大跨度煤场封闭结构预应力体系研究

针对顶部曲线较平缓的大跨度拱形钢结构，通过设置可抵抗拱方向荷载的张弦索和可抵抗反拱方向风吸力的斜索，形成了预应力张弦索-斜索钢桁架结构体系，同时改善了拱形结构体系在不同方向荷载作用下的受力性能。采用有限元分析与实际工程设计相结合方式，以西来峰煤化工分公司焦化厂二期储煤场封闭项目为例，对非预应力钢桁架结构体系、预应力张弦钢桁架结构体系、预应力张弦索-斜索钢桁架结构体系方案进行了体系选型研究。对上述3种结构体系的支座反力、主拱桁架弦杆轴力、结构竖向变形等方面进行对比分析，证明了张弦索-斜索钢桁架结构体系的优越性，同时针对预应力张弦索-斜索钢桁架结构体系进行了布索方案分析，分析改变张弦索和斜索锚固端位置对结构弦杆受力及变形的影响，得出了张弦索布索范围覆盖拱架上弦受压区、锚固端位置接近拱架曲率最大处时，斜索上锚固端在拱架跨度的35%~40%位置时，对结构最有利；另外对张弦索、斜索的初拉力取值进行了方案比选，得到了拉索初拉力取值对结构杆件内力的影响规律，确定了张弦索、斜索初拉力取值均为1000kN较为合理。

Study on prestressed system of long span enclosed coal shed structure

Aiming at the prestressed system of steel arch structure with flat top curve, by setting strings cable to resist loads in the direction of arch and oblique cables to resist suction wind loads, the prestressed strings cable-oblique cable steel truss structure system was formed which improved the mechanical performance of arch structure under loads in different directions. Focused on the combination of finite element analysis and practical engineering construction, the Xilaifeng Coal Chemical Company Coking Plant Phase II Coal Storage Closure Project was taken as an example. Three structure schemes were studied including the non-prestressed steel truss structure system, the prestressed strings steel truss structure system and the prestressed strings cable-oblique cable steel truss structure system. Several aspects of the three structure schemes, such as support reactions, main arch truss chord axial force, the vertical deformation, etc, were thoroughly analyzed to illustrate the priority of prestressed strings cable-oblique cable steel truss structure. The prestressed strings cable-oblique cable steel truss structure system was further analyzed. The influences of oblique cable upper end and strings cable anchor end position on structure chord force and deformation were analyzed. The most favorable design requires that the distribution of the strings cable covers the upper chord of the arch, while the strings cable end should be near to the largest arch curvature and the upper end of the oblique cable should be located at the 35%-40% span of the arch. The influence of the initial cable tension values of strings cable and oblique cable on structural internal force was studied and the reasonable initial tension value was determined as 1000 kN for both types.