A Study on Safety Criteria for Toppling of Pile Drivers and Cranes Based on Structural Stability

Abstract

The toppling mechanisms of heavy machinery with high center of gravity such as pile drivers, cranes, jacks, etc., can be broadly classified into two categories: overturning moment toppling and structural instability toppling. The structural instability toppling is further divided into buckling toppling and equilibrium transition toppling. These three toppling mechanisms are significantly different, and it is necessary to address their safety separately when discussing safety criteria. Therefore, it is considered that safety criteria should be established coping with characteristics of each toppling mechanism. In particular, toppling in the case of structural instability has not had clear safety criteria so far, and the development of rational safety criteria based on structural stability theory is considered important to prevent future toppling accidents. This paper provides a sample of the safety criteria that align with the classification of the three toppling mechanisms. For the buckling toppling, the criterion is set to restrict the vertical load considering the critical load (buckling). For the overturning moment toppling, the criterion is set to restrict the inclination angle in order not to exceed the stability limit angle. Additionally, for the equilibrium transition toppling, the criterion is set on both the vertical load and the inclination angle so that the maximum displacement angle due to dynamic inertial force does not exceed the stability limit angle. A sample of the safety criteria provided in this paper includes the three toppling mechanisms which should be covered to avoid the toppling accidents of heavy machinery which has high center of gravity.