爆炸荷载作用下大跨预应力混凝土框架动力响应分析

Analysis of the dynamic response of prestressed concrete frame structures under blast load

为了研究预应力混凝土(prestressed concrete,PC)框架结构的抗爆性能,利用有限元软件LS-DYNA对一栋3层2跨的大跨有/无黏结PC框架结构在不同比例距离的外部远爆荷载作用下的动力响应进行了分析。分析结果表明:混凝土预应力框架在地表远爆荷载作用下,最大层间位移角与前墙所受峰值反射超压近似成线性关系;有黏结混凝土预应力框架结构层间位移角相较于无黏结混凝土预应力框架更小,损伤分布更均匀,结构抗爆性能更好;基于分析结果,给出了不同比例距离对应的损伤状态,可用于对混凝土预应力框架结构进行爆炸损伤状态快速评估。

To study the anti-blast performance of prestressed concrete(PC)frame structure,the dynamic response of a 3-story 2-span long-span bonded/unbonded PC frame structure under the action of external remote blast loads of different scaled distances was analyzed using the finite element software LS-DYNA.In the different blast conditions,the type of explosion was a surface detonation,the explosion distance was 100 m,and the scaled distances were 2−8 m/kg1/3.Explosive loads on the building surface were calculated according to unified facilities criteria 3-340-02.The different types of prestress in the numerical model were realized by controlling the direction of coupling of concrete and prestressing tendons.To validate the numerical model,the results of the numerical simulations were compared with the experimental results.The blast resistance mechanism,story drift ratios,structural damage mode,and damage assessment of PC frames were analyzed under blast loads at different scaled distances.The analysis results show that the ground floor of the large-span PC frame is easy to damage under the action of the external remote blast load,and the ground floor columns can be strengthened to improve the overall structural blast resistance.In the PC frame,columns relative to the frame beams are weaker and prone to damage.The PC frame structure with a low degree of redundancy is easy to collapse.The maximum story drift ratio of the prestressed concrete frame under the surface blast load is approximately linearly related to the peak reflected overpressure applied to the front wall.Compared with the unbonded prestressed concrete frame,the bonded prestressed concrete frame structure has a smaller story drift ratio,more uniform damage distribution,and better structural blast resistance.Based on the analysis results,the damage states at different scaled distances was given,which can realize the rapid assessment of the explosion damage state of prestressed concrete frame structures.