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.
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.
•New procedure to evaluate the behaviour factor for CLT structures.•Results of Experimental investigations on connections and wall elements.•Derivation and validation of properties of nonlinear ...springs.•Development of reference structures and consistent structural models for CLT.•Performing nonlinear static (pushover) analyses.•Application of displacement-based design (DBD) to CLT structures.•Confirmation of a behaviour factor for the CLT construction by DBD.
Different aspects of force-based and displacement-based design of multi-storey cross-laminated timber (CLT) structures are discussed in the context of the definition of the behaviour factor q. A review of approaches to determine the behaviour factor for force-based design will be given. A new approach to evaluate the behaviour factor based on non-linear static analyses together with a displacement-based design procedure will be discussed and demonstrated. CLT structures with two and four storeys and different types of structural models are considered for illustration and validation. Results of experimental investigations on anchoring connections will be presented. These test data are employed to derive properties of non-linear springs for structural modelling. The spring properties will be validated by comparison of analytical to experimental results on the wall level. An appropriate behaviour factor can be found based on the evaluation of 24 different structural configurations.
In this study, an assembled self-centering buckling-restrained brace (ASC-BRB) is developed for seismic resilience of structures. The self-centering system of the brace mainly consists of a group of ...disc springs and two sets of steel strands in series to enhance the deformability and achieve the post-hardening behavior for limiting the rapid displacement development of structures under extreme earthquakes. The theoretical restoring force model is first derived according to the working principle of ASC-BRB and successfully validated by experiments. An empirical ductility demand spectral model of ASC-BRB frames is developed according to the parametric analysis on the seismic responses of the corresponding nonlinear single-degree-of-freedom (SDOF) system. The spectral model considers the influences of all independent hysteretic parameters of ASC-BRB, and the physical parameters of the brace can be determined directly from the complete hysteretic parameters. Then a displacement-based seismic design procedure for designing ASC-BRB frames is proposed. The design results indicate that the designed frames generally need at most one iterative design to meet the target performance. Although the ASC-BRBs are designed with partial self-centering behavior, the frames can still exhibit approving post-earthquake recoverability with negligible residual displacements under strong earthquakes when the values of brace hysteretic parameters are chosen reasonably. When designing ASC-BRB frames, a strength ratio β of 0.25 and a strength ratio of steel strands η2 of 0.2 is recommended for improving the seismic performance and post-earthquake resilience of structures. Compared with the existing SC-BRBs with much higher initial stiffness, the proposed ASC-BRB can control the structural peak floor acceleration more effectively, which is beneficial for non-structural components.
•A novel assembled self-centering buckling restrained brace (ASC-BRB) is proposed.•The ductility demand spectral model for ASC-BRB frames is developed.•A displacement-based seismic design procedure for ASC-BRB frames is proposed.•The design approach is applicable for ASC-BRB frames with different hysteretic parameters.•The designed partial self-centering ASC-BRB frames exhibit satisfactory recoverability even after the maximum considered earthquakes.
Direct displacement-based seismic design has been recently proposed for the seismic design of non-structural building elements. This paper deals with the development of damping models, relating ...equivalent viscous damping ratio to drift amplitude, for suspended piping trapeze restraint installations for direct displacement-based seismic design. The damping models are developed using reversed cyclic test data available in the literature. First, damping models are proposed using Jacobsen's equal area approach. The damping models developed using Jacobsen's approach are then assessed and calibrated using nonlinear time history analyses of single degree-of-freedom archetypes representing suspended piping trapeze restraint installations in buildings.
Displacement-based seismic design often requires nonlinear time history simulation of building responses which is computationally intensive. This technical note presents an artificial neural network ...(ANN) designed to generate max inter-story drift for buildings with post-tensioned mass timber (MT) rocking walls systems. This particular lateral system was selected because it is an innovative system with limited physical design parameters, making it an ideal candidate for ANN. The proposed model achieved significantly higher computational efficiency than time history simulation, while maintaining similar level of accuracy. The proposed method could potentially be used for automated design of MT rocking wall lateral systems.
Direct displacement-based seismic design has been proposed for pallet-type steel storage racks. Damping models are developed in this study for pallet-type steel storage racks in the down-aisle and ...cross-aisle directions for use in direct displacement-based seismic design. The damping models are developed using results from reversed cyclic tests at a component level or at a system level. Jacobsen's approach is used to develop a first set of damping models. The damping models are then assessed using results from nonlinear time-history analyses. Finally, the damping models are calibrated using an iterative procedure based on results from nonlinear time-history analyses.
It is convenient to use the inelastic displacement ratio spectra and residual displacement ratio spectra to predict the maximum inelastic displacement and residual displacement of building structures ...based on linear elastic analysis directly. The prestressed concrete wall system with friction devices (PCW-FD system) can be simulated by single-degree-of-freedom (SDOF) model with self-centering behavior. To investigate the seismic performance of PCW-FD system, the SDOF models with fully and non-fully self-centering behavior are analyzed firstly, and it is concluded that the hysteresis parameters (strength reduction coefficient, post-yield stiffness coefficient, energy dissipation coefficient, and period) have significant influence on the seismic responses (such as constant relative strength inelastic displacement ratio, constant relative strength residual displacement ratio, maximum absolute acceleration, the hysteretic energy, and site classifications) during short period, and the trends of the seismic responses are similar at different site classifications. Then a large amount of the result data is summarized, and the constant relative strength inelastic displacement ratio spectra and the constant relative strength residual displacement ratio spectra with enough precision (the correlation coefficients are 0.957 and 0.947, respectively) are established by conducting regression analysis. Finally, the direct displacement–based seismic design method is improved and verified to be suitable for PCW-FD system.
Passive energy dissipation devices have been proved to be effective and low-cost means of structural control, and a variety of dampers have been developed over the past decades. Hysteretic dampers ...with hardening post-yielding stiffness have multiphased energy dissipation characteristics because of their hardening behavior, which can compensate for stiffness loss and postpone the collapse of damaged structures. In this article, a hysteretic model is proposed for hysteretic dampers with hardening post-yielding stiffnesses, and a formula is derived for equivalent yield strength expressed by the additional damping of the structure. A procedure is developed for displacement-based seismic design that transforms the relatively complex damping into an acceptable yield strength. A numerical example is only presented for demonstrating the design process and simply validating the proposed method. The results show that the proposed procedure is easy to implement and could produce adequate hysteretic dampers with hardening post-yielding stiffness hardening behavior. The maximum displacement responses of the existing structure retrofitted using the proposed procedure satisfy the expected performance objective well. Thus, this procedure could be an alternative to seismic retrofitting for structures with energy dissipation systems.
