# Experimental and Numerical Study of the Jib Connection Frame of a Wheeled Crane
## 1 Introduction  
The continuous development of society has led to an increased reliance on cranes in a variety of contexts. From the construction industry to the petrochemical sector, cranes have become indispensable construction machines. Among the numerous types of cranes, wheeled cranes are particularly flexible, high-speed, and can be transferred quickly, making them well suited to workplaces with large mobility and instability. The boom is the primary bearing component of a crane, and its bearing capacity directly determines the crane's lifting performance. The truss boom is a lattice structure with a low self-weight and a high bearing capacity. However, because the boom is generally used at certain heights, as shown in Figure 1, safety is an issue of paramount importance. Ensuring the overall stability and local stability of the truss boom has become a key research issue. The connecting frame, which connects the jib and the main boom, transfers the force of the jib to the main boom. The connecting frame serves as a transitional element, and thus the stability of this component is crucial. The main arm and the jib are connected through the connecting joint, which is subjected to tensile and compressive loads simultaneously during operation, and as a load transferhub, the instability problem caused by local damage will be particularly serious. Existing research on the overall stability of the lifting arm is relatively extensive, but there is a lack of in-depth research on the mechanical behavior of the connecting frame, which is a key transition component. To avoid the risk of local damage, it is necessary to study the connecting frame, which also provides a new entry point for studying the stability of similar short-arm structures. Currently, the research methods for stability problems are mainly divided into two categories: computational analysis and experimental verification. The computational methods can be further subdivided into canonical [1; 2; 3; 4; 5], theoretical analysis [6; 7; 8; 9], and finite element analysis methods [10; 11; 12; 13]. Among them, the canonical method is widely used, but there are some limitations when dealing with complex and variable structural forms; the theoretical analysis method is still at the stage of continuous exploration, for example, the accurate finite element method proposed by Prof. [PERSON] of Harbin Institute of Technology based on second-order theory [14; 15]. Although this method has been used to analyze the typical structure of cranes and other typical structures effectively, the relevant theoretical model often relies on idealized assumptions, and it is difficult to fully reflect nonlinear behavior in actual engineering. In contrast, finite element analysis is currently the most commonly used method due to its ability to accurately simulate complex geometry and material properties. However, the computational efficiency of this method needs to be improved when dealing with large-scale complex structures. [PERSON] et al. [16] derived theoretical formulations and carried out Ansys analysis for three-dimensional structures. [PERSON] et al. [17] dealt with the overall stability in truss optimization by introducing semidefinite constraints and analyzed the local stability by combining with Eulerian critical buckling loads. [PERSON] et al. [18] converted the truss layout optimization problem with overall stability constraints into a linear semidefinite programming problem. [PERSON] et al. [19] optimized the structural parameters of crane outriggers using the finite element method. However, most of the existing studies focus on independent components, such as outriggers and main booms, and there are still deficiencies in the cooperative force analysis of such subassemblies as connecting frames. Since the theoretical analysis methods are still at the continuous exploration stage, some theoretical models provide insufficient accuracy when dealing with nonlinear factors and complex boundary conditions in actual structures.