既有砌体结构基于性能的抗震加固研究

Research on Performance-based Seismic Strengthening of Existing Masonry Structures

对结构1和结构2分别进行人工波、天津波和迁安波作用下的多遇烈度、设防烈度和罕遇烈度时程分析,对不满足性能目标要求者进行抗震加固分析。加固结果表明:①加固后最大位移角所在楼层位置出现下移现象;②上层加固效果比下层加固效果明显;③结构有无圈梁和构造柱对抗震性能的影响较大,圈梁和构造柱的截面尺寸变化对抗震性能的影响较小;④加固效果随地震波不同而不同,采用相同的加固方案加固效果不同;⑤必须根据具体的鉴定结果选用合理的加固方案,否则适得其反。

There are many existing masonry structures in China. This structural material has low intensity and poor ductility. Substandard design, nonstandard construction, aging, and higher per- formance requirements mean that the safety of existing masonry structures cannot be guaranteed. The large cost of rebuilding and the huge impact on daily life and the environment make perform- ance-based seismic strengthening studies of existing masonry structures necessary. This article discusses the architectural seismic performance, seismic time-history analysis, structural strength- ening, and strength optimum of existing masonry structures, thus supplying reliable technical lit- erature for practical application in engineering and revision of the related criterion. Several issues are discussed. （1） Some issues in the detection, evaluation,and strengthening of existing masonry structures are summarized, the deficits and contradictions in the detection, evaluation, and strengthening of existing masonry structures in terms of the current specifications and software for calculation are analyzed, and a homologous solution is proposed. （2} In agreement with the earthquake levels for new structures, earthquake levels for structures with a continuous seismic working life of 30 or 40 years for conditions of frequent earthquakes, anti-seismic fortification earthquake,and rare earthquakes are proposed. The factors affecting the anti-seismic capability level of buildings, such as structural importance, social impact, casualties, structural damage, in- house facility damage, and direct and indirect economic loss are also considered. Every factor is graded and its anti-seismic capability level is quantized. The structural performance objectives are serialized,and a relation between the capability level value and the limiting value of the story drift angles is proposed. （3） On the basis of the site condition and structural condition, screen strong shock＇s recorded wave and artificial fitting wave, Tianjin seismic waves, Qian＇ an seismic waves and artificial seismic wave can be in better agreement with the physical condition. In line with lo- cal earthquake level,adjust peak acceleration of Tianjin seismic waves, Qian＇an seismic waves and artificial seismic wave in frequent earthquake, anti-seismic fortification earthquake and rare earth- quake. Analyze the effective duration, and obtain proper seismic wave time-histories acceleration. （4） To simplify the practical engineering and establish a finite element model, dynamic and time- historical analysis is carried out for two structures using worked Tianjin seismic waves, Qian＇an seismic waves and artificial seismic waves. The corresponding maximum displacements of three panel points for every layer of the structures are measured. The average value is used to reflect the displacement of each floor,and the maximum story drift angle is compared with the perform- ance objective. The results show that the anti-seismic performance requirements are not satisfied in either structure, and they should be strengthened. The results of strengthening are ： （ 1 ） the lo- cation of the maximum displacement angle of a floor moves down after strengthening; （2） the re- inforcement effect is clearer in the superstratum than in the substratum;（3） the presence of ring beams and constructional columns has a greater effect on the anti-seismic properties;the sectional dimensions of ring beams and constructional columns have less of an effect on the anti-seismic properties; （4） the reinforcement effect is determined by the seismic waves. Different results are obtained for the same reinforcement scheme for different seismic waves： （5） the anti-seismic prop- erties will not be improved by all strengthening methods. A reasonable strengthening scheme must be selected, or the effect will be counterproductive.