| With the advantages of both beautiful appearance and standardized production,the hidden frame glass curtain wall is widely used in modern urban high-rise and super high-rise buildings.The glass panel of the hidden frame glass curtain is fixed on the main structure through two kinds of connection on the boundaries,one is the glued connection provided by the structural silicone sealant,and the other one is the mechanical connection provided by the aluminum block and plate.As the service life of existing glass curtain wall grows,the critical boundary connection will produce aging and failure,seriously affecting its safety.Currently there are some research on curtain wall boundary damage identification,but it has not fully considered the actual boundary construction of the hidden frame glass curtain wall,and only studied the damage of the glued boundary and ignore the damage of the mechanical connection boundary;on the other hand,the current damage identification methods often use frequency,vibration type and other indicators.The recognition effect is poor when the degree of damage is small,so that damage identification methods with higher accuracy need to be further studied On the other hand,the current damage identification methods often use frequency and vibration type indicators,which are less effective when the damage is small.In this thesis,based on the modal test of damage identification,we investigate the identification method of various boundary connection damage by combining theoretical calculation and numerical simulation.The main research contents accomplished are as follows:(1)Research on the identification method of the boundary damage of the glued boundary of the hidden frame glass curtain wall.Modal tests were carried out on various sizes of hidden frame glass curtain wall specimens,combined with finite element calculations,to investigate the effects of different gluing boundary damage on the vibration pattern,frequency and other modal parameters of the curtain wall panel,and to analyze the correspondence between the typical boundary conditions of the panel and the degree of gluing boundary damage.The results show that the fundamental frequency and the first-order vibration type of the panel are good for the identification of the degree and location of the gluing damage respectively;the support state of the four sides of the panel when the gluing boundary is intact is comparable to that of the four-sided simple support,while the most serious case of the gluing boundary damage is comparable to that of the two-sided simple support and the two-sided free.According to the above analysis,the damage identification method of two identified glued boundaries is proposed based on the rate of change of fundamental frequency and the analytical solution fundamental frequency threshold,respectively.(2)Research on the damage identification method of mechanical joint boundary of hidden frame glass curtain wall.The damage identification methods of two types of mechanically connected elements,namely aluminum alloy fixed distance pressure block and through-length pressure plate,are studied by means of modal tests,theoretical analysis and numerical simulations,etc.In addition,the effects of various complex damage distributions on panel frequencies and vibration patterns are analyzed by finite elements.The results show that the modal parameters are more sensitive to the damage of the fixed distance pressure block and less effective in identifying the damage of the through-length pressure plate;there is only a small difference between the influence of the modal parameters on the damage of the same degree of pressure block and structural adhesive,and the theory of damage identification of the two has generality,based on which the damage identification method of the mechanical joint boundary based on modal parameters is proposed.(3)Research on the boundary damage identification method of hidden frame glass curtain wall based on curvature mode.Based on the curvature mode of the bridge structure,the curvature mode calculation method applicable to the plate structure is derived,and the effect of curvature mode on the identification of small damage is analyzed by extracting the vibration pattern through finite element analysis;based on this,the average boundary curvature mode change rate is proposed as the damage identification index,and the relationship between it and the degree of integrity of the glued joint boundary is analyzed.The results show that the boundary curvature modal recognition of curtain wall boundary damage is excellent,the same degree of damage,the distribution density of the damage,the location of the damage can be reflected in the average boundary curvature modal rate of change;in addition to the degree of damage,the change in the location of the damage also has a greater impact on the curvature modal;the indicator in the hidden frame glass curtain wall boundary damage recognition species has the feasibility of greatly improving the accuracy of damage recognition.In this thesis,there are 69 figures,6 tables,and 76 references are cited. |
