In this paper, a finite element method is developed to numericallyevaluate the shear coefficient of Timoshenko's beam with multiplyconnected cross section. With focus on analyzing shear stressesdistributed at the ...In this paper, a finite element method is developed to numericallyevaluate the shear coefficient of Timoshenko's beam with multiplyconnected cross section. With focus on analyzing shear stressesdistributed at the neutral axis of the beam, an improved definitionof the shear coeffi- cient is presented. Based on this definition, aGalerkin-type finite element formulation is proposed to analyze theshear stresses and shear deflections. Numerical solutions of theexamples for some typical cross-sections are compared with thetheoretical results. The shear coefficient of tower sections of theTsing Ma Bridge is calculated by use of the proposed approach, sothat the finite element modeling of The bridge can be developed withthe accurate values of the sectional properties.展开更多
In most framed structures anticipated deformations in accordance with current codes fall into acceptable limit states, whereas they go through substantial residual deformations in the aftermath of severe ground motion...In most framed structures anticipated deformations in accordance with current codes fall into acceptable limit states, whereas they go through substantial residual deformations in the aftermath of severe ground motions. These structures seem unsafe to occupants since static imminent instability in the immediate post-earthquake may be occurred. Moreover, rehabilitation costs of extensive residual deformations are not usually reasonable. Apparently, there is a lack of detailed knowledge related to reducing residual drift techniques when code-based seismic design is considered. In this paper, reduced beam section connections as a positive approach are taken action to mitigate the huge amount of residual drifts which are greatly amplified by P-Δ effects. To demonstrate the efficacy of RBS, a sixteen-story moment resisting frame is analyzed based on a suite of 8 single-component near field records which have been scaled according to the code provisions. The results are then processed to assess the effects of RBS detailing on drift profile, maximum drift, and residual drift. Besides, a special emphasis is given to estimate overall trend towards drift accumulation in each story in the presence of RBS assembly. A main conclusion is that using this connection predominantly alleviates the adverse effects of P-Δ on amplifying residual drifts.展开更多
针对凤凰颈排灌站下游出口斜向汇入船闸下游口外连接段,其调度运行方式对通航水流条件产生不利影响。通过整体定床物理模型试验,系统研究了凤凰颈强排泵站在不同调度运行方式下对船闸下游口外连接段通航水流条件的影响规律。试验结果表...针对凤凰颈排灌站下游出口斜向汇入船闸下游口外连接段,其调度运行方式对通航水流条件产生不利影响。通过整体定床物理模型试验,系统研究了凤凰颈强排泵站在不同调度运行方式下对船闸下游口外连接段通航水流条件的影响规律。试验结果表明:在西河侧向长江排水的自排工况下,水流斜向汇入船闸下游连接段,导致交汇区最大横向流速达0.48 m s,对连接段通航水流条件影响较大;相比之下,在长江侧向西河引水的机引工况下,横向流速仅为0.28 m s,影响程度较小。研究进一步发现,长江侧水位越低,排灌站出流对连接段通航水流条件的影响越显著。以自排工况为最不利工况,研究提出泵站引排水渠与连接段之间增设透空导流墙的工程优化方案,试验表明该措施可有效将横向流速控制在0.30 m s以内。展开更多
文摘In this paper, a finite element method is developed to numericallyevaluate the shear coefficient of Timoshenko's beam with multiplyconnected cross section. With focus on analyzing shear stressesdistributed at the neutral axis of the beam, an improved definitionof the shear coeffi- cient is presented. Based on this definition, aGalerkin-type finite element formulation is proposed to analyze theshear stresses and shear deflections. Numerical solutions of theexamples for some typical cross-sections are compared with thetheoretical results. The shear coefficient of tower sections of theTsing Ma Bridge is calculated by use of the proposed approach, sothat the finite element modeling of The bridge can be developed withthe accurate values of the sectional properties.
文摘In most framed structures anticipated deformations in accordance with current codes fall into acceptable limit states, whereas they go through substantial residual deformations in the aftermath of severe ground motions. These structures seem unsafe to occupants since static imminent instability in the immediate post-earthquake may be occurred. Moreover, rehabilitation costs of extensive residual deformations are not usually reasonable. Apparently, there is a lack of detailed knowledge related to reducing residual drift techniques when code-based seismic design is considered. In this paper, reduced beam section connections as a positive approach are taken action to mitigate the huge amount of residual drifts which are greatly amplified by P-Δ effects. To demonstrate the efficacy of RBS, a sixteen-story moment resisting frame is analyzed based on a suite of 8 single-component near field records which have been scaled according to the code provisions. The results are then processed to assess the effects of RBS detailing on drift profile, maximum drift, and residual drift. Besides, a special emphasis is given to estimate overall trend towards drift accumulation in each story in the presence of RBS assembly. A main conclusion is that using this connection predominantly alleviates the adverse effects of P-Δ on amplifying residual drifts.
文摘针对凤凰颈排灌站下游出口斜向汇入船闸下游口外连接段,其调度运行方式对通航水流条件产生不利影响。通过整体定床物理模型试验,系统研究了凤凰颈强排泵站在不同调度运行方式下对船闸下游口外连接段通航水流条件的影响规律。试验结果表明:在西河侧向长江排水的自排工况下,水流斜向汇入船闸下游连接段,导致交汇区最大横向流速达0.48 m s,对连接段通航水流条件影响较大;相比之下,在长江侧向西河引水的机引工况下,横向流速仅为0.28 m s,影响程度较小。研究进一步发现,长江侧水位越低,排灌站出流对连接段通航水流条件的影响越显著。以自排工况为最不利工况,研究提出泵站引排水渠与连接段之间增设透空导流墙的工程优化方案,试验表明该措施可有效将横向流速控制在0.30 m s以内。
