Cause Analysis And Reinforcement Of Beam-column Damage In Certain Underground Garage

Facing the contradiction between the lack of urban land resources and the increasing demand for urban space,China has vigorously promoted the development of urban underground space since the 13th Five-Year Plan.With the continuous development of underground building construction,in recent years,structural destructive accidents have occurred frequently in China’s underground structures during actual construction.The damage of such components is similar but the causes of damage are different.In order to reduce the occurrence of such engineering accidents,this article explores the cause of structural damage by analyzing a case of damage to the underground garage under construction,and selects the best reinforcement plan for it,with a view to providing design and construction guidance and reference for similar projects.Based on the structural safety appraisal method and the destruction criteria of reinforced concrete members,combined with the design data,construction background and on-site inspection results,the finite element analysis model of the underground garage structure under the actual construction environment was established,and the internal force distribution rule and failure manifestation of underground garage under different influence factors was analyzed.By comparing the actual crack distribution state,crack form and model analysis results,the correctness of the cause analysis is verified.It is concluded that the large number of horizontal cracks at the end of the column in the underground garage are mainly due to the temperature effect and long-term overloading of the roof,which cause stress concentration at the position of the quality defect of the construction joint at the end of the column.It is proposed that when made using a local carrier in the top plate stack construction,full-span stacking is used as far as possible to reduce the damage range of small eccentric compression columns;the lateral restraint strength of vertical support members should be controlled as much as possible,and the flexural shear capacity of members should be enhanced to reduce the influence of temperature.Based on the basic ideas and principles of reinforcement design,according to the actual reinforcement requirements of damaged columns,the reinforcement method of increasing cross-section and the reinforcement method of steel encasement are selected to meet the requirements.Combined with YJK appraisal reinforcement module,two reinforcement schemes are preliminarily determined.Using ABAQUS finite element software,two kinds of reinforced column models are established to simulate the actual stress situation of columns by two loading methods,namely vertical displacement and bias pressure.By analyzing the reaction force-displacement curve of the comparison column,the equivalent plastic accumulation PEEQ diagram and the equivalent stress MISES cloud diagram,it is concluded that the enlarged section method is superior to the outsourced steel method.The scheme has been applied in practical engineering and achieved good reinforcement effect and economic effect.