Failure Detection Of The Glass Panel And Safety Evaluation Of Glass Curtain Wall

Glass curtain wall is widely used in high building, and becomes one of the most important parts of modern structures. With the increase of total amounts and service life, spontaneous breakage or falling down of curtain wall glass in service have been frequently reported, and resulted in a lot chaos, causing economic loss or even serious disaster. Therefore, the methods of damages detection, risk prediction and safety evaluation of a curtain-wall system, have attracted great attention of materials scientist and structure engineer. Furthermore, it is also urgent to ensure the safety of glass curtain wall and to prevent calamitous accident.Failure of structure and materials may influence the safety performance of the curtain wall glass seriously, and the failure in the function of the curtain wall glass may accelerate structure and materials failure. In this work, therefore, the focuses are put on the on-site detection technique of structure failure under different support systems, and function failure of the glass in the glass curtain wall. The primary research works and obtained results are as follows:(1) A vibration method is proposed to predict the loosening extent of the support structure and aging extent of the structure sealant based the natural frequency changes of the curtain wall glass. A relationship between the frequency changes and the reliability of the glass curtain wall with various supports were established by experiment. The results indicate that there exist an upper limit and lower limit for the measured natural frequencies of a glass fixed at four sides. The upper lower limit is about 20% higher than the frequency of the simply supported plate with the same size, and the upper limit is nearly 20% below that of the clamped supported plate. Aging tests of the structure sealant in concealed frame glass curtain wall exhibit an interesting phenomenon that the natural frequencies of the glass declined with the increasing aging time. Based on the obtained results, an evaluation criterion was developed to evaluate the reliability of the glass curtain wall via the changes of the measured frequency. Since frequency measurements can be cheaply acquired, the approach could provide an inexpensive assessment technique for glass curtain wall.(2) The quality problems of insulating layer failure and outer panel fall down of the insulating glazing have attracted great attention from us. In this thesis, based on the ideal gas equation and the quantity of volume changes in the insulating gas layer, the deformation and stresses distribute in the insulating glazing due to wind load, ambient temperature and pressure difference were calculated quantitatively. Thus, the quantitative calculation of deformation and stresses in the insulating glazing due to ambient temperature and pressure difference were realized. It also provides an approach for safety application, failure detection and checking the bearing capacity of the insulating glazing. Because the stiffness of the insulating glazing is changed after the failure of insulating layer, accordingly, a detection method is proposed by measuring the deflection of the inner and outer glass panels or the distance between both panels under given a concentration load at the central of the glass pane to identify the sealing performance of insulating glass.(3) In order to meet the needs of development and application of the vacuum glazing, strength theories and optimization design of the vacuum glazing were studied. Based on the structural characteristics of the vacuum glazing, the mechanical models were established and the stresses distribution in the vacuum glazing caused by atmospheric pressure was calculated. The strength behavior of the vacuum glazing and influencing factors were investigated by using uniform load test on the glass plate. The calculation formula of the resistance to wind load and strength design factors of the glass were given. Furthermore, the photo-elastic method and dynamic method were put forward to detect the vacuum degree of the vacuum glazing. It was discovered the photoelasticity figure and natural frequency of the plate depend on the vacuum degree of the vacuum glazing.