Increasing numbers of complex structures are being constructed with the acceleration of urbanization. The complex dynamic characteristics pose challenges to the seismic design of large chassis. This paper investigates the seismic response and damage evolution of complex structures using linear and nonlinear dynamic explicit analysis under obliquely incident SV waves. A twodimensional finite element model considering soil-structure interaction (SSI) is developed using fiber beam elements. Elastic and elastoplastic damage constitutive models are employed. A comprehensive numerical analysis is conducted to investigate the influence of key parameters, including incidence angles, ground motion characteristics, and site types, on the seismic response and damage evolution of complex structures. The results of this study indicate that, in the elastic stage, the seismic response of the frame-shear wall structure is reduced in the case of oblique incidence compared to vertical incidence. Specifically, the inter-story drift ratio is reduced by 60% at an incidence angle of 30 degrees. In comparison to vertical incidence, the inter-story drift ratio and horizontal acceleration of the underground structure are reduced under oblique incidence. Conversely, in the elastic stage, the beam-end vertical displacement ratio and vertical acceleration exhibit increases of 57% and 36%, respectively. In the elastoplastic stage, as the incidence angle increases, the damage to the beams of the underground structure becomes more significant, while the damage to the frame-shear wall structure relatively decreases. Low-frequency ground motion and soft soil amplify the structural response compared to high-frequency and hard soil.

In order to further study the dynamic response and damage status of the subway station structure and promote the development of the TOD (transit-oriented development) mode structure system, this paper proposes a calibration method for the seismic performance index limit of the subway station complex structure in TOD mode. Taking a practical project in the Beijing city sub-center station integrated transport hub as the research background, the nonlinear analysis model of soil-structure interaction under different site types is established. Firstly, the limit value of the interstory drift ratio is determined by the pushover loading method of the inverted triangular distributed load for the three-dimensional numerical model. Secondly, different types of seismic waves are selected to analyze the seismic vulnerability of the simplified two-dimensional numerical model, and the exceedance probability of different damage states of the structure is quantitatively analyzed. By analyzing the pushover curve, the maximum interstory drift ratio limits corresponding to the five damage states of the subway station complex structure are 0.14%, 0.32%, 0.66%, and 1.12%, respectively. Under different site types and different types of seismic waves, the seismic response law of subway station structures in TOD mode is different. Using different types of ground motion as the input, the mean and discreteness of different IDA curve clusters are quite different. The near-field pulse-type ground motion has a greater impact on the ground motion of the structural system under the Class II site, and the far-field long-period ground motion has a greater impact on the structure under the Class III site. Damage decreases with the increase in the equivalent shear wave velocity of the site, that is, the harder the site's soil is, the less susceptible the structural system is to damage by underground motion. The established seismic vulnerability curve and seismic damage probability table can effectively evaluate the seismic performance of subway station complex structure in TOD mode. The research results can provide a valuable reference for the seismic performance evaluation of similar underground structures.

The paper presents a study on the dredging vibrational effects, for nourishment purpose, on the existing structures surrounding the worksite. Nourishment is a common operation when beach (or coasts, or ports) protection is required, allowing to reduce far-field impacts of coastal structures and improve navigability. Nourishment is then performed to reshape underwater land, and it is usually practiced by locating in the zones in which is required, soil coming from nearby areas. This latter is often obtained by a dredging process, in which the phases of excavation, transportation and soil placement are carried out. From the structural point of view, of interest is the excavation phase, which is usually performed in the water environment by a ship equipped with a dredge that mines the seabed, generating a new source of vibrations for the existing structures facing the working area. The aim of this paper is to assess the effects of vibrations induced by dredging operations, by taking as reference the recently performed nourishment in the port of Bari, Southern Italy. To this scope, an existing structure was selected and identified as sentry building, considering its extreme proximity to the worksite. Hence, a structural monitoring was performed, by investigating the behaviour of the structure before, during and after the dredging. Three main controls were carried out within the monitoring campaign: (a) check of the vibration levels and comparison with thresholds provided by the current Italian prescriptions for human comfort and structural damages; (b) operational modal analysis to assess the possible variations of the structural behaviour during dredging; (c) calibration of a numerical model to simulate the structural behaviour of the sentry building and to derive unknown geometrical and mechanical parameters. A full description of the reference building (characterized by a certain irregularity degree) and all the monitoring phases are reported throughout the manuscript. The results show that, over the monitoring period, the dredging vibration levels never exceeded the thresholds provided by code provisions, and subsequently, the sentry building did not report structural damages, as confirmed by the continuous control of dynamic parameters from experimental and numerical models. In addition, the contents of the paper show the paramount importance of the structural health monitoring, and the experience herein reported can inspire the management of buildings under particular actions like the ones herein investigated.