高承台群桩基础桥墩的动水附加质量模型验证

基于不可压缩水体的假定条件,国内外研究者提出多种可供工程实用的动水力简化分析模型和计算方法,如刚性柱法、莫里森法和基频近似法等.为研究上述简化方法所得桥墩动力响应的差异,将基于不可压缩水体辐射理论得到的精确解作为标准,针对受水平地震动激励的水中弹性悬臂圆形桥墩进行地震响应的对比分析.选取对动水力有影响的水深和宽深比,通过输入3条中软土场地的地震动记录,总共设计144种不同尺寸的桥墩、水深以及地震作用工况,得到各工况下桥墩的顶部位移、底部剪力和弯矩响应.通过对顶部位移、底部剪力和弯矩响应峰值相对误差的范围、均值和变异系数的分析讨论,得到3种简化方法的计算精度,初步给出各方法的适用范围.

     

高墩桥地震碰撞效应初步研究

针对我国西部山区典型的高墩桥,建立了某桥的纤维单元模型;在各伸缩缝处梁间设置多个间隙单元模拟碰撞,采用非线性时程反应分析方法对模型进行运算,通过比较和分析计算结果,探讨了该高墩桥在不同地震波输入下的碰撞反应以及碰撞对结构的影响。分析结果表明,地震波的频谱特性与结构各部分的固有频率是影响结构碰撞反应的重要因素,碰撞在某种程度上对部分结构是有利的。     

中等跨径梁式桥型分析比较

对于中等跨径的梁式桥,通过对普通连续梁桥、V型墩连续梁桥、斜腿刚构桥三种桥型的受力特性和施工方法的比较,分析出它们截面及预应力配筋的差异。进而得出在一般条件下应优先选用斜腿刚构桥。这种桥型在受力、经济等控制因素上均具有可比性。     

包西铁路双线圆端形空心高墩设计

以包头西安铁路义南洛河特大桥双线圆端形空心高墩的施工图设计为依据,介绍了圆端形空心高墩的构造特点、设计计算方法,为同类桥墩的设计提供了指导。     

Effects of Inclination of Bridge Piers on Scouring Depth

For a safe design of a bridge pier footing, it is important to estimate the maximum depth of scour as accurately as possible. The aim of this experimental study is to investigate the effects of inclination of bridge piers on local scour depths around bridge piers. Single circular piers inclined toward the downstream direction were founded in a uniform bed material. Near threshold conditions were employed. The results of this study indicate that the local scour depth decreases as the inclination of the pier increases.     

关于短肢剪力墙设计及应用的几点探讨

对短肢剪力墙的定义及短肢剪力墙结构界定方法的讨论，对短肢剪力墙的受力特征、计算方法、配筋方法、设计应注意的问题、经济指标及连梁的设置等一些问题的理解和看法，将规范里零散的几点要求用通俗的语言来进行阐述，并用实例来进行说明。     

Unbonded Posttensioned Concrete Bridge Piers. II: Seismic Analyses

The seismic response characteristics of a proposed unbonded posttensioned concrete bridge-pier system are evaluated. Time-history analyses are carried out on prototype designs of single-column piers and two-column bents using detailed nonlinear finite-element (FE) models and equivalent single-degree-of-freedom (SDOF) systems embedded with phenomenological constitutive models. The phenomenological models are based on the hysteretic behavior of the prototype designs from cyclic analyses using nonlinear FE models, which have been calibrated and verified against experiments. The two modeling techniques are compared and evaluated for simulating the response of unbonded posttensioned bridge piers. Extensive time-history analyses are carried out on the SDOF models to study the influence of unbonded posttensioning on seismic response. To assess the adequacy of the proposed bridge-pier system, the seismic demands on the prototype designs are compared to their capacities as established in a companion paper. The applicability of current bridge design specifications to designing the proposed bridge-pier system is discussed.     

Analysis and Testing of Piles for Ship Impact Defenses

This paper deals with analyses and reduced scale tests carried out to validate the design of flexible protection structures for bridge piers against ship impact. The protection system analyzed is part of the fixed link currently under construction across the Parana River between the cities of Rosario and Victoria in Argentina, and it will protect a cable-stayed bridge and parts of the approach viaduct against impact of aberrant vessels with sizes up to 100,000 DWT. The protection system was designed on the basis of dissipated energy and consists of groups of steel-encased large diameter concrete piles connected at the top by a reinforced concrete platform. The impact energy is to be absorbed by large horizontal displacements of the pile caps that involve large deformations of the surrounding soil and geometrically and material nonlinear response of the pile shafts themselves. The paper focuses on modeling the nonlinear characteristics of the response of the structure, and on its assessment by means of 1:15 scale model tests performed in both the laboratory and in the field to account for the displacements and deformations undergone by the pile shafts.     

高拱坝表孔宽尾墩流道内水流特性的数值模拟研究

宽尾墩应用于高拱坝表孔后,其下泄水流的空中扩散特性与宽尾墩流道内的水流特性密切相关。采用k-ε双方程紊流模型对宽尾墩应用在高拱坝坝身泄洪表孔时的水流特性进行了3维数值模拟,给出了孔流道水面线、压力、流场等水流特性。计算值与模型试验值对比,两者吻合较好。计算结果发现,坝面中线压力分布与侧墙压力分布存在相似规律,所不同的是侧墙压力在宽尾墩转折点位置存在局部增大;墩尾压力分布受墩内水流流线弯曲影响,其分布不再符合净水压力分布规律;墩尾水流流速大小沿水深方向变化不大,但流速方向变化比较明显。     

不同环境荷载激励下考虑流固耦合效应的深水桥墩响应分析

为探讨不同环境荷载组合激励下,动水压力对深水桥墩结构响应的影响程度,本文基于非线性Morision方程,同时考虑附加质量效应和流固耦合效应,对深水桥墩结构在波浪、冰荷载和地震3种环境荷载单独作用下,以及不同组合形式共同作用下的结构响应进行数值分析.计算结果表明:结构各项参数,包括长细比、墩高以及水深都将会对动水压力影响...