大跨度钢结构屋盖的风雪流作用及响应

The long-span steel structural roof is widely applied in all kinds of venues, stadiums and transportation buildings.Available researches on the roof mainly focus on design and calculation under normal working loads. In recent years, many structural failure accidents of long-span roofs under snowdrift load occurred at home and abroad. However, researches on working performance of the long-span roof under extreme condition especially snowdrift load, involving a series of complicated frontier problems, progressed hardly in related fields,including kinematic mechanism of snowdrift two-phase flow, calculation of wind-induced snow pressure, coupling effect between snowdrift and structures and collapse resistance behavior of the structures. The purpose of this research is to build wall functions in near wall region of a turbulent boundary layer taking snow particles attachment into consideration, and to modify kinematic equation of the coupled motion between wind and snow; to propose topological feature models of snow particles distribution; to establish the 3D numerical fluctuating snowdrift flow field and build up equations of equivalent wind load in which the modified shape of snowdrift is considered; to propose practical parameter system for analysis of coupling effect between snowdrift and long-span roof structures, eventually,to study collapse resistance behavior of the long-span roof structures under snowdrift load. Based on the results of this research, it is expected that obvious progress would be obtained in related fields, theory support would be supplied in the snowdrift resistant designing of long-span roof structures, and the snowdrift resistant design level would be improved.

大跨度钢结构屋盖广泛用于大型场、馆、交通建筑，现有研究主要集中在正常荷载作用下的结构设计、计算。近年来，国内外发生了很多在风雪流作用下的大跨度屋盖结构破坏事故。但是，研究极端条件特别是风雪流作用下大跨度屋盖结构的工作性能同时涉及风雪两相流运动机理、风致雪压计算、风雪流-结构耦合作用、大跨度结构抗倒塌性能等学科前沿问题，国内外在这些方面目前尚未取得突破性进展。 本项目拟通过试验和数值风洞模拟，构建考虑雪颗粒附着影响的风雪流壁面函数、风雪流颗粒运动的修正公式；提出积雪模化特征模型；构建风雪流三维数值脉动流场，提出典型屋盖积雪修形后的等效风荷载计算公式；建立结构-风雪流耦合作用计算参数框架，研究典型大跨度屋盖结构在风雪作用下的抗倒塌性能。 通过本课题的研究有望在相关学科前沿方向取得重要进展，为大跨度屋盖结构抗风雪设计提供理论支撑，提高结构抗风雪设计水平。

近年来，国内外发生了很多极端风雪天气下的大跨度屋盖结构破坏事故，研究极端条件下大跨度屋盖结构的风雪流作用及响应同时涉及风雪两相流运动机理、风致雪压计算、风雪流—结构耦合作用、大跨度结构抗倒塌性能等学科前沿问题，针对此，国内外研究目前尚未取得突破性进展。. 本项目通过场地实测、试验和数值风洞模拟，研究了：大跨度屋盖在风雪流作用下的堆载特性、大跨度屋盖气动外形修正对等效风荷载的影响、风雪流数值模拟方法、大跨度屋盖结构与风雪流的耦合作用等四个方面的问题。基于48组模型试验，研究了常见建筑模型的屋盖积雪与周边积雪模式、模化雪荷载模型，并与现行国际雪荷载标准进行了比对分析；分析风雪堆积对屋面气动特性影响的不确定性，建立了雪颗粒不均匀堆积对屋盖三维形状修正的数据识别方法，分析了积雪对建筑绕流的干扰影响规律；确定了典型风雪场数值模拟优化参数构架，构建了三维脉动风雪场，提出了了基于CFD-DEM的风雪流数值模拟方法，该方法可考虑风雪耦合作用以及粒子之间的粘结、碰撞、分离滚动等；建立了基于RBF的雪相时变准稳态算法，该方法基于两相流稳态计算理论，建立了风雪相侵蚀插值算法与多阶段稳态逼近判断算法，解决了风雪相稳态时变模拟问题，相比瞬态算法大幅度提高了计算效率；揭示了积雪影响对大跨度屋盖结构流固耦合动力响应的影响规律。. 通过本课题的研究,在风雪流实测试验、数值模拟、作用机理与结构响应等几个基础科学问题上取得重要进展，为大跨度屋盖结构抗风雪设计提供了理论支撑，提高了大跨度屋盖结构的抗风雪设计水平。