Research On Influence Of Uper Wall Stiffness On Uneven Settlement In Bottom Frame-masonry Structure

Uneven sett lement o f buildings is a co mmo n accident in pro jects. Due to the large-scale infrastructure construct ion o f our country, the construct ion land has decreased, many buildings inevitably located in bad foundat ion, and wit h a variet y o f other reasons, the uneven settlement accident has been difficult to eliminate. Serious uneven sett lement could cause the cracking, inclinat ion, deformat ion or even co llapse of buildings, result ing in loss o f life and property.At present, there are a lot o f research about the causes and prevent ion methods o f the uneven sett lement, some o f which have achieved good applicat ion value in engineering. The deformat ion and destruct ion o f uneven sett lement, is the result o f interact ion, redistribution o f internal forces and deformation coordinat ion between foundat ion and superstructure. Most of the rese arch on interact ion between foundatio n and superstructure is about concrete frame and steel frame structure. Due to the co mplex material mechanics performance, there is little research on masonry structure. Therefore, by the study o f interact ion between fo undat ion and superstructure based o n the finite element method, this thesis will make a deep analysis on influence of upper wall st iffness on uneven sett lement in botto m frame-masonry structure.First ly, the situat ion and research status o f the uneven sett lement o f buildings at ho me and abroad will be introduced in this thesis. The main reason o f the uneven settlement will be summed up fro m the aspects of foundation and superstructure, and describes the damage characterist ics caused by uneven sett lement.Secondly, the established method of finite element model o f masonry structure, cho ice o f element t ype, material propert ies and related parameters and model assumpt ions and so on will be discussed and analyzed. The t ypical uneven sett lement forms o f bottom frame-masonry structure will be introduced.Based on the finite element analysis, this thesis focuses on influence o f upper wall st iffness on uneven sett lement in botto m frame-masonry structure. Simplified 3D models o f the interact ion o f the superstructure and foundat ion in the condit ion o f gravit y loads will be established, and on the basis of 5 t ypical uneven sett lement forms, the value of settlement and axial fo rce of frame co lumns on response o f superstructure st iffness will be studied. Uper wall st iffne ss adjust by changing the elastic modulus. The results show that, no matter what kind o f sett lement, increasing the upper wall st iffness can reduce uneven foundat ion sett lement, and it has the best results when improving the second layer wall st iffness.The co mmo n methods o f the prevent ion and contro l o f uneven settlement in the geo logical survey and design stage will be summarized,which includes the treat ment measures o f foundation and superstructure. In the reinforcement of superstructure, not only must the treat ment effect be considered, but it is also necessary to take the econo mic and environmental issues into account. If all o f the cracking wall are reinforced, it will lead to high cost and the waste o f resources. The effects o f co mposite wall elast ic modulus when strengthening wall wit h high-performance ferrocement laminate will be studied, the results show that, the reinforcement metho d can effect ively improve the elast ic modulus o f the co mposite wall and be used for the treat ment o f uneven settlement.The last part o f this thesis introduces a case o f uneven sett lement o f botto m frame-masonry structure, analyses the causes o f the accident, put forward the co mprehensive reinforcement scheme co mbining the related content o f this thesis, which includes t he ground, foundat ion and superstructure reinforcement etc, and provides the reference for similar accident.