Xu-Yang Cao

Hohai University · College of Civil and Transportation Engineering

Performance-based earthquake engineering (PBEE) is a popular direction in the earthquake community, and at this stage, risk-based PBEE has become mainstream. In the risk-based probabilistic framework, seismic fragility analysis constitutes the most important link, and corresponding research on the mainshock–aftershock sequence has received widespre...

A resilience-incorporated risk assessment framework is proposed and demonstrated in this study to manifest the advantageous seismic resilience of precast concrete frame (PCF) structures with “dry” connections in terms of their low damage and rapid recovery. The framework integrates various uncertainties in the seismic hazard, fragility, capacity, d...

Carbon fiber reinforced polymer (CFRP) exhibits multiple advantages over conventional steel, such as high strength and corrosion resistance. By replacing prestressing steel with prestressing CFRP in new prestressed reinforced concrete (RC) structures, the corrosion issue of prestressing steel can be resolved. At present, there remains scarce researc...

Performance-based earthquake engineering (PBEE) is essential for ensuring engineering safety. Conducting seismic fragility analysis within this framework is imperative. Existing methods for seismic fragility analysis often rely heavily on double loop reanalysis and empirical data fitting, leading to challenges in obtaining high-precision results wi...

With the development of performance based earthquake engineering, the recognition of performance based seismic design (PBSD) is continuously growing in academia and industry. Meanwhile, with the gradual awareness of earthquake threat to the existing aged buildings, researchers are focusing more on the novel retrofitting technologies to enhance the...

Corrosion of reinforcing bars is an essential explanation for the deterioration of reinforced concrete (RC) members. Consequently, the seismic performance and collapse mechanism of RC members considerably decreased and altered for the sake of corrosion of reinforcing bars, respectively. For evaluating the effect of corrosion of reinforcing bars on...

A consistent seismic hazard and fragility framework considering combined capacity-demand uncertainties is proposed, in light of the probability density evolution method (PDEM). The PDEM has solid theoretical basis in the reliability field, and it is integrated within the performance-based earthquake engineering (PBEE) for hazard-fragility assessment...

Earthquakes cause severe damage to human beings and financial development, and they are commonly associated with a lot of uncertainties and stochastic factors regarding their frequency, intensity and duration. Thus, how to accurately select an earthquake record and determine an earthquake’s influence on structures are important questions that deser...

A probabilistic assessment is performed using different seismic fragility analysis approaches for structures under non-stationary stochastic ground motions. Four commonly used probabilistic seismic fragility analysis (PSFA) approaches are adopted, which are least squares regression (LSR), maximum likelihood estimation (MLE), kernel density estimati...

Seismic retrofitting is a hot issue in the field of earthquake engineering, and the externally-attached substructure approach is a well-known solution due to its no-disturbing construction and high-efficiency improvement. In this paper, a comparative study of a novel externally-attached precast steel-reinforced-concrete (SRC) braced-frames for seis...

To alleviate the consequential influences of earthquakes, many seismic performance evaluation methods have been developed over the past century. Fragility assessment is an effective approach to evaluate the structural response under earthquake excitation, among which the classic parametric linear regression method (LRM) is one of the most popular o...

In this paper, the effectiveness of using newly proposed novel external sub-structures (precast bolt-connected steel-plate reinforced concrete buckling-restrained-brace-frame, PBSPC BRBF) for reducing the collapse as well as post-earthquake demolition risks of old reinforced concrete frames within 20 km near-fault regions is investigated. Two old r...

This present research conducted an experimental study on the influence of different earthquake damages on the seismic performances of aged reinforced concrete (RC) beam-column joints retrofitted with basalt fiber-reinforced polymer (BFRP) sheets under cyclic loadings. Six beam-column joints included one benchmark specimen, one uncorroded specimen r...

In this paper, an enhanced probability density evolution method (PDEM) framework considering multiple failure modes and limit states is proposed for reliability analysis of structures. Firstly, the PDEM principle and the enhanced mechanism are illustrated, and during the process three typical combination types (i.e., circle, triangle, square ways)...

In this paper, a comparison between probability density evolution method (PDEM)-based approach and linear-regression-based approach in seismic fragility assessment is performed, and an application into low-rise frame building is conducted for implementation. The principles of the two fragility approaches are introduced first. The PDEM-based fragili...

With the rapid development of urbanization, the scales of urban population and land use are tremendously expanding [...]

The dynamic and probabilistic seismic performances of precast prestressed reinforced concrete frames (RCFs) are assessed in this paper, and the slab influence in the overall structural behavior is considered during the process. The three-dimensional spatial model is established to provide the numerical basis, and the slab is modelled through L-/T-se...

Earthquakes cause serious damage to buildings and result in heavy losses to society, therefore, it is necessary to enhance the seismic capacity of existing buildings via structural retrofitting. The traditional retrofitting approaches are based on the component-level, but their improvement effect for the overall structure is not obvious. The ultima...

The experimental and theoretical investigations of the existing reinforced concrete frame (RCF) retrofitted with a novel external retrofitting sub-structure, self-centering precast bolt-connected steel-plate reinforced concrete buckling-restrained brace frame (SC-PBSPC BRBF), are presented in this paper. The sub-structure compositions, specimen des...

Reinforcement corrosion and seismic damage considerably affect the seismic performance of reinforced concrete (RC) members. In present research, five RC beam-column joints were designed and tested under cyclic loadings. These joints included one reference specimen, one uncorroded specimen rehabilitated with basalt fiber-reinforced polymer (BFRP) sh...

In this paper, the hysteresis performance of an assembled bolt-connected buckling-restrained brace (AB-BRB) is experimentally discussed by a parametric study, and five changing factors are selected to analyze the corresponding influence in static behaviors. The deformation modes of core plates are compared, the critical points of hysteresis curves...

This paper presents the probabilistic seismic demand and fragility analyses of a novel mid-rise large-span cassette structure. A newly designed nine-storey office building in Hunan, China, is selected, and its two different design schemes, namely, a traditional frame structure and a novel cassette structure, are examined using numerical models esta...

A novel external sub-structure is developed for the seismic performance improvement of existing frame buildings, namely, post-tensioned precast bolt-connected steel-plate reinforced concrete frame (PT-PBSPC frame). The mechanism and design of the sub-structure are introduced, and the pseudo-static experiments are conducted based on 4 scaled frames...

The dynamic and probabilistic seismic performances of precast prestressed RCFs are assessed in this paper, and the slab influence in the overall structural behavior is considered during the process. The threedimensional spatial model is established to provide the numerical basis, and the slab is modelled through L-/T-section beam-slab fiber-section...

Precast reinforced concrete (RC) frames have been rapidly developed in structural engineering due to their various advantages, such as high efficiency and low environmental pollution. However, the construction quality of precast RC frames is difficult to guarantee, and the interface of new and old concrete and the bond-slip effects of additional st...

A new external retrofitting sub-structure is proposed, namely, self-centering precast bolt-connected steel-plate reinforced concrete buckling-restrained-brace-frame (SC-PBSPC BRBF). Based on the 3D numerical model and stiffness-based design method, 5 retrofitting scenarios are performed on a deficient frame building to compare the upgrading effects. Pro...

A new external retrofitting sub-structure is introduced in this paper, namely, precast bolt-connected steel-plate reinforced concrete buckling-restrained-brace-frame (PBSPC BRBF). The numerical model is proposed considering the joint mechanical behavior, postcast concrete effects, and interfacial shear performance, and the results are validated via...

In this paper, the assembled bolt-connected buckling-restrained brace (AB-BRB) with a pair of thin-walled concrete-infilled steel shells (CSS) is experimentally analyzed, centered on the reusing & replacing performance. A total of 8 specimens were well produced according to the proposed design method, and the hysteretic performances were examined u...

A new type of external substructure to upgrade existing reinforced concrete frames (RCFs) is presented in this paper, namely, a self-centering precast bolt-connected steel-plate reinforced concrete buckling-restrained-brace-frame (SC-PBSPC BRBF). The upgrade mechanism and three-dimensional simulation model were analyzed based on relevant experiment...

Precast concrete frame structures are widely adopted around the world due to their various advantages, so it is important to study their seismic performance. The development of damage mechanics has enabled us to accurately investigate the typical failure mechanisms of precast structures. This paper presents three of the most commonly used modeling...

Earthquakes have caused heavy losses to lives and properties in recent years. Seismic strengthening is an important guarantee for improving the structure performance. The ultimate goal of seismic upgrading is to improve the overall seismic performance because the structure is subjected to hazards as a whole. In recent years, a variety of external s...

This paper presents the outside strengthening method of existing frame structures with a precast bolt-connected steel plate reinforced concrete (PBSPC) frame-brace. The working principle and advantages of the PBSPC frame-brace are introduced. To verify the retrofitting effectiveness of the upgrade system, quasi-static tests were conducted for three...

Outside strengthening with precast substructures is a newly arising retrofitting method which is drawing attention of researchers in recent years. Compared with the member-level strengthening technologies (e.g., FRP strengthening, enlarging member section areas and replacing rebars), outside strengthening with precast substructure is a structure-sy...

Precast concrete frame structure is one of the most widely used precast structural systems. The crucial part of this kind of structures is the beam-to-column connection, which not only affects the global seismic performance, but also related to the overall feasibility and the economical efficiency in construction. According to the mechanism of diff...