Tornado-affected safety assessment of tower cranes outer-attached to super high-rise buildings in construction

Abstract

To fully address the safety concern of construction tower cranes outer-attached to super high-rise buildings in tornado wind fields, the safety envelopes of cranes under various scenarios are constructed. To more precisely obtain the time history of wind forces applied on the building-crane system in a tornado environment, the working conditions of cranes and the feature of the tornado field are considered in the development of various spatio-temporal computational fluid dynamics (CFD) models. To avoid sophisticated finite element analysis of the main building, the modified generalized flexural-shear model (FSM-MS) is used to estimate the along-wind and across-wind displacement response of main building and the response at the connection support of the tower crane. To reproduce possible failure modes of tower cranes as many as possible, the similar concept of incremental dynamic analysis was adopted to generate the safety envelopes of outer-attached tower cranes in various normal and typical abnormal scenarios. By this, whether a tower crane of concern is safe or not can be efficiently assessed by the ultimate wind velocity obtained from the envelope corresponding to certain working conditions. The feasibility of the safety assessment procedure has been systematically demonstrated on three case super high-rise buildings. The ultimate reference wind velocity of the tower crane was observed to be more sensitive to slewing angle. And, more attention should be paid to the issues of overloading and stiffness reduction of connection supports. The outcome from this concern has definitely enriched the framework of construction safety control management.