Bridge structures are the important part of lifeline engineering, which are easy to lose their traffic function when subjected to strong earthquakes. Seismic resilient bridge structures are that do not require repair or can be restored to normal operating condition with minor repair after an earthquake, which are mainly characterized by self-centering capacity, damage control capacity and easy repair. Therefore, the bridge structures with seismic resilience have become one of the research hotspots in bridge engineering due to the excellent characteristics. This paper firstly reviews the development of bridge seismic design theory, and then highlights the current status of research on bridge structures with seismic resilience. The seismic resilient bridge structures are divided into rocking bridges, bridges with replaceable members and bridges with high-performance materials, according to the method to achieve the performance recovery of bridge structures. Then the research status of these three kinds of seismic resilient bridge structures is reviewed and summarized systematically. A large number of experimental studies and numerical simulations have presented that the seismic resilient bridge structures have excellent performance recovery capability. In addition, this paper also summarizes the current research status of performance evaluation and design methods of seismic resilient bridge structures, and presents practical engineering applications of typical seismic resilient bridge structures. Finally, the future research directions and development trends of seismic resilient bridge structures are prospected.
Shear keys as sacrificial components are widely used in cap beams and abutments of highway bridges to limit the transverse displacement of superstructures and avoid damage of substructures. To investigate the seismic capacity of bridge exterior shear keys, six exterior shear key specimens were designed on the basis of current Chinese seismic design guidelines of highway bridges and subsequently tested under monotonic lateral loading. The influence of vertical and horizontal reinforcement ratios on the seismic capacity of the bridge shear keys was studied. Two typical failure modes of the exterior shear key specimens, diagonal tension failure and sliding shear failure, were observed during the tests. The reinforcement ratios of the shear key and cap beam have significant influence on the seismic capacity of exterior shear keys. Moreover, different analytical models corresponding to the two failure modes were developed to predict the seismic capacity of the shear key specimens in this paper. Compared with the experimental results, the two analytical models proposed in this study can better predict the load-carrying capacity of the shear key specimens than the classical analytical models.
Rocking philosophy has advantages to maintain a preferable post-earthquake serviceability as an alternative of seismic resistant systems. This article presents an experimental study on the seismic behavior of a rocking bridge with freestanding columns capped with a freely supported deck. A 1/10 scaled, single-span double-column freestanding bridge was constructed and tested on a shaking table. The experimental results showed that the bridge model could undergo large rocking with enough stability under earthquakes and presented excellent post-earthquake resilience after earthquakes with limited damage and negligible residual displacement. The rocking bridge model also exhibited expected isolation efficiency, which increases as the level of excitations becomes more severe. In addition, an analytical model based on multi-block rocking mechanisms was used to calculate the displacement response. Compared with the experimental results, this analytical model well predicts the peak displacement of the rocking bridge model.
Aging, corrosive environments, and inadequate maintenance may result in performance deterioration of civil infrastructures, and finite element model updating is a commonly employed structural health monitoring procedure in civil engineering to reflect the current situation and to ensure the safety and serviceability of structures. Using the finite element model updating process to obtain the relationship between the structural responses and updating parameters, this paper proposes a method of using the wavelet neural network (WNN) as the surrogate model combined with the wind-driven optimization (WDO) algorithm to update the structural finite element model. The method was applied to finite element model updating of a continuous beam structure of three equal spans to verify its feasibility, the results show that the WNN can reflect the nonlinear relationship between structural responses and the parameters and has an outstanding simulation performance; the WDO has an excellent ability for optimization and can effectively improve the efficiency of model updating. Finally, the method was applied to update a real bridge model, and the results show that the finite element model update based on WDO and WNN is applicable to the updating of a multi-parameter bridge model, which has practical significance in engineering and high efficiency in finite element model updating. The differences between the updated values and measured values are all within the range of 5%, while the maximum difference was reduced from −10.9% to −3.6%. The proposed finite element model updating method is applicable and practical for multi-parameter bridge model updating and has the advantages of high updating efficiency, reliability, and practical significance.
The “321” prefabricated highway steel truss bridge is widely used for highway rescue, disaster relief, and emergency traffic. This paper uses a 33 m double-row monolayer “321” prefabricated highway steel truss bridge to analyze its mechanical properties and component stability. The actual traffic flow capacity of a total weight of 53.32 tons is used in this study. The results show that the maximum internal force in the truss chord (including the stiffening chord) occurs in the middle span section when a centrally distributed load is applied. Meanwhile, the maximum internal force of truss diagonal members and truss vertical bars appears at the fulcrum section. Under the eccentrically distributed load, the maximum internal forces of truss chords (including stiffening chords) appear in the middle span section, which is closest to the vehicle load, while the maximum internal forces of truss diagonal members and truss vertical bars appear in the fulcrum section, which is closest to the vehicle load. While the maximum internal forces under the eccentrically distributed load are greater than the maximum internal forces under the centered-layout load, under the vehicle load, truss chords (including stiffening chords) are prone to buckling instability, and the buckling mode is mainly reverse out-of-plane buckling. The inclined members of the truss are prone to buckling instability, and the buckling mode is mainly the combination of out-of-plane bending and two-way out-of-plane bending. Truss vertical bars have good stability and are not easy to buckle. The main conclusions of this paper can provide references for the optimal design and operation safety of prefabricated highway steel truss bridges.