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1.
简要对预应力混凝土连续刚构桥桥型和结构尺寸的选择、设计以及结构受力分析进行了介绍.大桥采用主跨为85 m的预应力混凝土连续刚构桥,主梁采用单箱单室变截面箱型梁,配置三项预应力体系,下部结构采用矩形薄壁空心墩,钻孔桩基础.通过对该桥进行结构分析,桥梁各部分均满足规范要求,具有较好的安全性能.总结该桥的设计要点,为其他同类桥梁设计提供参考. 相似文献
2.
李秀云 《石家庄铁路工程职业技术学院学报》2014,(1):53-57
四川雅砻江卡拉至杨房沟水电站交通专用公路洪水沟大桥由于地形限制,在桥墩施工时,施工便道无法修至各桥墩处。要在比桥墩承台高96 m的0#桥台附近开挖施工平台,安装混凝土拌和设备,采取特殊措施将混凝土输送到桥墩附近的施工平台,再用高压混凝土输送泵泵送混凝土到桥墩上。项目采用混凝土输送泵结合缓冲溜管,成功解决混凝土垂直向下、水平、向上输送问题,保证工程质量,加快施工进度。该技术对其他类似工程具有借鉴作用。 相似文献
3.
欧智菁俞杰林上顺王金泽 《福建工程学院学报》2019,(6):511-517
以黄桷湾特大桥为工程背景,选取轴压比、梁墩刚度比、系梁布置形式及柱肢混凝土强度等级为设计参数,应用Midas Civil有限元软件构造了20座三跨对称桥梁计算模型。研究E1地震作用下钢管混凝土双肢格构墩连续梁桥主要控制截面参数地震响应,探讨各设计参数对钢管混凝土双肢格构墩连续梁桥抗震性能的影响规律,并对全桥进行优化验证。研究结果表明:轴压比对地震作用下结构内力和位移有一定影响,建议控制在0.15~0.25;梁墩刚度比对结构的抗震性能影响较大,控制在4.08~10.90时结构的内力分布更加合理;核心混凝土的强度在C40~C50时取值较为合理。 相似文献
4.
某混合梁斜拉桥钢混接合段整体有限元分析研究 总被引：1，自引：0，他引：1
在大跨度的桥梁中,单一的混凝土梁或者钢梁都会在边跨墩顶产生负反力,并会引起塔顶和主跨产生过大的偏移位移及挠度。为了充分发挥混凝土材料的压重作用和钢材跨越能力大的优势,便产生了混合梁结构,混合梁即在中孔大跨全部或部分采用钢主梁,两侧采用预应力混凝土主梁。主要采用有限元分析的方法对某混合斜拉桥钢混接合段的受力特性进行分析,真实反映其结构的复杂应力分布情况,并提出改进和完善的钢混接合构造措施。 相似文献
5.
This paper proposes a new approach for multi-objective robust control. The approach extends the standard generalizedl
2 (Gl
2) and generalizedH
2 (GH
2) conditions to a set of new linear matrix inequality (LMI) constraints based on a new stability condition. A technique for
variable parameterization is introduced to the multi-objective control problem to preserve the linearity of the synthesis
variables. Consequently, the multi-channel multi-objective mixed Gl
2/GH
2 control problem can be solved less conservatively using computationally tractable algorithms developed in the paper.
Project supported by the National Natural Science Foundation of China (No. 60374028), and the Scientific Research Foundation
for Returned Overseas Chinese Scholars, Ministry of Education (No. [2004]176) 相似文献
6.
针对基于 Pareto 支配的低维多目标进化算法在求解 3 个以上目标的高维多目标时出现收敛压力不足等问题,将调和模型中面向排序的 ELECTRE-III 引入高维多目标进化方法中,提出一种新的锦标赛选择算子。该算子包含两层操作,分别是快速非支配分层操作和同一非劣层中的赋值级别高于关系排序操作。将这种赋值级别高于关系构造的 ELECRE-III 排序法嵌入 NSGA-II 中并应用于高维多目标进化个体的优劣排序。对典型高维测试集 WFG 函数进行仿真实验,验证该高维多目标调和进化算法的有效性。 相似文献
7.
Jun-hai SHI Zhi-dan ZHONG Xin-jian ZHU Guang-yi CAO 《浙江大学学报(A卷英文版)》2008,9(3):401-409
This study presents a robust design method for autonomous photovoltaic （PV）-wind hybrid power systems to obtain an optimum system configuration insensitive to design variable variations. This issue has been formulated as a constraint multi-objective optimization problem, which is solved by a multi-objective genetic algorithm, NSGA-II. Monte Carlo Simulation （MCS） method, combined with Latin Hypercube Sampling （LHS）, is applied to evaluate the stochastic system performance. The potential of the proposed method has been demonstrated by a conceptual system design. A comparative study between the proposed robust method and the deterministic method presented in literature has been conducted, The results indicate that the proposed method can find a large mount of Pareto optimal system configurations with better compromising performance than the deterministic method. The trade-off information may be derived by a systematical comparison of these configurations, The proposed robust design method should be useful for hybrid power systems that require both optimality and robustness. 相似文献
8.
Carbon fiber reinforced polymer(CFRP)bars were prestressed for the structural strengthening of 8 T-shaped rein-forced concrete (RC)beams of a 21-year-old bridge in China.The ultimate bearing capacity of the existing bridge after retrofit was discussed on the basis of concrete structures theory.The flexural strengths of RC beams strengthened with CFRP bars were controlled by the failure of concrete in compression and a prestressing method was applied in the retrofit.The field construction processes of strengthening with CFRP bars-including grouting cracks,cutting groove,grouting epoxy and embedding CFRP bars,surface treating,banding with the U-type CFRP sheets,releasing external prestressed steel tendons-were introduced in detail.In order to evaluate the effectiveness of this strengthening method,field tests using vehicles as live load were applied before and after the retrofit.The test results of deflection and concrete strain of the T-shaped beams with and without strengthening show that the capacity of the repaired bridge,including the bending strength and stiffness,is enhanced.The measurements of crack width also indicate that this strengthening method can enhance the durability of bridges.Therefore,the proposed strengthening technology is feasible and effective. 相似文献
9.
彭玉军 《石家庄铁路工程职业技术学院学报》2014,(1):39-43
四川雅砻江卡拉至杨房沟水电站交通专用公路洪水沟大桥桥墩施工时,利用2台10 t缆索吊吊运材料、设备,墩侧安装塔吊提升桥墩模板,缓冲溜管配合混凝土输送泵浇筑混凝土。安全、快速地完成了墩柱施工,保证工程质量,加快施工进度。该技术对其他类似工程具有借鉴作用。 相似文献
10.
Carbon fiber reinforced polymer （CFRP） bars were prestressed for the structural strengthening of 8 T-shaped reinforced concrete （RC） beams of a 21-year-old bridge in China. The ultimate bearing capacity of the existing bridge after retrofit was discussed on the basis of concrete structures theory. The flexural strengths of RC beams strengthened with CFRP bars were controlled by the failure of concrete in compression and a prestressing method was applied in the retrofit. The field construction processes of strengthening with CFRP bars including grouting cracks, cutting groove, grouting epoxy and embedding CFRP bars, surface treating, banding with the U-type CFRP sheets, releasing external prestressed steel tendons-were introduced in detail. In order to evaluate the effectiveness of this strengthening method, field tests using vehicles as live load were applied before and after the retrofit. The test results of deflection and concrete strain of the T-shaped beams with and without strengthening show that the capacity of the repaired bridge, including the bending strength and stiffness, is enhanced. The measurements of crack width also indicate that this strengthening method can enhance the durability of bridges. Therefore, the proposed strengthening technology is feasible and effective. 相似文献
11.
唐杨 《长江工程职业技术学院学报》2020,(1):1-4
以某座V形墩连续刚构桥为工程背景,建立V形墩连续刚构桥0号块的ANSYS有限元模型,对拆除支架后V形墩0号块在自重工况下的变形和应力进行分析,同时对V形墩的夹角和厚度在自重工况下的影响进行了研究。研究表明V形墩的下内隅、0号块主梁的跨中截面下缘、箱梁翼板根部截面上缘以及V形墩与主梁的夹角位置可能出现较高拉应力;V形墩的夹角对V形墩0号块的受力影响较为显著,在V形墩夹角较大的情况下,主梁与V形墩之间的夹角建议采用圆弧形,避免应力集中造成节点位置混凝土开裂。 相似文献
12.
多目标进化算法常用于解决较复杂的多目标优化问题,该类算法是基于种群的进化算法,通过产生一组近似Pareto最优解集满足决策者偏好。介绍了多目标优化问题背景知识及相关定义,根据评价指标衡量解集特性,将现有算法性能评价指标分为3类并分别进行阐述,分析、比较其特点与区别。 相似文献
13.
The problem of adaptive multi-objective optimization(AMOO) has received extensive attention due to its practical significance.An important issue in optimizing a multi-objective system is adjusting the weighting coefficients of multiple objectives so as to keep track of various conditions.In this paper,a feedback structure for AMOO is designed.Moreover,the reinforcement learning combined with hidden biasing information is applied to online tuning weighting coefficients of objective functions.Finally,the prop... 相似文献
14.
This paper deals with a multi-objective parameter optimization framework for energy saving in injection molding process. It
combines an experimental design by Taguchi’s method, a process analysis by analysis of variance (ANOVA), a process modeling
algorithm by artificial neural network (ANN), and a multi-objective parameter optimization algorithm by genetic algorithm
(GA)-based lexicographic method. Local and global Pareto analyses show the trade-off between product quality and energy consumption.
The implementation of the proposed framework can reduce the energy consumption significantly in laboratory scale tests, and
at the same time, the product quality can meet the pre-determined requirements. 相似文献
15.
Modeling and multi-objective optimization of a gasoline engine using neural networks and evolutionary algorithms 总被引：1，自引：0，他引：1
José D.MARTNEZ-MORALES Elvia R.PALACIOS-HERNNDEZ Gerardo A.VELZQUEZ-CARRILLO 《浙江大学学报(A卷英文版)》2013,14(9):657-670
In this paper, a multi-objective particle swarm optimization （MOPSO） algorithm and a nondominated sorting genetic algorithm II （NSGA-II） are used to optimize the operating parameters of a 1.6 L, spark ignition （SI） gasoline engine. The aim of this optimization is to reduce engine emissions in terms of carbon monoxide （CO）, hydrocarbons （HC）, and nitrogen oxides （NOx）, which are the causes of diverse environmental problems such as air pollution and global warming. Stationary engine tests were performed for data generation, covering 60 operating conditions. Artificial neural networks （ANNs） were used to predict exhaust emissions, whose inputs were from six engine operating parameters, and the outputs were three resulting exhaust emissions. The outputs of ANNs were used to evaluate objective functions within the optimization algorithms： NSGA-II and MOPSO. Then a decision-making process was conducted, using a fuzzy method to select a Pareto solution with which the best emission reductions can be achieved. The NSGA-II algorithm achieved reductions of at least 9.84%, 82.44%, and 13.78% for CO, HC, and NOx, respectively. With a MOPSO algorithm the reached reductions were at least 13.68%, 83.80%, and 7.67% for CO, HC, and NOx, respectively. 相似文献
16.
This paper proposes a new approach for multi-objective robust control.The approach extends the standard generalized l2(Gl2)and generalized H2(GH2)conditions to a set of new linear matrix inequality(LMI)constraints based on a new stability condition.A technique for variable parameterization is introduced to the multi-objective control problem to preserve the linearity of the synthesis variables.Consequently,the multi-channel multi-objective mixed Gl2/GH2 control problem can be solved less conservatively using computationally tractable algorithms developed in the paper. 相似文献
17.
INTRODUCTION In the past two decades, a large number ostrategies for control systems analysis and synthesis such as H2, H∞, l1 and μ-synthesis had beendeveloped. In H∞design, all disturbances arelumped into a single norm rather than boundedseparately by the size of each disturbance as ||d||2=||d1||2 … ||dm||2. This certainly leads to some conservatism (D’Andrea, 1999). In contrast, theμ-synthesis technique overcomes the conservatismby introducing structured uncertainty block… 相似文献
18.
The seismic analysis of a rigid-framed prestressed concrete bridge in Tianjin Light Railway is performed. A 3-D dynamic finite element model of the bridge is established considering the weakening effect caused by the soft soil foundation. After the dynamic characteristics are calculated in terms of natural frequencies and modes, the seismic analysis is carried out using the modal response spectrum method and the time-history method, respectively. Based on the calculated results, the reasonable design values are finally suggested as the basis of the seismic design of the bridge, and meanwhile the problems encountered were also analyzed.Finally, some conclusions are drawn as ：1 ) Despite the superiority of rigid-framed prestressed concrete bridge,the upper and lower ends of the piers of the bridge are proved to be the crucial parts of the bridge, which are easily destroyed under designed earthquake excitations and should be carefully analyzed and designed; 2) The soft soil foundation can possibly result in rather weakening of the lateral rigidity of the rigid-framed bridge, and should be paid considerable attention; 3) The modal response spectrum method, combined with time-history method, is suggested for the seismic analysis in engineering design of the rigid-framed prestressed concrete bridge. 相似文献
19.
A multi-objective optimization of non-uniform beams is presented for minimum radiated sound power and weight. The transfer matrix method is used to compute the structural and acoustic responses of a non-uniform beam accurately and efficiently. The multi-objective particle swarm optimization technique is applied to search the Pareto optimal solutions that represent various compromises between weight and sound radiation. Several constraints are imposed, which substantially reduce the volume fraction of feasible solutions in the design space. Two non-uniform beams with different boundary conditions are studied to demonstrate the multi-objective optimal designs of the structure. 相似文献
20.
贪心算法与动态规划的比较 总被引：3，自引：0，他引：3
介绍了计算机算法设计的两种常用算法思想:贪心算法与动态规划算法。通过介绍两种算法思想的基本原理,比较两种算法的联系和区别。通过背包问题对比了两种算法的使用特点和使用范围。 相似文献