巨型钢框架复合支撑体系的拉索预拉力预估理论

Determination theory on cable initial pre-stress of mega steel frame and pre-stressed composite brace structure

如何确定拉索预拉力是巨型钢框架-预应力复合支撑体系的关键问题。首先基于拉索作用建立拉索预拉力的确定准则,然后依据简化的弹簧模型,详细推导了竖向荷载和预拉力作用下,复合支撑内力增量方程,最后基于预拉力确定准则和结构变形叠加原理建立了拉索预拉力的确定理论。研究表明,拉索预拉力应确保竖向荷载作用下复合支撑内力增量平衡,并确保最不利工况下拉索具有剩余拉力;拉索预拉力必须从顶部大层往下逐层求解;建立的预拉力确定理论可为巨型钢框架-预应力复合支撑体系的初步设计及定性评判奠定理论基础。

How to determine cable initial pre-stress is one of the key problems of mega steel frame and pre- stressed composite brace structure. Fisrtly,the determination rules for the initial pre-stress were presented based on the cable function. Secondly,according to the simplified model, the balanced equations of the in- ner force increment of the composite brace were established under vertical load and pre-stress. Finally,the qualitative estimation theory on the cable initial pre-stress was determined based on the above rules and the superposition principle of structural deformation. The results indicate that the pre-stress should ensure the inner force increment in composite brace under vertical load to be in balance state,and that the stress of ca- ble still remains in the worst case. And the resolving of the pre-stress should be from the top to the bot- tom. The proposed theory on the cable initial pre-stress is useful for primary design and performance judgement for the new structure.