Performance-based Design Framework Research Articles

High strength steel frames with curved knee braces: Performance-based damage-control design framework

High strength steel frames with curved knee braces (HSSFs-CKBs) are typical seismic resilient structural systems. Previous experimental research showed that an HSSF-CKBs specimen could be readily repaired after an earthquake by replacing damaged curved knee braces (CKBs) which serve as energy dissipating devices, as long as high strength steel components stay essentially elastic to shake down post-earthquake residual deformations. To provide a practical tool for engineers in seismic resilience design, this paper developed a performance-based damage-control design framework for low-to-medium rise HSSFs-CKBs. A multi-storey HSSF-CKBs was first interlinked with an equivalent bilinear single-degree-of-freedom (SDOF) system. Then, the seismic input energy demand of the HSSF-CKBs was determined based on the seismic energy balance of the equivalent SDOF system, which was further distributed to different storeys to design structural components. To facilitate the design, a stepwise design procedure was proposed. A three-storey low-rise HSSF-CKBs and a six-storey medium-rise HSSF-CKBs were designed following the procedure. The seismic response of the designed structures was examined by pushover analyses and nonlinear time-history analyses using numerical models verified by shaking table test data. The analysis results showed that the designed structures exhibited the expected behaviour, and the maximum interstorey drifts were controlled below the design target, which verified the effectiveness of the proposed design framework.

Design-Oriented Energy Capacity Spectrum Method for Seismic Performance Control of Precast Concrete Structures with Semirigid Connections

To effectively control the seismic performance of precast concrete (PC) frames with semirigid connections under strong earthquakes, a damage-oriented energy capacity spectrum method is proposed under the performance-based seismic design (PBSD) framework. The energy dissipation capacity (EDC) spectrum corresponding to an equivalent single-degree-of-freedom (SDOF) system of a PC frame is derived based on the Coffin–Manson low-cycle fatigue model of connections and expressed as a function of the displacement response. The related parameters are experimentally and numerically calibrated. To ensure consistency with the EDC spectrum, the hysteretic energy demand (HED) spectrum is developed based on a pseudo-acceleration spectrum, a ductility spectrum, and two energy spectra. The relation between the connection damage and structural damage is employed to establish the damage-oriented EDC spectra. The performance point is iteratively determined, from the intersection points of the EDC and HED spectra at different damage levels, until the specified objective overall damage performance is satisfied. The implementation of the damage-oriented design procedure on a 12-story PC frame with semirigid connections indicates that the EDC spectra corresponding to the three modes agree well with the predictions, and the overall damage indexes obtained from the time history analyses (THAs) are consistent with those obtained from the solution of the performance points. The damage performance objective for PC frames with semirigid connections can be attained by adjusting the design yield moments of the connections by exploiting their adaptability.

Probabilistic demand models and performance-based fragility estimates for concrete protective structures subjected to missile impact

The manifold missile attacks upon structures and deficiency of codal provisions motivated the current study to develop probabilistic demand models for protective structures subjected to hard missile impact. These energy-based models are estimated using a defined performance-based design framework (PBD) with three performance levels associated with four damage states, i.e. from minor damage to total collapse. The evaluation of unknown model parameters is constructed using the Bayesian approach. The current and upcoming range of structural variables is chosen for numerical experimental design. LS-DYNA, a finite element (FE) numerical method, is used to generate necessary probabilistic data of Reinforced Concrete (RC) & Prestressed Concrete (PC) panels subject to a hard missile. Novel formulations for local damages of a target, such as perforation limit of RC panel & Ballistic limit of the missile for RC & PC panels, are estimated. The developed demand models are used to assess the fragility estimation of either panel under chosen performance levels for a containment structure located in Tarapur, Palghar, India. An accurate fragility plot and comparative study shows the consistency of probabilistic models with test results. These models consider aleatory and epistemic uncertainties in modeling, material & geometrical properties, strain rate & inertia effect, and complex interaction involved in an impact scenario.

Performance-based probabilistic capacity models for reinforced concrete and prestressed concrete protective structures subjected to missile impact

A performance-based design (PBD) framework for nuclear containment structure (NCS) subject to missile impact is developed. These are, in turn, used to estimate probabilistic energy-based capacity models centred on three performance levels associated with four damage states of NCS. The present study considers multi-level PBD as opposed to single-level conventional collapse based design. Bayesian inference is used to evaluate the unknown model parameters based on available numerical data. The data of reinforced concrete (RC) and prestressed concrete (PC) panels subjected to hard missile impact is obtained from finite element (FE) numerical modelling (LS-DYNA). Formulations for local damages such as penetration depth, perforation limit and residual velocity of the missile are also developed. The established models account for the multi-modal response of the structure, the transition of failure modes and their interaction, inherent aleatoric and epistemic uncertainties associated with the modelling, configuration and material properties. A comparative study is performed with these predicted models and experimentation achieves the desired prediction level. These probabilistic models can be used for designing the NCS when subject to ballistic missiles. The work can also be extended to scenarios like ship collisions, vehicles falling on slabs due to tornadoes by following the developed framework. Not alone NCS the obtained results accommodate other protective structures like bunkers, storage tanks, residential slabs, and many similar configurations considered in the study.

Pareto-optimal performance-based robust design of braced excavations in soft clay with response surface methodology

This paper presents a methodology for robust design optimization of braced excavations in soft clay with response surface methodology based on the pareto-optimal trade-off between system performance and cost. As prediction of maximum ground settlement induced by excavation is generally accompanied by an implicit numerical model, the response surface methodology is employed to build the performance function with respect to both design parameters and uncertain geotechnical parameters. Then a pareto-optimal performance-based robust design framework of braced excavations in soft clay is formulated to find the optimal design that meets the design requirements while optimizing the system performance and construction cost. With the aid of a multi-objective optimization approach, trade-off relationship between performance robustness and cost efficiency are developed to help identify the most robust design based on the targeted performance levels. A design example of braced excavation in Taipei soft clay is used to illustrate the significance of the proposed methodology.

Inelastic Performance of High-Rise Buildings to Simultaneous Actions of Alongwind and Crosswind Loads

AbstractCurrent tall building design to ultimate wind loads is based on a linear elastic design framework. The adoption of a performance-based wind design framework for tall buildings explicitly re...

Integration of peak seismic floor velocities and accelerations into the performance-based design of steel structures

This paper elaborates towards the homogenization of the seismic behavior between the structural and non-structural components of steel structures in the framework of performance-based seismic design. In particular, for the seismic performance level that the steel structure is set to satisfy, simple expressions that relate peak seismic floor velocity and acceleration with their corresponding peak ground counterparts are provided. These expressions are functions of the number of stories and are derived by non-linear regression analyses of the peak seismic floor velocity and acceleration data derived by non-linear time-history analyses of various steel structures subjected either to far-fault, or to near-fault seismic motions. Numerical examples are presented in order to demonstrate the efficiency and range of applicability of the proposed expressions. It is concluded that by means of the proposed expressions, the seismic performance of a class of acceleration- or velocity-susceptible non-structural components in steel structures is expected to be in line with that of the structural components.

Structural response of reinforced concrete volumetric building in low seismicity regions

Recent advancement in offsite volumetric construction shows that volumetric buildings (VB) are getting popular among the prefabrication industry. Although volumetric construction has been used to build numerous tall buildings in Singapore and Australia, its structural behavior is not thoroughly researched and published in the literature. Hence, this paper examines the structural response of centric reinforced concrete VBs of 10-story and 25-story through a performance-based design framework using finite element modelling. These VBs are first designed elastically under wind actions, then subject to incremental secant stiffness response spectrum analysis for seismic actions. The Eurocode 8 Malaysian National Annex is used to simulate various ground types according to site natural period. The base shear contribution of RC module to the lateral force-resisting system of VB was found to be significant, and a high ratio of seismic-to-wind demand was expected for VB situated in the low-seismicity region such as Malaysia.

Performance-based seismic design framework for inertia-sensitive nonstructural components in base-isolated buildings

Damage to building structural systems during earthquakes has led to significant downtime and economic losses, and, in some cases, to demolition of the buildings themselves. Failure of nonstructural components have also been a major contributor to the economic losses and are known to have threatened the lives of building inhabitants. As a result, investigations in many regions in the world that have experienced strong shaking causing damage to buildings have opted to incorporate base isolation as an earthquake protection measure. As base isolation of buildings becomes more widespread, especially for hospitals, emergency centers, and other buildings with critical functions and/or valuable contents, it is necessary to ensure nonstructural components within these buildings are appropriately designed and detailed. Currently, the design of the fastenings of critical nonstructural components in base-isolated buildings is performed using prescriptive code requirements developed for conventional fixed-based buildings that have entirely different dynamics. This paper describes a performance-based seismic design framework for developing design equations for nonstructural components within base-isolated buildings. The framework utilizes displacement damage limit-states of the components to determine the design lateral force. An example of how to apply the framework is illustrated via a case study that combines experimental structural responses recorded during the shake table testing of a base-isolated building with simulated nonlinear nonstructural component responses.

Seismic collapse safety analysis of performance-based optimally designed reinforced concrete frames considering life-cycle cost

The present paper aims to assess the seismic collapse capacity of reinforced concrete (RC) frames optimized in the context of performance-based design. The proposed methodology in this work consists of two main phases namely, performance-based design optimization and seismic collapse safety assessment. In the first phase, an efficient metaheuristic algorithm is employed to carry out single-objective optimization of RC frames in the framework of performance-based design with two different objective functions including initial construction cost and total cost. In the second phase, the seismic collapse capacity of optimally designed RC frames is evaluated by conducting seismic fragility analysis. Three illustrative examples of 3-, 6-, and 12-story RC frames are presented to demonstrate the capability of the proposed methodology for designing of cost-efficient structures with considerable seismic collapse safety.

Inelastic Displacement Ratios for SDOF Structures Subjected to Earthquake-tsunami Loadings

ABSTRACT This study investigates the inelastic displacement of structures subjected to earthquake-tsunami loadings. The relative intensity is defined as the ratio of the tsunami force per unit mass to the S a of the corresponding ground motion. The effects of the hysteretic model, soil condition, post-yield stiffness, damping, and relative intensity on the inelastic displacement ratios are investigated. The results show that, compared to earthquakes alone, earthquake-tsunami loadings can enlarge the inelastic displacement ratio demands, especially for higher relative intensities. A predictive model is developed by considering several parameters, which may be used in the framework of performance-based seismic design.

A versatile numerical model for the nonlinear analysis of squat-to-tall reinforced-concrete shear walls

Reinforced concrete (RC) walls are extensively used to resist lateral forces in tall buildings as well as in the majority of medium to low-rise structures designed for protective purposes. In the framework of seismic performance-based design, where an adequate modeling of the lateral load versus lateral displacement relationship and a full understanding of the damage evolution are required, numerical models represent an effective tool to conduct nonlinear response analyses of such systems. For practical applications and for performing extensive nonlinear analyses, it would be desirable to have a robust yet simple numerical model that is capable of capturing the global and local characteristics of the response for different levels of damage. To this end, this paper presents a finite element-based model implemented in OpenSees [1] capable of simulating the in-plane nonlinear static and dynamic response of RC walls across a broad range of aspect ratios. The proposed model includes (i) the element technology, in which the state-of-the-art isoparametric elements are coupled with layered sections, and (ii) a novel plane-stress plastic-damage concrete material. A simple simulation-based method for determining the concrete material parameters is proposed. Model validation is conducted through a comprehensive comparison against experimental tests collected from the literature. Results show that the proposed numerical tool can be reliably used to simulate the nonlinear global and local response of RC walls spanning a broad range of aspect ratios (from 0.4 to 2.3). Moreover, model hysteresis damping is analytically analyzed to provide modelers with insight into the equivalent damping to employ when nonlinear and equivalent linear dynamic analyses are performed with the proposed model. Finally, an extensive parametric study comprising a total of 12,288 nonlinear simulations is developed to investigate the sensitivity of the numerically predicted response to changes in the concrete model parameters and gain insight into the factors that most affect the walls peak shear and dissipated energy.

Performance-Based Design Framework for Concrete Barriers Subjected to Truck Collision

Abstract A validated computational model is used to investigate the response of concrete barriers subjected to impact by single-unit trucks and tractor-semitrailers with different weights and appro...

Performance-based design framework for wind turbine towers to improve lifetime profitability

Wind turbine tower (WTT) is a vital part of wind energy development, which gains huge momentum globally over the past decades. In this study, an ingenious solution is provided with the proposed performance-based design framework for the WTTs. To represent the performance of the wind projects, an intuitive variable, i.e., the expected lifetime profit, is considered as the performance index. The fragility functions were used to probabilistically incorporate the uncertainties from the characteristics of natural hazards, the structural capacity estimations, the variations in geometric irregularities of towers, etc. The lifetime profit were roughly estimated based on the structural performance associated with the existing economic data collected from the current WTT projects. Furthermore, with a hypothetical case study, this paper presents a solution to improve the structural performance using the proposed methodology. The influences of the initial costs as well as the operation and maintenance costs on the profit were also investigated. The final profit and the profit-operating time curves were provided, which are valuable references to the designers, the owners and the insurers of the wind farm projects.

Límites de esbeltez basados en prestaciones para vigas de hormigón armado para el control de deformaciones y el control de tensiones en la armadura

Los procedimientos actuales de dimensionamiento a flexión de elementos de hormigón armado, basados ​​en la comprobación de estado límite último (ELU), proporcionan suficiente resistencia para soportar las cargas de diseño con un canto reducido. Sin embargo, las dimensiones estrictas de la sección transversal y la cantidad de armadura calculada para satisfacer el ELU pueden ser insuficientes para evitar deformaciones excesivas que pueden producir daños en los elementos no estructurales, o para garantizar el control de la fisuración y satisfacer así, los requisitos de durabilidad, funcionalidad o estética.Debido a la complejidad asociada a un cálculo riguroso de las deformaciones y el ancho de fisura en elementos de hormigón armado a lo largo de su vida útil, una forma efectiva de garantizar la satisfacción del estado límite de servicio es mediante la limitación de la relación de esbeltez l/d del elemento. En el presente estudio, el concepto de esbeltez límite, utilizado anteriormente para el control de la deformación, se generaliza para incorporar las limitaciones de la abertura de fisura, en el marco del diseño estructural basado en prestaciones. Por ello, se derivan las ecuaciones para la esbeltez límite que incorporan los parámetros principales que influyen en el comportamiento de servicio de los elementos de hormigón armado, que son válidos para secciones transversales rectangulares en forma de I o T y para elementos simplemente apoyados o continuos. La fisuración y los efectos a largo plazo se explican a través de coeficientes simplificados derivados de la mecánica estructural y las observaciones experimentales.Las esbelteces límite propuestas, tanto para una carga aplicada constante como para una deformación en la armadura constante, se comparan con las obtenidos utilizando el procedimiento EC2 para el cálculo de deformaciones, basado en la integración de curvaturas. Se han obtenido buenos resultados en términos de errores y dispersión, lo que demuestra que las esbelteces límite propuestas son una herramienta útil para el diseño basado en prestaciones de estructuras de hormigón armado. El carácter mecánico de la formulación facilita su modificación para situaciones diferentes a las utilizadas en su deducción, por ejemplo, diferentes tipos de carga, vigas parcialmente pretensadas o elementos de hormigón armado con FRP, entre otros.

Smart performance-based design for building fire safety: Prediction of smoke motion via AI

The performance-based design (PBD) has been widely adopted for building fire safety over the last three decades, but it requires a laborious and costly process of design and approval. This work presents a smart framework for fire-engineering PBD to predict the smoke motion and the Available Safe Egress Time (ASET) in the atrium by Artificial Intelligence (AI). A CFD database of visibility profile in atrium fires is established, including various fire scenarios, atrium volumes, and ventilation conditions. After the database is trained with the transposed convolutional neural network (TCNN), the AI model can accurately predict the smoke visibility profile and ASET in the atrium fire. Compared to conventional CFD-based PBD by professional fire engineers, AI method provides more consistent and reliable results within a much shorter time. This research verified the feasibility of using AI in fire-engineering PBD, which may reduce the time and cost in creating a fire-safety built environment.

Performance-based wind design framework proposal for tall buildings

Performance-based seismic design (PBSD) is currently used for retrofitting of older buildings and the design of new buildings. Whereas, application of performance-based design for wind load is still under development. The tendency has been in the codes to increase wind hazard based on recent recorded events. Since tall buildings are highly susceptible to wind load, necessity for developing a framework for performance-based wind design (PBWD) has intensified. Only a few guidelines such as ASCE (2019) provide information on using PBWD as an alternative for code prescriptive wind design. Though wind hazards, performance objectives, analysis techniques, and acceptance criteria are explained, no recommendations are provided for several aspects like how to select a proper level of wind hazard for each target performance criterion. This paper is an attempt to explain current design philosophy for wind and seismic loads and inherent connection between the components of PBSD for development of a framework for PBWD of tall buildings. Recognizing this connection, a framework for PBWD based on limits set for serviceability and strength is also proposed. Also, the potential for carrying out PBWD in line with ASCE 7-16 is investigated and proposed in this paper.

Influence of buried depth on seismic capacity of underground subway stations through performance-based evaluation

Buried depth is an important physical factor that affects the seismic performance of underground structures yet remains scarcely considered in existing seismic design. This paper aims to determine the influence of buried depth variation on the seismic capacity of underground subway stations in the framework of performance-based seismic design with particular focus on the influence on the inter-storey drift ratio limit. A brief introduction is presented to determine the performance level of subway station structures based on the pushover method. The influence of buried depth on the seismic performance index (inter-storey drift ratio) of subway station structures is investigated, as well as its influence on the shear distribution and failure mode of the key structural component, that is the middle column. It is found that the inter-storey drift ratio limit generally decreases with increasing buried depth and the station ductility worsens. The failure mode of the middle column changes from large eccentric compression to small eccentric compression with increasing buried depth owing to increased axial compression. The results are applied to estimate an optimum buried depth that improves the overall safety of subway station structures.

Deformation-dependent peak floor acceleration for the performance-based design of nonstructural elements attached to R/C structures

This study introduces a simple and efficient method to determine the peak floor acceleration (PFA) at different performance levels for three types of plane reinforced concrete (RC) structures: moment-resisting frames (MRFs), infilled–moment-resisting frames (I-MRFs), and wall-frame dual systems (WFDSs). By associating the structural maximum PFA response with the deformation response, the acceleration-sensitive nonstructural components, and the building contents, can be designed to adhere to the performance-based seismic design of the supporting structure. Thus, the proposed method can accompany displacement-based seismic design methods to design acceleration-sensitive nonstructural elements to comply with the deformation target of the supporting structure. The PFA response shape is represented by line segments defined by key points corresponding to certain floor levels. These key points are defined by explicit empirical expressions developed herein. The maximum PFA response is correlated with the maximum interstory drift ratio (IDR) and other vital characteristics of the supporting structure such as the fundamental period. The proposed expressions are established based on extensive nonlinear dynamic analyses of 19 MRFs, 19 WFDSs, and 19 I-MRFs under 100 far-fault ground motions scaled to capture different deformation targets. Realistic examples demonstrate the efficiency of the proposed method to assess the PFA response at a given IDR, making the method suitable in the framework of performance-based design.

A multi-modal-analysis-based simplified seismic design method for high-rise frame-steel plate shear wall dual structures

In this paper, a simplified seismic design method of high-rise frame-steel plate shear wall (SPSW) system was proposed based on the multi-modal-analysis under the framework of performance-based seismic design. The seismic response of high-rise SPSW system was simplified to first and multiple-modal equivalent single degree-of-freedom (SDOF) oscillators. The dual frame-SPSW structure was decomposed into a frame system and SPSW system by controlling the relative contribution of SPSW system, and they were correspondingly simplified to a series of F-SDOF oscillators and S-SDOF oscillators. The analytical models of F-SDOF and S-SDOF oscillators were developed using the modal pushover analysis. By assuming the system responding linearly elastic for higher modes, the equivalent SDOF oscillator (D-SDOF) for the frame-SPSW system was developed by combining the F-SDOF and S-SDOF oscillators in parallel for each mode of vibration. The design procedure was developed based on the comparison of displacement thresholds against the displacement demands derived using the SRSS combination. A 15-story frame-SPSW system was adopted to verify the feasibility and demonstrate the design process of the simplified method. The result also shows the seismic demands derived by the equivalent dual SDOF oscillators have good consistency with that by frame-SPSW structure.