细部构造对结构风荷载影响的数值模拟分析

发布时间：2018-03-25 18:40

本文选题：数值模拟　切入点：细部构造　出处：《湖南大学》2015年硕士论文

【摘要】：结构抗风分析的主要研究方法有:现场实测、风洞试验、理论分析和CFD数值分析方法。近三十年来,伴随着计算机技术的飞速发展和流体力学理论的不断完善,基于计算流体动力学原理的CFD数值分析方法凭借其优势和应用前景在土木工程结构抗风设计的研究中越来越受到重视,并发挥着无法替代的作用。本文基于FLUENT软件平台,以建筑结构和桥梁结构为对象进行了数值风洞模拟,重点探讨了常见的细部构造对建筑结构和桥梁结构风荷载以及绕流风场的影响。本文的主要研究工作可归纳为以下几个方面:(1)以日本建筑协会(AIJ)长宽高之比为1:1:0.5的建筑模型为对象,采用大涡模拟(LES)方法对45°风向角不同类型风场作用下模型的风荷载进行了三维非稳态数值模拟计算,并将数值计算结果与风洞试验结果进行比较,验证了CFD数值计算的可靠性。在此基础上,通过在模型的不同位置加设分隔挡板探讨了45°风向角下平屋盖锥形涡的特性。同时,重点探讨了屋面加设不同高度女儿墙对风压分布的影响。结果表明,基于Q准则的旋涡判别法可较好的识别建筑物绕流场中形成的旋涡。均匀来流时锥形涡与侧面脱体涡相互作用并脱落,其作用将反馈至屋面旋涡上使屋盖两个锥形涡强度以屋面对角线为轴交替波动,此消彼长。但在湍流风场作用下,屋面锥形涡并不会出现此类波动现象。屋面女儿墙的存在会使得屋面锥形涡的间隙变窄,旋涡足迹变阔,且屋面峰值吸力随女儿墙高度的增加而迅速减小。(2)在长宽高之比为1:1:0.5的AIJ建筑模型各立面上加设阳台,并利用大涡模拟(LES)方法对其进行了数值模拟计算。计算过程中,针对不同的来流风场、不同的风向角(0°→15°→30°→45°)以及不同的阳台悬挑长度进行了系统的模拟分析。在此基础上,重点探讨了立面阳台的存在对建筑表面风压分布和绕流风场的影响。研究结果表明,阳台的存在会明显改变气流在建筑表面的分离、再附着形式,引起的风压变化主要集中在迎风面,特别是迎风面最上一排阳台及两侧阳台的区域。此外,随着来流风向角的增加,阳台对建筑迎风面上风压的影响逐渐加大。(3)采用欧拉-欧拉体系下的多相流模型,将雨滴拟设为连续介质,通过在FLUENT计算软件上编写相应的UDF计算程序,分别对典型桥梁断面节段模型和厦漳跨海大桥北汊主桥实桥模型进行了三维风驱雨的数值模拟研究。计算得到了模型周围风场和雨场分布、雨滴捕获率、雨滴冲击荷载以及桥体所受三分力等参数。然后,以矩形断面和准流线型断面节段模型为对象探讨了桥面护栏等桥面细部构造对桥梁结构绕流风场和三分力系数的影响。研究发现,雨滴对整体平均荷载的影响比较小,对三分力系数有影响,但影响并不大。桥面护栏等对雨滴冲击桥面有一定的阻碍作用,使桥面行车道受雨强度减弱,且对桥梁结构绕流风场等有着较明显的影响。(4)最后对全文所做研究工作进行了系统的总结和展望,本文的研究成果也可为实际工程结构的抗风设计提供有价值的参考。
[Abstract]:The main research methods are: structure analysis of the wind field measurement, wind tunnel test and numerical analysis method of theoretical analysis and CFD. In the past thirty years, with the rapid development of computer technology and the theory of fluid mechanics of continuous improvement, with its advantages and application prospect in the research of civil engineering structural wind resistant design is more and more important with the method of CFD the numerical analysis based on the principle of fluid dynamics, and plays an irreplaceable role. In this paper, based on the FLUENT software platform, the numerical simulation on the structure of the building and bridge as the research object, discussed the influence of common details of the building structure and bridge structure wind load and wind field around the focus of this paper. Can be summarized as follows: (1) to the Japanese Construction Association (AIJ) aspect ratio of building model for 1:1:0.5 as the object, using large eddy simulation (LES) Method for numerical simulation of three-dimensional unsteady wind angle of 45 degrees between different types of wind field model under the action of wind load, and the numerical calculation results were compared with wind tunnel test results, verify the reliability of CFD numerical calculation. On this basis, through the model in different location with dividers to discuss the properties of 45 degree of wind direction under the flat roof of the conical vortices. At the same time, focus on the roof with different height of parapet effect on the wind pressure distribution. The results show that the vortex formed around the flow field based on Q criterion method can better identify vortex structures. Uniform flow and conical vortex vortex interaction and off side, the effect will be feedback to the roof to roof two conical vortex vortex intensity in roof diagonal axis alternating fluctuation shift. But in the role of turbulent wind field, the roof does not appear this kind of conical vortex wave Dynamic phenomenon. The existence of the roofing parapet wall will make the gap narrowing of the roof conical vortex, vortex become wide and increase the footprint, roof peak suction with parapet height decreases rapidly. (2) in the aspect ratio of the facade AIJ 1:1:0.5 building model is arranged on the balcony, and using large eddy simulation (LES) a method for the numerical simulation of the calculation process, according to the different wind field, different wind angle (0 degrees, 15 degrees, 30 degrees, 45 degrees) and different balcony overhang length are simulated and analyzed systematically. On this basis, focusing on the vertical surface of the balcony the influence of wind pressure distribution and building surface wind field. The results show that the separation of the balcony there will be clearly change the air flow on the surface of building, reattachment, pressure changes mainly concentrated in the windward side, especially the windward side of the top row on both sides of the balcony and balcony Area. In addition, with the increase of flow direction, the effect of wind pressure on the windward side of the balcony on the building gradually increased. (3) using the Euler Euler multiphase model system, the raindrop ansatz for the continuous medium, through the FLUENT software on the computer program to prepare the corresponding UDF, respectively for the typical bridge section the section model and Xiazhang bridge north main bridge bridge model for numerical simulation of three dimensional wind driven rain. The calculated model of the wind and rain around the distribution of raindrop capture rate, raindrop impact load and bridge by three component parameters. Then, with rectangular section and quasi streamline section model as the object to investigate the effect of the deck of bridge fence detail structure wind field and the three component coefficient around the bridge structure. The study found that the effects of raindrops on the overall average load is relatively small, have influence on the three component coefficients, but the impact of Is not large. Deck guardrail has some effect of resistance to raindrop impact bridge, bridge lane by rain intensity, and have obvious influence on the structure of the bridge wind field. (4) at the end of this paper, the research work is summarized and prospected the research results of this paper can also be to provide valuable reference for the wind resistant design of engineering structure.

【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU312.1

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