Performance Of Nonstructural Components Research Articles

Educating non-specialized audiences about seismic design principles using videos and physical models

The prevalence of self-construction practices in Türkiye has resulted in a building stock whose earthquake resilience is highly uncertain. To mitigate the potentially devastating impact of anticipated large earthquakes, one viable approach is to increase earthquake awareness among builders themselves. However, these builders lack formal engineering training and are ordinary citizens. Therefore, the challenge lies in devising visual teaching methods, such as short videos, to explain complex seismic phenomena in a comprehensible manner. This paper introduces the use of educational media tailored for non-specialized audiences, encompassing regular citizens and students without engineering backgrounds. These videos are based on experiments conducted with physical models on a homemade shake table. They focus on key factors influencing the seismic response of multi-storey buildings and highlight common design and construction errors that lead to building damage. To assess the effectiveness of this approach, we conducted a workshop with junior architecture students, followed by post-workshop qualitative assessments through knowledge surveys and interviews. The findings indicate that while single-topic videos were effective learning tools for students without prior knowledge of seismic building design, students found models particularly useful for explaining specific concepts such as torsional behavior, the role of diaphragms, and the performance of non-structural components. However, despite positive feedback on the effectiveness of model testing, students generally did not perceive significant knowledge acquisition in model construction. Ultimately, the accessibility of freely available videos, coupled with their enhanced educational value, makes them effective tools for raising seismic awareness in communities vulnerable to future earthquakes.

Defining Design Parameters for Controlled Rocking Braced Frames to Control Seismic Losses

ABSTRACT Controlled rocking braced frames (CRBFs) are a self-centering lateral force-resisting system aimed at reducing structural damage potential. Previous research has shown that relatively low design forces for rocking and for structural elements in CRBFs would be acceptable based on collapse fragility analysis. However, past studies have also highlighted the potential for significant story drifts and for increased demands on acceleration-sensitive nonstructural components installed in buildings with CRBFs. Therefore, while CRBFs have demonstrated acceptable performance in terms of collapse across a wide range of design options, these design options must be evaluated considering the performance of nonstructural components if the intended low-damage potential of CRBFs is to be fully realized. To address this need, this paper investigates the influence of two key design parameters on seismic losses of buildings with CRBFs, namely the response modification factor (R) for the rocking joint design and the amplification factor (γ) used to incorporate higher-mode forces into the capacity design of frame members. Three different heights of CRBF buildings are designed using different design options, with values of R ranging from 5 to 12 and with higher-mode forces considered based on two seismic intensity levels: the design earthquake (DE) and the maximum considered earthquake (MCE). Then, following an assessment of structural responses, the paper’s primary emphasis is on earthquake-induced economic losses. While the computed total expected annual losses (EALs) using various design options are remarkably similar, the distribution of losses attributed to collapse or to nonstructural components varies. The CRBFs with lower resistance to rocking exhibit greater losses attributed to collapse and to drift-sensitive nonstructural components, but this is counterbalanced by a simultaneous reduction in losses related to acceleration-sensitive nonstructural components. Furthermore, in taller CRBF buildings, using amplified higher-mode forces based on the MCE level slightly decreases total EALs compared to those using the DE level, primarily due to a reduction in collapse losses.

Assessment of the effects of non-structural components on the seismic reliability of structures via a block diagram method

Under a specific ground motion excitation, even if structural components all satisfy a target performance level, the serviceability of the structure might get affected by the performance of non-structural components. Although the overall performance of a structure is affected by the performance of both structural and non-structural components, seismic reliability and fragility analyses usually only focus on the structural elements and their load-carrying capacity. The present study aims to assess the influence of the acceleration-sensitive non-structural components on the seismic reliability of the entire structure. The distinguishing feature of the proposed approach is the adoption of reliability block diagrams for the analysis of each structure, allowing for different combinations of damage for structural and non-structural components. Results are shown for 5-, 10- and 15-story buildings, to demonstrate the significant effects of non-structural components on their overall seismic reliability. Such effects prove to be more evident for the lower damage levels, and the higher seismic intensities. It is shown that non-structural components can lead to a reduction of the overall seismic reliability ranging from 22% to 100%, for situations related to the life safety and collapse prevention performance levels, under the effects of the design basis and maximum considered earthquakes, respectively.

Demands on nonstructural components in buildings with controlled rocking braced frames

AbstractControlled Rocking Braced Frames (CRBFs) have been developed as a high‐performance seismic force resisting system that can self‐center after an earthquake and avoid structural damage. A CRBF is designed to uplift and rock on its foundation, and this response is controlled using prestressing and energy dissipation devices that are engaged by uplift. Although CRBFs have been shown to have desirable structural performance, a comprehensive assessment of this system must also consider the performance of nonstructural components, which have a significant impact on the safety and economic viability of the system. The purpose of this paper is to evaluate the demands on nonstructural components in buildings with CRBFs in comparison to demands in a reference codified system, taken here as a buckling restrained braced frame (BRBF), as well as to identify which design parameters influence these demands. The responses of various types of nonstructural components, including anchored components, stocky unanchored components that slide, and slender unanchored components that rock, are determined using a cascading analysis approach, where absolute floor accelerations generated from nonlinear response history analyses of each system are used as input for computing the responses of nonstructural components. The results show that the downside of maintaining elastic behavior of the CRBF members is, in general, larger demands on nonstructural components compared to the BRBF system. These demands are not highly influenced by impact during rocking or by the supplemental energy dissipation provided, as the vibration of the CRBF in its higher modes is primarily responsible for the higher demands.

Performance of battery rack auxiliary power systems under FEMA 461 quasi-static seismic loading protocol

The performance of nonstructural components in nuclear power plants (NPPs), which is primarily based on experience and historical data, has been attracting increased interest from researchers following the Fukushima Daiichi nuclear disaster in 2011. This disaster demonstrated the importance of using batteries in NPPs as an auxiliary power system, where such systems can provide the necessary power to mitigate the risk of serious accidents. However, little research has been conducted on such nonstructural components (e.g., auxiliary battery power systems) to evaluate their performance following the post-Fukushima safety requirements, recommended by several nuclear regulators worldwide [e.g., Nuclear Regulatory Commission (NRC), and Nuclear Safety Commission (NSC)]. To address this research gap, the current study investigates the lateral performance of an auxiliary battery power system similar to those currently existing/operational in NPPs in Canada. The rack system was experimentally tested under displacement-controlled quasi-static cyclic fully-reversed loading that simulates lateral seismic demands, following the FEMA 461 guidelines “Interim testing protocol for determining the seismic performance characteristics of structural and nonstructural components”. Following a brief summary of the experimental program, the test results are presented in terms of the rack hysteretic response, damage sequence, stiffness degradation, ductility capacity, member strains, and local deformations. Subsequently, a simplified mechanistic model and a concentrated plasticity model in OpenSees have been developed and calibrated using the experimental results. The results show that without detailed modeling of the rack system connections (i.e., L-shaped connection and sliding nuts), incorrect performance prediction of such systems may result. The findings of the current study can be utilized, within the next generation of performance-based seismic design approaches, to enhance the robustness and improve the reliability of damage state predictions of auxiliary battery power systems in critical facilities.

Optimization of uncertain and dynamic high-rise structures for occupant comfort: An adaptive kriging approach

Performance requirements concerning serviceability often govern the design of high-rise structures. While various methods have been proposed for obtaining optimal systems that meet serviceability constraints set on the performance of non-structural components, e.g. the cladding system, methods are still lacking for optimizing under constraints aimed at ensuring occupant comfort. This is especially true for systems whose performance is assessed within modern performance-based design frameworks that consider a full range of uncertainties, including wind loads modeled as stochastic processes. This paper is focused on the development of a novel optimization framework for overcoming these limitations. The method is based on constructing an adaptive kriging metamodel of the probabilistic performance metric of interest in the low-dimensional modal space of the system. By then relating this space to the design variables, an approach is defined that can handle a wide class of occupant comfort metrics within high-dimensional spaces of design variables and uncertain parameters.