Abstract
In the last century, a modern seismic design concept has emerged, which is based on different mechanisms, such as reducing and dispersing the seismic input concerning the building or active ...interaction with the movement of the building. From the past to the present, a wide variety of seismic control methods have been found and applied, together with the modern understanding of seismic design. Using seismic control in buildings increases the functionality of the building and prevents extra structural requirements. This philosophy constitutes an alternative to the conventional seismic design approach, which relies on consuming earthquake energy on its own. With the changing approach, the concepts of seismic design philosophy have changed, and architectural design has been affected from many points by these concepts. Therefore, architects/designers should examine how the decision to use seismic control methods that concern building design decisions from the preliminary design phase will affect the architecture. This study, starting from the historical development of base isolation and energy damping systems, which are widely used among seismic control methods, focuses on new buildings, and new concepts emerging with the modern seismic design approach and their effects on architectural design are discussed in detail. The study’s methodology involves evaluating data from existing literature works, building codes, professionals, and practices. As a result, the architectural design of new buildings in the context of base isolation and energy-damping systems is evaluated in terms of the seismic device–building form relationship, planning and location, architectural details, aesthetics, and user comfort, and knowledge and recommendations are presented to architects/professionals.
•A method for Performance-Based Seismic Design (PBSD) of low-rise structures with BRBs is proposed.•The method assumes that structures equipped with BRBs behave as dual systems.•It generates ...information useful for preliminary performance assessment of the structure.•Therefore, it allows the rapid application of PBSD philosophy in low-rise buildings.•An example of application is provided to show the applicability of the proposed method.
This paper proposes a method for preliminary Performance-Based Seismic Design (PBSD) of low-rise structures protected with Buckling-Restrained Braces (BRBs). It is assumed that a frame structure protected with BRBs, termed as a dual structure, is rationally represented by a dual single-degree-of-freedom (SDOF) oscillator whose parts yield at different displacement levels. The formulation of the method is presented for SDOF structures. This simplification is validated using a case study example. A comparison of the responses between conventional and dual structures shows that, when designing dual structures, the common practice of using conventional design spectra may lead to biased designs. One of the main advantages of the method is that, during its application, information useful for preliminary and quick assessment of structures is generated, facilitating the application of the PBSD philosophy. A case study example is conducted to show its applicability and its potential for preliminary assessment of structures. Regarding its limitations, the method is valid for low-rise regular buildings with rigid in-plane diaphragms, and whose dynamic response is dominated by their fundamental mode of vibration.
Many recent research studies focused on the development of innovative seismic resilient structures by chasing the objectives of minimising both seismic damage and repair time, hence allowing the ...definition of structures able to go back to the undamaged, fully functional condition, in a short time. In this context, the present study investigates an innovative type of self-centring damage-free steel column base (CB) connection and its beneficial effects when used within steel moment-resisting frames (MRFs). The proposed connection consists of a rocking column equipped with a combination of friction devices, providing energy dissipation capacity, and post-tensioned bars with disk springs, introducing restoring forces in the joint. Contrary to conventional steel CBs, the proposed connection exhibits moment–rotation behaviours that can be described by simple analytical equations, allowing the definition of an easy-to-apply design procedure. Numerical models of the connection, developed in OpenSees, are validated against experimental results and successively implemented within a four-storey case study steel MRF. Incremental Dynamic Analyses are performed to derive the samples of the demand for the engineering demand parameters of interest while accounting for the record-to-record variability. Fragility Curves show the effectiveness of the proposed solution in reducing the residual storey drifts and in protecting the first-storey columns from damage, hence providing significant advantages in terms of repairability, and hence resilience of the structure with a negligible increase on the overall cost. The results show that the damage-free behaviour of the CBs is a key requirement when self-centring of MRFs is a design objective.
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•Innovative type of self-centring damage-free steel column base connection.•Analytical Design procedure for moment-rotation response of the connection.•Validated OpenSees model of the column base against experimental results.•Incremental Dynamic Analyses and Fragility Curves.•Enhanced structural resilience through localised self-centring systems.
•An optimal design procedure is developed for the damper devices in cable-stayed bridge.•The genetic algorithm is implemented in optimization based on parallel computation.•The optimal design ...parameters lead to significant reduction of overall repair cost.
The seismic vulnerability of cable-stayed bridges located in seismically active regions can be of great concern to the regional safety and resilience. A promising design practice for cable-stayed bridges lies in decoupling the deck from deck-pylon connection and incorporating energy dissipation devices to reduce the dynamic responses. In this study, the performance-based seismic design (PBSD) procedure is adapted to the optimal design of damper devices at the deck-pylon connections in a benchmark cable-stayed bridge. The benchmark cable-stayed bridge was modeled in the OpenSees platform, which was calibrated against the previous finite element models. Then it was seismically designed with viscous and metallic dampers in the longitudinal and transverse direction, respectively. The component-level fragility functions of the cable-stayed bridge were first derived based upon the multiple stripe analysis (MSA) method, and then the system-level repair cost ratio (RCR) surfaces were built under the PBSD framework. Finally, the genetic algorithm based on parallel computation was utilized to identify the optimal parameters of the damper devices. The analysis results illustrate that the optimal design parameters can be effectively obtained through the proposed method, and the damper devices with optimal parameters lead to a significant reduction of the overall repair cost. The study also demonstrates that if the device parameters are not selected appropriately, the dampers can have negative effects on bridge responses. The design framework and the findings could provide the guidance for the designing and retrofitting of cable-stayed bridges in practice.
Abnormal events, that are unforeseeable low-probability and high-impact events, cause local failure(s) to structures that can lead to the collapse of other members and, eventually, to a ...disproportionate progressive collapse. Ordinary design procedures, which are usually limited to gravity and seismic/wind loads, are inadequate for preventing the progressive collapse. Therefore, a focus on strengthening and retrofitting techniques to mitigate progressive collapse is necessary. Parameters such as topology of the structure, nature of the triggering event, size of the initial failure, typology of the collapse and seismic design requirements affect the strengthening and retrofitting strategy. A discussion on the impact of these parameters on strengthening strategy is first presented. Then, a comprehensive review on strengthening and retrofitting techniques to mitigate progressive collapse is provided. The paper concludes with an ambitious comprehensive list of issues covering different aspects of future research agenda.
•Effects of collapse typology and structural topology on strengthening schemes.•Interactions between seismic and progressive collapse design.•Unwanted effects of strengthening and retrofitting strategies.•Categorization and deep discussion on strengthening and retrofitting techniques.•An ambitious comprehensive list of future research agenda.
AbstractIn this research, a low-damage seismic design technology has been proposed for accelerated bridge construction (ABC). ABC low damage aims to minimize, and potentially eliminate, damage in a ...precast bridge during an earthquake. The low-damage design uses dissipative controlled rocking (DCR) connections between the precast elements in a bridge substructure. A DCR connection replaces the traditional plastic hinge at the column-to-footing or column-to-cap beam locations. DCR combines unbonded post-tensioning and externally attached metallic dissipaters to provide self-centering and energy absorption capabilities for the bridge, respectively. In this research, a half-scale precast bent was tested under quasi-static cyclic loading to validate the concept of low-damage design. The performance of the bent was compared against an equivalent bent with emulative cast-in-place connections. Results from testing suggested high performance of the low-damage bent. Following many cycles of large drift ratios, there was no damage or residual displacement in the bent. Findings from this research were implemented in the Wigram-Magdala Link Bridge in Christchurch, New Zealand, in July 2016. The bridge remained intact during the Kaikoura Earthquake on November 14, 2016.
Modern seismic design and construction technologies have undergone significant developments over the last 100 years. In order to prevent collapse of buildings under large earthquakes while ...maintaining reasonable construction costs, structures are allowed to undergo ductile plastic deformations under current design and detailing methods. This implies that large numbers of buildings may be significantly damaged and not only individual buildings but also entire cities may lose their function following extreme earthquake events. In recent large earthquakes, it has been observed that many properly designed and constructed buildings, which did not collapse, were no longer functional and were later demolished rather than being repaired. Considering such situations, the earthquake-resistant design philosophy developed in the previous century should now be revised to meet modern social and economic requirements and Sustainable Development Goals (“SDGs”). The seismic design philosophy for building and infrastructure should be changed from life-saving to business continuity for modern and resilient societies. Structures should be designed to be quickly restored to full operation with minimal disruption and cost following a large earthquake.
•Structures have been designed to undergo ductile plastic deformations in case of large earthquakes.•Large numbers of buildings may be significantly damaged and not only individual buildings but also entire cities may lose their function following extreme earthquake events.•The earthquake-resistant design philosophy should now be revised to meet modern social and economic requirements and Sustainable Development Goals (“SDGs”).•The seismic design philosophy for building and infrastructure should be changed from life-saving to business continuity for modern and resilient societies.•Structures should be designed to be quickly restored to full operation with minimal disruption and cost following a large earthquake.
AbstractThis paper presents an analysis–redesign-type approach for the efficient seismic design of three-dimensional (3D) irregular RC frame structures for bidirectional ground motions. The designs ...obtained using the approach satisfy interstory drift and ductility limits while having the minimum total moment capacity of all seismic members. This leads to cost-efficient designs because the total amount of steel as well as the base shear and overturning moments are relatively low. While doing that, the approach is very intuitive and is relatively simple to implement in practice because it only requires analysis tools, not background knowledge or tools related to optimization theory. The examples show that the proposed methodology requires only a few analyses and converges to designs that exactly satisfy the design objectives with limited amounts of steel assigned only where required. This makes the design approach feasible for practice in terms of computational effort and time.
A two-level performance-based seismic design (PBSD) approach for frame structures isolated by self-centring isolators (SCIs) is proposed in this study. Unlike the traditional PBSD process that ...generally designs a structure for a specific seismic intensity level first and then checks structural performance for other levels, the proposed PBSD approach considers both the design basis earthquakes (DBE) and maximum considered earthquakes (MCE) by analysing two different nonlinear equivalent structural models, thereby enabling the accurate control of structural performance objectives at two different seismic intensity levels during the design process. The design method combines the fundamental displacement-based design process and the widely-accepted nonlinear response spectra. A four-storey frame structure, equipped with novel SCIs consisting of rubber bearing, steel U-shaped dampers, and shape memory alloy U-shaped dampers, is designed as an example. Seismic analysis results demonstrate that the two-level PBSD approach can satisfactorily achieve the predefined performance objectives at both DBE and MCE levels. Although the design process is applied to SCI-isolated structures in this study, the design framework can be easily extended to other types of isolated structures to enable the advanced design that can achieve the target performances at DBE and MCE levels simultaneously.
•A PBSD approach considering both DBE and MCE design objectives is proposed.•Structural performance under DBE and MCE can be controlled without design iterations.•A steel frame with novel SCIs was designed to examine the efficiency of the PBSD approach.•The design approach can be easily extended to other types of framed structures.
•The probabilistic peak and residual displacement prediction models for the enhanced BRBF with the consideration of isotropic hardening are developed using ANN.•A software was developed based on the ...ANN models for predicting the probabilistic peak and residual displacement responses of the enhanced BRBF.•A probabilistic residual displacement-based design method for improving the post-earthquake repairability of BRBF using self-centering braces is proposed.•The RBRBF designed with the proposed design method can achieve the desired residual displacement responses under earthquakes.•The designed RBRBF can provide continuous service without repair with a probability of 96% after MCE excitations.
Buckling-restrained braces (BRBs) can effectively control the structural maximum displacements. However, their full hysteresis tends to cause significant residual drifts after strong earthquakes, resulting in massive economic loss. To improve the resilience of the buckling-restrained braced frames (BRBFs) by reducing the residual drifts, self-centering braces (SCBs) are introduced to BRBFs based on the probabilistic residual displacement-based design (PRDBD) method in this study. Parametric analyses are first carried out on single-degree-of-freedom (SDOF) systems to represent the retrofitted BRBFs subjected to near-fault pulse-like earthquakes, wherein the isotropic strain hardening of BRBs is considered. The probabilistic prediction models for maximum and residual displacement are subsequently developed by employing an artificial neural network (ANN) machine learning algorithm. Subsequently, the PRDBD method is proposed. A benchmark BRBF is retrofitted by SCBs to demonstrate the PRDBD’s effectiveness. System-level nonlinear time-history analyses (THAs) are performed to study the dynamic performance of the enhanced BRBFs. It can be observed from the analysis results that the proposed PRDBD is efficient in controlling residual displacements of the enhanced BRBFs within the prescribed guarantee rate. Moreover, the analysis results confirm that the retrofitted BRBF with partial self-centering behavior can achieve remarkable post-earthquake repairability, as evidenced by residual inter-story drifts below 0.5% with 99% probability subjected to the maximum considered earthquakes.
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