Performance-based earthquake engineering requires the harmonization of performances between structural and nonstructural elements. This paper discusses the performance-based seismic design of ...nonstructural elements through a direct displacement-based methodology applicable to nonstructural elements attached to a single location in the supporting structure and for which damage is the result of excessive displacements. The fundamentals of direct displacement-based seismic design are presented along with a description of the modifications required for its application to nonstructural elements. As an example, the direct displacement-based seismic design of a suspended piping restraint installation is presented. The design approach is appraised by nonlinear dynamic time-history analyses.
•The applicability of bond design in current design codes to beam-column joints using slag-based geopolymer concrete (GC) was evaluated.•The limit of hc/db ≥ 20 in GB50010-2010 and ACI 318-19 are not ...safe for reinforced GC interior beam-column joints.•The bond performance of 90˚ hooked bars was superior to that of headed bars in reinforced GC exterior beam-column joints.•Current design codes are applicable to the development length of 90˚ hooked bars in reinforced GC exterior beam-column joints.
An available study on the bond and anchorage performance of beam flexural bars in beam-column joints using slag-based geopolymer concrete (GC) is limited. The applicability of current design codes to beam flexural bars design in GC beam-column joints is unknown. In this study, to investigate the bond and anchorage performance of beam rebars at the GC beam-column joints and their effect on seismic performance, cyclic loading tests were performed on 2 reinforced GC interior beam-column joints and 6 reinforced GC exterior beam-column joints. The test results showed that the increase in column depth-to-beam rebar diameter ratio (hc/db) from 21 to 25 improved the bond performance of the beam flexural bars in the reinforced GC interior beam-column joints, which significantly improved the energy dissipation capacity. The limits of hc/db larger than 20 in GB50010-2010 (except seismic grade I that requires hc/db ≥ 25) and ACI 318-19 were not safe for reinforced GC interior beam-column joints. The limits of hc/db in Eurocode 8 and NZS3101 for low-strength concrete (fc′ ≤ 30 MPa) were applicable. In reinforced GC exterior beam-column joints, the bond and anchorage performance of 90˚ hooked bars was superior to that of the corresponding headed bars. Regardless of the anchorage details, the bond and anchorage performance of the reinforced GC exterior beam-column joints increased with the increase of the development length of beam flexural bars. In reinforced GC exterior beam-column joint design, the bar development length requirement of GB50010-2010 was applicable to both 90˚ hooked bars and headed bars. Eurocode 8, NZS3101, and ACI 318-19 were applicable to the development length of 90˚ hooked bars.
In the field of earthquake engineering, the advent of the performance-based design philosophy, together with the highly uncertain nature of earthquake ground excitations to structures, has brought ...probabilistic performance-based design to the forefront of seismic design. In order to
design structures that explicitly satisfy probabilistic performance criteria, a probabilistic performance-based optimum seismic design (PPBOSD) framework is proposed in this paper by extending the state-of-the-art performance-based earthquake engineering (PBEE) methodology. PBEE is traditionally
used for risk evaluation of existing or newly designed structural systems, thus referred to herein as forward PBEE analysis. In contrast, its use for design purposes is limited because design is essentially a more challenging inverse problem. To address this challenge, a decision-making layer
is wrapped around the forward PBEE analysis procedure for computer-aided optimum structural design/retrofit accounting for various sources of uncertainty. In this paper, the framework is illustrated and validated using a proof-of-concept problem, namely tuning a simplified nonlinear inelastic
single-degreeof-freedom (SDOF) model of a bridge to achieve a target probabilistic loss hazard curve. For this purpose, first the forward PBEE analysis is presented in conjunction with the multilayer Monte Carlo simulation method to estimate the total loss hazard curve efficiently, followed
by a sensitivity study to investigate the effects of system (design) parameters on the probabilistic seismic performance of the bridge. The proposed PPBOSD framework is validated by successfully tuning the system parameters of the structure rated for a target probabilistic seismic loss hazard
curve. The PPBOSD framework provides a tool that is essential to develop, calibrate and validate simplified probabilistic performance-based design procedures.
Dual structural systems with structural fuse such as linked column frame system (LCF) have two main performances, including the resistance to lateral seismic loads and the proper function of ...structural fuse to control deformation of the other members to remain in elastic phase. The achievement of these two functions is necessary for appropriate seismic design of these systems. Undoubtedly, despite the practical complexity, displacement-based seismic design methods are generally the best method for this purpose. In contrast, conventional force-based methods are relatively simple, but it cannot easily guarantee the desired performance. In this paper, a simplified force-based seismic design method is presented for linked column frame system based on parametric studies on different structures, which are designed with displacement-based method. In addition to simplicity, the proposed method has an appropriate accuracy in terms of achieving the performance objectives. For the parametric study, 18 prototype structures with various relative lateral stiffness of moment frame and linked column system are designed with the displacement-based method. Based on the results of the structures designed with desirable performance, the criteria are proposed for the force-based design method. Based on evaluating results, the structures designed by the proposed simplified force-based method properly reached the performance objectives.
•A force-based seismic design method for linked column frame system.•Displacement-based seismic design method is used for generating this method.•The proposed design method is very simple and fast with adequate accuracy.•An equation is defined for determination of interactional effect between moment frame and linked column systems.
A hybrid force/displacement (HFD) performance-based seismic design method is proposed for two types of plane reinforced concrete structures, i.e., infilled moment-resisting frames (I-MRFs) and ...wall-frame dual systems (WFDS). The HFD seismic design method is a force-based method which controls with high accuracy both structural and non-structural deformation limits. The behavior factor is related here to the inter-storey drift ratio and the member plastic rotation by taking into account both geometrical and dynamic structural characteristics. The HFD is herein developed through an extensive parametrical study involving non-linear time-history analyses of 19 I-MRFs, and 19 WFDS under 100 far-fault ground motions.
Implementing energy dissipation braces can be an effective option for mitigating the seismic damage of double- or multi-column bridge bents. This study compares the relative effectiveness of ...different braces in seismically retrofitting a reinforced concrete (RC) double-column bent. The considered braces include buckling-restrained braces (BRBs), viscous damper braces (VDBs) and piston-based self-centering braces (PBSCs). First, a direct displacement-based design method (DBD) is utilized to design the braces for satisfying the same performance criterion under design earthquakes. Based on that, fragility analysis is conducted to evaluate the seismic vulnerability of the retrofitted bents subjected to near-fault and far-field ground motions. The self-centering performance of the retrofitted bents is also compared by using the post-earthquake residual displacement as a performance indicator. Results indicate that the PBSCs are more effective than BRBs and VDs in reducing the vulnerability of the bent at different damage states under either near-fault or far-field ground motions. In addition, the PBSCs are superior to the other braces in terms of self-centering performance by recovering more bent drift from an earthquake.
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.
Inelastic displacement ratios (IDRs) of nonlinear soil–structure interaction (SSI) systems located at sites with cohesive soils are investigated in this study. To capture the effects of inelastic ...cyclic behavior of the supporting soil, the Beam on Nonlinear Winkler Foundation (BNWF) model is used. The superstructure is modeled using an inelastic single‐degree‐of‐freedom (SDOF) system model. Nonlinear SSI systems representing various combinations of unconfined compressive strengths and shear wave velocities are considered in the analysis. A set of strong ground motions recorded at sites with soft to stiff soils is used for considering the record‐to‐record variability of IDRs. It is observed that IDRs for nonlinear SSI systems are sensitive to the strength and the stiffness properties of both the soil and the structure. For the case of SSI systems on the top of cohesive soils, the compressive strength of the soil has a significant impact on the IDRs, which cannot be captured by considering only the shear wave velocity of the soil. Based on the results of nonlinear time‐history analysis, a new equation is proposed for estimating the mean and the dispersion of IDRs of SSI systems depending on the characteristic properties of the supporting soil, dimensions of the foundation, and properties of the superstructure. A probabilistic framework is presented for the performance‐based seismic design of SSI systems located at sites with cohesive soils.
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.
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