## 1 Introduction  
In recent years, there has been a boom in the research of Very Large Floating Structure (VLFS) in the international marine engineering community. Based on national conditions, China has also started a series of concept proofs for mega-floating structures [1], and numerous scholars have made various research results in this field. A floating airport at sea is a specific application of super-large floating structures, which can be used as a maritime supply base for aircraft to enhance their range and play an important strategic role in maintaining the sovereignty of our territorial waters from infringement. However, the most significant feature of floating airports at sea is the huge size of the structure compared to conventional floating platforms at sea [2]. The huge aspect ratio makes the mega-float an extremely flat and flexible structure at sea, whose elastic deformation is often of the same order of magnitude as the rigid body displacement [3]. The dynamic response of oversized floating bodies in complex marine environments exhibits significant nonlinearity and often requires consideration of the coupling between the fluid and the floating body, so it is particularly important to carry out research on the nonlinear dynamic response characteristics of oversized floating bodies in offshore airports under wind and wave environments. For the floating airport model at sea, the initial study was to reduce it to a plate and beam model [4; 5]; due to its huge scale, the modular structure design is a natural choice [6]. In order to reduce the wave action on large structures, semi-submersible floating modules are used, and simplified calculations usually treat such modules as rigid bodies [7]. With the rise of hydroelasticity theory [8] in the late 1970s, numerous scholars have started to analyze its hydroelastic response characteristics [9; 10]. Hydroelasticity not only summarizes all the dynamical problems in each of the two fields of structure and fluid, but also includes the coupling problems between them [11]. Among them, [PERSON] [12] considered the structural elastic deformation in the calculation of the radiative velocity potential and concluded that the hydroelastic response of the floating body is affected by three components, namely, the incident velocity potential, the bypassing velocity potential generated around the floating body, and the radiative velocity potential generated by the motion and deformation of the floating body itself on the flow field. The current analysis of the dynamic response characteristics of offshore oversized floating structures is mostly limited to under regular waves. [PERSON] et al. [13] were able to accurately calculate the structural deformation and stress distribution of the floating body under regular waves. [PERSON] et al. [14; 15] used linear wave theory and classical thin-plate theory to carry out simplified hydroelastic analysis of VLFS under regular waves, and confirmed the feasibility of the method through experiments. Under irregular waves, [PERSON] et al. [16] established a simplified calculation method and corresponding calculation software for the hydroelastic response of each module of VLFS under irregular waves. [PERSON], [PERSON] [17] et al. modeled the dynamics of non-regular wave networks and established wave pools for experimental and numerical validation. If only the dynamic response characteristics of the floating body under regular and irregular waves at a specific frequency are analyzed, it is obviously not in line with the actual situation. During the actual operation of the floating body, it will encounter the influence of incident waves in different wave directions. [PERSON] et al. [3] carried out the analysis of the elastic response of oversized floating bodies under different wave angles of regular wave action, however, the analysis of the dynamic response of offshore airports under different wave angles of non-regular waves should not be neglected.