霞田文体园体育场单层索网设计

Design of Single-Layer Cable Net for Xiatian Stadium

霞田文体园体育场位于福建省泉州市德化县,其结构由下部的钢筋混凝土框架看台和上部的单层索网组成。单层索网采用马鞍形双曲面形态,沿看台前后方向设置向下凹的承重索,沿看台左右方向设置向上凸的抗风索,承重索与抗风索通过索夹相互连接,并通过索夹的抗滑移能力确保承重索和抗风索在相交位置不产生滑移。上部单层索网采用刚性和柔性混合边界约束形式。刚性边界为看台上方支承于钢斜柱顶的梁端落地的钢拱,柔性边界由看台前方支承在钢桅杆上的环索和看台两侧支承于钢桅杆和基础上的边索组成。承重索和抗风索采用投影面正交正放布置,投影方向间距约7 m。由于单层索网属于全柔性结构体系,在施加预应力之前,结构刚度为零且不能承担任何荷载。因此,在索网计算分析之前必须根据建筑预期的形状对索网进行找形分析。通过索网找形确定索网形态和初始应力状态,施加了初始应力状态的索网拥有承担外荷载的能力。在索网完成找形分析后,即可对索网根据不同的荷载和作用工况进行静力计算、多遇地震弹性计算、罕遇地震弹塑性计算。通过建筑与结构的多轮优化与计算,确定了柔性索网的边界条件和三维形态;利用力密度法和扩展力密度法的基本原理,编制了用于复杂索网找形的基本程序,并在项目实践中取得良好的效果;采用三维有限元分析和抗滑移试验对关键节点进行了承载力和变形校核。综合以上分析,结果表明本项目单层索网的结构选型基本合理,设计成果满足现行国家规范要求。

Xiatian Sports Park Stadium is located in Dehua County,Quanzhou City,Fujian Province.Its structure consists of a reinforced concrete frame stand in the lower part and a single-layer cable net in the upper part.The single-layer cable net is in a saddle-shaped hyperboloid form,the bearing cables which are concave downwards are arranged along the successive directions of the stand,the wind-resistant cables which are convex upwards are arranged along the left and right directions of the stand,the bearing cables and the wind-resistant cables are mutually connected through cable clamps,and the anti-slip capability of the cable clamps ensures that the bearing cables and the wind-resistant cables do not slip at the intersection positions.The upper single-layer cable net adopts a rigid and flexible mixed boundary constraint form.A rigid boundary is a floor-type steel arch support on a steel inclined column above that stand,and a flexible boundary is compose of a hoop cable supported on a steel mast in front of the stand and side cables supported on the steel mast and a foundation at two side of the stand.The bearing cable and the wind-resistant cable are arranged orthogonally on the projection plane,and the spacing in the projection direction is about 7 m.Because the single-layer cable net is a fully flexible structural system,the structural stiffness is zero and can not bear any load before the prestress is applied.Therefore,the form-finding analysis of the cable net must be carried out according to the expected shape of the building before the calculation and analysis of the cable net.The shape of the cable net and the initial stress state are determined by the form-finding of the cable net,and the cable net with the initial stress state has the ability to bear the external load.After the form-finding analysis of the cable net is completed,the static calculation,the small earthquake elastic calculation and the large earthquake elastic-plastic calculation of the cable net can be carried out according to different loads and action conditions.Through several rounds of optimization and calculation,the boundary conditions and three-dimensional shape of the flexible cable net are determined,and by using the basic principles of the force density method and the extended force density method,the basic program for the form-finding of the complex cable net is compiled and finally used in this project with good results;The bearing capacity and deformation of key joints are checked by three-dimensional finite element analysis and anti-slip test.The above analysis results show that the structural selection of the single-layer cable net of this project is basically reasonable,and the design results meet the requirements of the current national specifications.