Correlation Analysis of the Key Factors of Facade Shedding of Buildings

In recent years， the casualty accidents caused by the facade shedding become obvisouly more frequent， making the building operation and maintenance safety issues obtain wide attention. Therefore， ensuring the safety and reliability of building facades as well as prolonging their service life have become one of the most primary tasks during the operation and maintenance phase of existing buildings. In order to investigate the main factors of the building facade shedding and clarify the relations between each other， 1030 cases of external wall shedding across the country since 2000 were collected， and nine essential factors were sorted out including material types， duration of use， seasons， geographical regions， loss types， shedding areas， shedding heights， wind forces and temperatures. The frequency analysis method was employed to reveal interaction patterns among these factors， while independence tests and Pearson analysis were conducted to explore the degree of mutual correlation. It was found that average service life of external insulation layers， tiles， coatings， and exterior-mounted material in the statistical cases reached 1.47 years，5.26 years， 3.30 years， and 2.49 years， respectively， which were evidently less than the age limit in Technical Standard for External Thermal Insulation on Walls（JGJ 144-2019）. Shedding areas were pre-dominantly concentrated within the range of 0.72 m² to 49.50 m²， indicating a tendency for collective shedding mode of facade materials. The shedding area demonstrated correlations with material types， regions and duration of use， and the loss was also related to the shedding area and the duration of use. The heights and types of detachment correlated with wind forces， which was further associated with seasons， regions， the area of detachment， and temperatures. Additionally， temperatures exhibited a correlation with regional characteristics. In particular， the correlation degrees between the shedding area and the duration of use， between shedding area and material types， between the shedding height and types， as well as between the wind force and the area were the highest， the correlation coefficients reached -0.22， -0.22， -0.27 and -0.23， respectively， indicating that the small area of shedding was significantly influenced by the duration of use； in comparison to coatings， tiles， and exterior-mounted material utilized in building finish layers， the exterior insulation layers were more susceptible to produce large-scale shedding. The correlation between the external insulation layer and the height of shedding was noticeable， and the external insulation layer was more likely to be affected by the height than other external wall materials. The exterior walls in Northeast and North China are more susceptible to strong winds， which may increase the risk of shedding.