft soil just below and directly adjacent to the shore-connecting structure were determined as optimal replacement ratio, reinforcing depths, and reinforcing area of the large-diameter sand columns reinforcement by assessing the force and deformation of the shore-connecting structure. By numerical computing, the maximum displacement of the supported platform was 11.03 cm, which was close to the measured value; and the piles’ maximum stress, displacement and moments were all smaller than the design strength. These indicated that the shore-connecting structure could remain stable by an optimal sand columns reinforcing scheme.     

关于日本框架柱受剪承载力公式的讨论

通过对日本抗震设计规范中有关钢筋混凝土框架柱受剪承载力代表性公式的研究，凸现了由经验公式到基于桁架一拱模型建立的发展趋势。对各公式中所包括的影响框架柱受剪承载力的主要因素(如剪跨比、轴压比、配箍率、混凝土强度、纵筋率等)进行了深入讨论，并采用框架柱受剪承载力试验数据考察了各个公式的有效性。     

轻质填充墙异型柱框架弹性阶段地震作用计算

本文在四个模型试验研究基础上，建立了轻质填充墙与异型柱框架共同工作的弹性动力计算模型，给出了结构弹性阶段地震作用的计算方法。     

Effect of soil stabilization on audible band railway ground vibration

Although railway-generated ground vibrations usually have greater energy levels at lower frequencies, vibrations in the audible range above 20 Hz can nevertheless be relevant for secondary noise problems in buildings. One countermeasure is soil stabilization under the track embankment. While effective at low frequencies, a potential side effect is amplification in some audible bands. Presented here are both experimental and theoretical assessments of the countermeasure in the audible bands. The main innovation is the treatment of an infinite periodic track–ground system, using a transfer matrix approach with a repeating element including the rail, pad, sleeper, and an underlying half-space (ballast and soil). Excitation in this band is attributed to rail and wheel roughness. The model makes successful predictions when the half-space properties are allowed to be frequency-dependent such that the dispersion of the surface wave matches that in the actual layered earth (including ballast and underlying soil layers). The field measurements are also unique in that both before and after evaluation of the countermeasure was possible.     

碳纤维布增强钢筋混凝土柱延性性能的评估与分析

在试验研究的基础上，对碳纤维布提高钢筋混凝土柱延性的机理进行了分析，确定了碳纤维布用量、轴压比、剪跨比、矩形截面柱转角部位的形状等试验因素对碳纤维布加固钢筋混凝土柱延性的影响规律。在此基础上，重点对碳纤维布加固钢筋混凝土柱延性性能的评估与分析方法进行了研究，提出了碳纤维布加固矩形截面钢筋混凝土柱位移延性比的理论计算方法和简化计算公式。计算结果与试验数据能较好地吻合。工程技术人员可以应用上述方法，对碳纤维布增强钢筋混凝土柱延性性能进行合理的评估与分析。     

ISO-834标准火灾作用后方钢管混凝土构件滞回性能试验研究

研究火灾后钢管混凝土结构的抗震性能，对于合理进行该类结构火灾后的修复具有重要意义。本文通过对6个ISO-834标准火灾作用后方钢管混凝土构件进行往复荷载作用下的荷载-变形滞回性能试验，探讨火灾作用后方钢管混凝土荷载-变形滞回曲线的特点以及刚度退化规律，并对火灾作用后方钢管混凝土压弯构件极限承载力和抗弯刚度计算方法进行了讨论。     

Experimental investigation of the earthquake response of a model of a marble classical column

Experimental results concerning the earthquake response of a marble model of a classical column are reported herein. The model was a 1: 3 scale replica of a column of the Parthenon on the Acropolis of Athens, made from the same material as the original. Several earthquake motions, scaled appropriately in order to cause significant rocking but no collapse of the column, were used as the excitation. The base motion was applied in plane (in one horizontal and the vertical direction) or in space (in two horizontal and the vertical direction), using the shaking table facility at the Laboratory for Earthquake Engineering of the National Technical University of Athens. It was found that the column might undergo large deformations during the shaking, which are not necessarily reflected by the residual displacements at the end of it. For planar excitations, significant out‐of‐plane displacements can happen, triggered by the inevitable imperfections of the specimen. It was also verified that the response is very sensitive, even to small changes of the geometry or the input motion parameters. For this reason, the experiments were not repeatable and ‘identical’ experiments produced different results. Copyright © 2002 John Wiley & Sons, Ltd.     

国家体育场斜柱测量放样原理与方法

本文用两种不同的数学方法解决国家体育场斜扭柱在任意高程上柱角点三维坐标计算问题,对斜柱现场放样的方法进行阐述。提出建筑施工测量中空间直角坐标系旋转矩阵法转换思路,并论述全站仪坐标放样限差的制定方法。