Numerical Study on Toppling Mechanisms of Crane and Pile Driver Based on Structural Stability Theory

Abstract

This paper presents a numerical investigation into the theoretical safety criteria for the toppling of cranes and pile drivers by providing sample calculations and expanding on previously published theoretical work, in which the fundamental elements, such as the structural model, the classification of toppling modes, etc., are developed. It is believed that the frequent occurrences of crane and pile driver toppling are closely related to structural instability within their toppling mechanisms. The conventional evaluation method for toppling stability, which is based on the overturning moment approach, may not sufficiently address the mechanisms of toppling on soft ground. In fact, many toppling accidents show signs of inadequate ground strength, such as ground failure. This issue likely involves not only a lack of ground strength to withstand the bearing pressure from crawlers or outriggers but also insufficient deformation performance (stiffness) of the ground. In structural stability theory, an important factor in assessing the required ground stiffness is the height of the applied load. Conventional toppling stability assessments assume that if the overturning moment is the same, the stability will also be the same. However, from the perspective of structural stability theory, toppling can occur even when the overturning moment is zero in extreme cases with weak ground stiffness and large load height. This study aims to look for the influence on the toppling mechanism by presenting sample calculations for a simple analytical model under various operational conditions—including load height, ground stiffness, and working radius—to better define the criteria for toppling.

Received: 14 May 2025 | Revised: 17 July 2025 | Accepted: 9 September 2025

Conflicts of Interest

The authors declare that they have no conflicts of interest to this work.

Data Availability Statement

Data are available from the corresponding author upon reasonable request.

Author Contribution Statement

Shouji Toma: Conceptualization, Methodology, Formal analysis, Investigation, Data curation, Writing - original draft, Writing - review & editing, Visualization. Wai Fah Chen: Validation, Supervision, Project administration.