Performance-based Plastic Design Research Articles

Improved performance-based plastic design method for post-tensioned connection systems

Performance-based plastic design (PBPD) was initially proposed as a method for retrofitting existing structures. The PBPD method gradually became a general approach for designing new structures. This method is a direct method to obtain design base shear and leads to design structures being more economical compared to traditional methods. PT connections were developed after the Northridge earthquake. The self-centering could restore the connection to its original position without damage to the beams and columns. High-strength post-tensioned cables are used to restore the structure to its initial position in PT connections. Also, energy dissipaters (for example, top and bottom angles) are used to increase ductility. In this study, a proposed relationship between the ductility (µ), period (T), and response reduction factor (R) is presented for structures with pinching or flag-shaped behavior, and the effect of the parameters on R has been investigated. Also, a new design approach for structures with PT-steel connections with top-and-bottom angles is presented. The results show that R primarily depends on the post-yield stiffness ratio (α), the yield stress ratio (or energy dissipation) (β), ductility (µ), soil type, etc. Nonlinear time-history analysis indicates that designed models based on the proposed approach satisfy drift limits. The results show that the proposed relationship can be quite suitable for designing PT connections using the PBPD approach.

Development of Performance Based Plastic Design of EBF Steel Structures Subjected to Forward Directivity Effect

Performance-based plastic design (PBPD) is a method which considers the inelastic behavior of a structure for the seismic design that follows a pattern in which a pre-selected yield mechanism is defined for each type of structural system. Despite the general adequacy of this method compared to the code-based method, the need to further improve this method against Forward-Directivity, the well-known characteristic of near-fault ground motions, is of high importance. On the other hand, Eccentrically Braced Frame (EBF) is considered to be an efficient conventional steel-framed system that combines the advantages of moment-resisting frame and concentrically braced frame. In this study, attempts have been made to improve the conventional PBPD method in order to consider the effect of forward-directivity. To this end, the energy modification factor (γ) was modified by recalculating ductility demand µ and ductility reduction factor Rµ of three 6-, 12-, and 18-story EBF structures. Using incremental dynamic analysis, these structures were subjected to 12 well-known near-fault ground motions, and accordingly, the modified energy factor (γ′) was obtained for each set. Then, an equation was proposed to calculate the γ′ based on the fundamental period of the structure. As expected, the code-based designed structures exceeded the allowable drift limits. Although the structures which were designed based on conventional PBPD followed the pre-selected yield mechanism and performed better, they exceeded the drift limits as well. Consequently, the structures which were re-designed using modified energy factor γ′ could well satisfy the acceptance criteria as well as achieving the desirable yield mechanism.

Probabilistic seismic performance evaluation of composite frames with concrete-filled steel tube columns and buckling-restrained braces

The concrete-filled steel tube (CFT) composite frames using blind bolts and buckling-restrained braces (BRBs) have been studied with the development of building industrialization and energy dissipation technology. However, there has been no research so far on the probabilistic seismic fragility analysis for the blind-bolted end-plate CFT composite frames with BRBs (BRB-BECFT). Therefore, a total of 6-, 9-, 12- and 20-story BRB-BECFT prototype structures were designed based on the performance-based plastic design method. The results obtained from nonlinear static and dynamic analyses indicated that the four structures achieved predefined performance objectives in terms of story drift, joint rotation, and BRB ductility demand. Subsequently, fragility curves including non-collapse and collapse states were established to evaluate the behavior of the structure for a given intensity measure using the incremental dynamic analysis approach. Meanwhile, the geometric mean of spectral acceleration over a period range (Sa,avg) was selected as the intensity measure to assess the structural collapse capacity. Results showed that the adoption of Sa,avg can result in 32–42% lower data dispersion for the determination of collapse point, and simplification of the process of calculation of the collapse margin ratio of a structure. Furthermore, based on the combination of Sa,avg, residual story drift and BRB core plate strain, a framework of probabilistic seismic damage analysis of structures for combined damage evaluation at three levels of the system, subsystem, and component was summarized and conducted by the 6- and 12-story case study. This is practically useful to assess structural damage state after an earthquake because it could present more information on the probability distribution of various damage scenarios.

New performance-based plastic design and evaluation of blind bolted end-plate CFT composite frames with BRBs

The blind bolted end-plate connection to concrete-filled steel tube column (BECFT) composite frame with buckling-restrained braces (BRBs, BRB-BECFT) is a novel dual structure system that combines advantages of fast assembly ability for BECFT connections, great energy dissipation capacity for BRBs coupled with BECFT connections and superior gravity load-carrying capacity for concrete-filled steel tube (CFT) columns. Given authors’ prior experimental and theoretical studies on the BRB-BECFT structure system, and as no design method is as far introduced for this system with adequate accuracy, a new plastic design procedure based on the modified energy balance and global yield mechanism in the framework of performance-based plastic design method was proposed. The post-yielding stiffness and overall yield inter-story drift of the BRB-BECFT structure system was considered to improve the accuracy of the design base shear. Meanwhile, the BRB-BECFT structure system was decomposed into the BRB system and BECFT frame system to simplify the design process. Moreover, some formulae to avoid structural adverse yield mechanism were derived. The semi-rigid characteristic of BECFT connections was introduced into the structural global yield mechanism by work-energy principle to ensure the deformation consistency between inter-story drift and BECFT connection rotation. Finally, four prototype structures with 6, 9, 12 and, 20 stories were designed as examples to illustrate the effectiveness and robustness of the proposed design method. The results of nonlinear time-history analyses showed that the designed structures successfully achieved the pre-selected performance objectives in terms of the inter-story drift, residual drift, BECFT connection rotation, and BRB ductility demands.

Performance-based-plastic design method of reinforced concrete structure for operational performance level

Under major load earthquakes, reinforced concrete structures designed according to the current codes will experience an inelastic deformation which is difficult to predict and control. Performance-based plastic design (PBPD) methodology is applied forward to design reinforced concrete structures in this study. In this method, as performance criteria, the target drift and yield mechanisms are preselected. Based on the work-energy balance principle, the design base shear is given as earthquake level and calculated as work required to push the structure as monotonically load to the target drift. The load equals the energy needed by an equivalent single degree of freedom in the same state. The plastic design is utilized to design the desired yield mechanism. The method was adopted on a 10-story reinforced concrete structure with an earthquake load in lateral forces based on SNI 1726:2019 and the Performance-Based Plastic Design (PBPD) method. Pushover analysis was carried out where the structure was pushed to obtain lateral load resistance followed by yielding gradually until plastic deformation occurred collapse From the pushover analysis, the ductility value for SNI 1726:2019 is less ductile than analytical using the Performance-Based Plastic Design (PBPD) method

Seismic control of concrete buildings with nonlinear behavior, considering soil structure interaction using AMD and TMD

The seismic analysis of structures without applying the effects of soil can undermine functional objectives of structure so that it can affect all the desired purposes at the design and control stages of the structure. In this research, employing OpenSees and MATLAB software simultaneously and developing a definite three-dimensional finite element model of a highrise concrete structure, designed using performance-based plastic design approach, the performance of Tuned Mass Damper (TMD) and Active Mass Damper (AMD) is both examined and compared. Moreover some less noted aspects such as nonlinear interaction of soil and structure, uplift, nonlinear behavior of structure and structural torsion have received more attention. For this purpose, the analysis of time history on the structural model has been performed under 22 far-field accelerogram records. Examining a full range of all structural seismic responses, including lateral displacement, acceleration, inter-story drift, lost plastic energy, number of plastic hinges, story shear force and uplift. The results indicate that TMD performs better than AMD except for lateral displacement and inter-story drift to control other structural responses. Because on the one hand, nonlinear structural parameters and soil-structure interaction have been added and on the other hand, the restriction on the control force applied that leads up to saturation phenomenon in the active control system affect the performance of AMD. Moreover, the control force applied by structural control system has created undesirable acceleration and shear force in the structure.

Strength, Deformation and Fragility assessment of Reinforced Concrete Moment Resisting frame designed by Force Based Design and the Performance Based Plastic Design method for Seismic loads

A 20 storied Reinforced Concrete (RC) Moment Resisting Frame (MRF) has been analysed and designed by Force Based Design (FBD) method and the Performance Based Plastic Design (PBPD) method. The PBPD frames were designed for all the three performance levels namely Immediate Occupancy, Life safety and Collapse Prevention of the basic safety objective. The guidelines of the Indian Standard codes along with established principles of design have been incorporated in the study. Nonlinear static pushover analysis was the tool used to evaluate the seismic performance of the frames in terms of strength and deformation. The fragility assessment has been carried out in terms of Spectral displacement obtained from the pushover analysis results for different specified damage states. Results indicate that PBPD method excels the FBD method, both in terms of seismic performance and fragility.

Displacement Analysis of RC Frames and its Seismic Performance Appraisal

In India when structure engineer’s analysis and design a structure like buildings, they are checking it for displacement because of safety and control of damages; so in this paper a set of frames with different height of reinforced moment resisting frames were analyzed by two popular methods of performance-based plastic design method and direct displacement-based design method. For calculation of base shear, the IS code has been used in both methods and ETABS software used for seismic performance evaluation by nonlinear static pushover analysis. The results of analysis with different methods compared by suitable parameters and graphs, such as: (a) story lateral force, (b) beam seismic moment, (c) displacement profile and (d) capacity curve. Results show acceptable performance in 2 methods in terms of capacity and deformation.

Plastic design of knee-element connection frames (KCFs) using mechanism control

In the past two decades, extensive research has been conducted to evaluate the seismic performance of Knee-element Connection Frames (KCFs) and to determine the most efficient configurations. KCFs are of particular advantage over other load-resisting systems in terms of their ample access for maintenance and enhanced structural performance. This paper presents an enhanced energy-based plastic design for KCFs using mechanism control. The design methodology developed in this study constitutes the design criteria employed in Performance-based Plastic Design (PBPD) and Theory of Plastic Mechanism Control (TPMC) at the same time. In this design approach, the external forces are derived from the energy balance equation directly considering second-order effects, and design is carried out according to the PBPD method. Then, undesired collapse mechanisms are identified and prevented by the use of a Design-Capacity Ratio-based (DCR-based) approach as the controlling criteria. To evaluate the design performance, nonlinear static and dynamic analyses were performed. The results indicate an acceptable correlation between the expected general yield mechanism and structural response and an acceptable economy in terms of material usage compared to comparable moment resisting frames.

Modified seismic design lateral force distribution for the Performance-Based Plastic Design (PBPD) of steel moment structures considering soil flexibility

It is well recognized that structures designed by conventional seismic design codes experience large inelastic deformations during strong ground motions. Realistic estimation of force distribution based on inelastic response is one of the important steps in a comprehensive seismic design methodology in order to represent expected structural response more accurately. This paper presents an extensive parametric study to investigate the structural damage distribution along the height of the steel moment-resisting frames (SMRFs) designed based on the stat-of-art constant-ductility performance-based plastic design (PBPD) approach considering soil flexibility effects when subjected to 20 strong ground motions. To this end, the effect of fundamental period, target ductility demand and base flexibility level are investigated and discussed. Based on the numerical results of this study, simplified equations are proposed for practical purpose to refine and modify the lateral force distribution pattern already suggested by researchers based on the study of inelastic behavior developed for fixed- and flexible-base structures by using relative distribution of maximum story shears of the selected structures subjected to various earthquake ground motions. It is demonstrated that the proposed equations can be adequately estimated the optimum values of shear proportioning factor for both fixed-based and soil-structure systems.

Seismic performance quantification of buckling-restrained braced RC frame structures under near-fault ground motions

The near-fault ground motion records with forward directivity (FS) and fling-step (FS) effects are characterized by the obvious velocity-pulses which will impose high seismic energy input to the building structures. The buckling-restrained braces (BRB) are one of the most commonly adopted lateral-force resisting and energy-dissipating components and BRBs are increasing configured in reinforced concrete (RC) frame structures to form a dual structural system (BRB-RCF). This paper presents the seismic performance quantification of BRB-RCFs subjected to near-fault ground motions with FD and FS effects. Suits of BRB-RCFs corresponding to different story numbers, BRB-resisted story shear ratios and BRB configuration types (single diagonal, inverted-V and V-type), were designed using the performance-based plastic design method. Three sets of 36 near-fault ground motions with FS, FD and non-pulse effects were selected. The seismic response including the maximum interstory drift ratio, floor acceleration, BRB ductility, BRB-resisted actual story shear ratio, etc., were investigated. Furthermore, the actual BRB-resisted story shear ratio was quantified and the design BRB-resisted story shear ratio was suggested. The analytical results can provide significant insights to the behavior quantification of BRB-RCFs when subjected to near-fault ground motions.

Performance of asmetric structures reviewed with based plastic design performance (case study of application on building in Pekan Baru)

Performance-Based Plastic Design (PBPD) is a structural analysis that can be used to review structural performance. This method is increasingly popular to be used in the earthquake-prone area. This method is based on energy method that can be applied to steel or concrete structures. Meanwhile, Indonesia has already SNI 1726:2102 to be used as a guide in designing the thrust load to review the level of structural performance. Both of these things need to be used as a reference in areas that were initially considered safe from the earthquake but based on the development of earthquake micro zonation maps, it is very possible to become potential areas that also become earthquake regions. For this reason, the case of the structure that was built in the Pekanbaru area was taken. From the analyses of structural behavior, the structure that applied PBPD has greater displacement than the structures that apply the thrust load of SNI 1726: 2012. The percentage of displacement that occurred was 8-37 %. Based on performance analysis, the structures according to PBPD shows a better level of performance to the application of SNI 1726: 2012 thrust load.

PERFORMANCE BASED SEISMIC DESIGN OF STRUCTURES – A REVIEW.

This paper presents an overview of the current state of knowledge with regard to literature on Performance based seismic design method. Performance-based earthquake engineering (PBEE) comprises the design, evaluation, and construction of structures performing during design earthquakes and extreme earthquakes to the desires / needs of owners, user, society and environment. The general promise of performance based design is to produce engineered structures with predictable performance during future earthquakes. Presented in this paper is an updated literature review of the Performance -based Seismic design (PBSD) method. Performance based Seismic design is an elastic design methodology done on the probable performance of the building under different ground motions. The derivatives of the PBSD method, known as the Performance ¬based Plastic design (PBPD) and Displacement-based seismic design (DBSD) method that has been widely recognized as an ideal method for use in the future practice of seismic design has also been reviewed.

Performance-based plastic design for seismic rehabilitation of high rise frames with eccentric bracing and vertical link

A large number of available concrete buildings designed only considering gravity load that require seismic rehabilitation because of failure to meet plasticity criteria. Using steel bracings are a common type of seismic rehabilitation. The eccentric bracings with vertical link reduce non-elastic deformation imposed on concrete members as well as elimination of probable buckling problems of bracings. In this study, three concrete frames of 10, 15, and 20 stories designed only for gravity load have been considered for seismic improvement using performance-based plastic design. Afterwards, nonlinear time series analysis was employed to evaluate seismic behavior of the models in two modes including before and after rehabilitation. The results revealed that shear link can yield desirable performance with the least time, cost and number of bracings of concrete frames. Also, it was found that the seismic rehabilitation can reduce maximum relative displacement in the middle stories about 40 to 80 percent. Generally, findings of this study demonstrated that the eccentric bracing with vertical link can be employed as a suitable proxy to achieve better seismic performance for existing high rise concrete frames.

Development of the Performance-Based Plastic Design Method by Considering the Effects of Aftershocks

ABSTRACT One of the efficient methods for seismic design of structures is Performance-based Plastic Design (PBPD) in which by choosing the desired yield mechanism and the target drift at the beginning of the design, unlike that in conventional design methods, there is no need for a time-consuming process of trial and error to achieve the desired performance. On the other hand, recent earthquakes have shown that aftershocks can increase the damage to a building after the main earthquake and thereby threaten the safety of the inhabitants. However, the seismic hazard of aftershocks is still not explicitly included in the current design codes. In this study, attempts have been made to develop the PBPD method for considering the effects of aftershocks. For this purpose, by performing an incremental dynamic analysis (IDA), the ductility factor μ and the ductility reduction factor Rμ of six PBPD frames (2-, 4-, 6-, 8-, 10-, and 12-story) were calculated under mainshock and mainshock-aftershock sequences. Then, the energy modification factor γ, which is related to the two parameters μ and Rμ, was calculated for both the mainshock and the mainshock-aftershock sequences. An equation is presented in order to calculate the ratio of the energy modification factor of the mainshock-aftershock sequence to the mainshock energy modification factor () according to the design period, and the factor obtained is multiplied by the energy modification factor γ so that the effect of aftershock can be considered for the frame design, and by using this modification, the performance of the frame under the mainshock-aftershock sequence can be improved. The results of the time-history analysis performed on the modified PBPD frames show better performance by the frames designed on the basis of modified PBPD than the frames designed on the basis of the original PBPD method under MS-AS sequences in terms of inter-story drift and rotation of plastic hinges.

Performance-based plastic design of composite partially-restrained steel frame-reinforced concrete infill walls with concealed vertical slits

In order to reasonably predict the seismic demand of composite partially-restrained steel frame-reinforced concrete (RC) infill walls with concealed vertical slits (PSRCW-CVS) subjected to the near-fault earthquake records with strong velocity-pulse effect, an innovative performance-based plastic design (PBPD) approach is developed in current study. The maximum effective cyclic energy (MECE), which can reflect this phenomenon that the structural dissipated input energy from near-fault pulse earthquake record commonly focuses on the largest yield excursion, is introduced and adopted as a new design indicator (ΔEh,max). The design base shear is determined according to the instantaneous energy balance concept and pre-selected desirable yield mechanism, which considers that the MECE demand obtained from MECE spectrum at target ductility ratio is equivalent to the instant energy supply from structural components. Additionally, the MECE calculating formula of each component of PSRCW-CVS structure is also provided. Four PSRCW-CVS illustrations (5-storey and 10-storey) with different target ductility ratio were designed according to the proposed PBPD methodology, and their seismic behaviors corresponding to the rare earthquake level were assessed through nonlinear time-history analysis method using the selected near-fault earthquake records with velocity-pulse effect. The analytical results show that four PSRCW-CVS structures can achieve the intended seismic behavior in terms of MECE, inter-story drift ratio, and residual inter-story drift ratio. The PSRCW-CVS structure exhibits the ideal progressively developed plastic mechanism. The reliability and reasonability of this PBPD method combined with MECE spectrum are verified, and it can be easily extended to other dual lateral load resisting systems.

Seismic Performance and Cost Comparison of Concentrically Braced Frames Designed By Performance-Based Plastic Design and Force-Based Design Method

Comparative study of 5, 10 and 15 storied steel Concentrically Braced Frames (CBF) designed by Performance Based Plastic Design (PBPD) method and Force Based Design (FBD) method is presented here. The parameters selected for comparison of the frames are (a) Lateral load distribution (b) Design sections of members (c) Seismic performance and (d) Cost. It is observed that the lateral load's distribution in case of PBPD frames is found more factual. The column sections of PBPD frames are heavier, and brace sections are lighter compared to FBD frames given the fact that PBPD is designed for higher ductility factor. The PBPD method gives a better seismic performance by achieving the predetermined failure mechanism and avoiding total collapse. Taller structures offer cost-effectiveness for PBPD method.

An improved performance-based plastic design method for seismic resilient fused high-rise buildings

The performance-based plastic design (PBPD) method generally relies on the nonlinear response of equivalent elastic-perfectly-plastic single degree of freedom system. It usually cannot achieve the design of three performance objectives simultaneously and may not consider the high mode effect of structure, which is significant for high-rise building. In this paper, a trilinear force-displacement model indicating three prescribed performance objectives at three seismic hazard levels is adopted to improve the PBPD method. The proposed improved PBPD method is derived based on multiple degrees of freedom system, while the high-mode effect and post-yield stiffness of the structure is considered. It can be used for designing seismic resilient fused high-rise buildings. A novel dual system composed of steel energy-dissipative column (EDC) and moment resisting frame (MF) is employed for application of the proposed method. This dual system has its fuse members decoupled from the gravity-resisting system, and the performance-based design of this system is discussed as well as its application for high-rise buildings. To demonstrate the effectiveness of the proposed method, a 20-story EDC-MF structure system is designed using the improved PBPD method. A detailed numerical model of the designed EDC-MF system is then built, and nonlinear dynamic response analyses at different seismic intensities are performed to verify the actual structure performance. Results show that the designed structure can achieve the prescribed yielding mechanism and performance objectives at three seismic hazard levels, and the EDC-MF system can be effectively applied to high-rise building as a seismic resilient fused structure.

Application of Performance-Based Plastic Design (PBPD) method for 3D steel structures

The Performance-Based Plastic Design (PBPD) method, introduced last decade, is an energy-based procedure. This method which is proposed for 2D frames has several stages. At the first stage, a pre-selected global yield mechanism and a target drift are selected. Then, the energy equilibrium equation is developed for a frame to calculate the base shear. At the end stage, designing the beams and columns is done for just one-bay of the planar frame. Since in PBPD-2D procedure the components of energy equilibrium equation are based on the planar frames, it does not consider the adjacent frames effect in 3D design problems so it is necessary to do research about developing PBPD method in 3D frames. The main scope of this paper is to apply the 3D effect on PBPD method. In the current research, the nonlinear distribution of base shear in plan has been found by nonlinear time-history analysis and processed by artificial neural networks. To fortify the results and analyses, 3D and nonlinear modeling is chosen. In the current research, the effect of earthquake power in the nonlinear base shear distribution in plan is considered by looking at the earthquake magnitude and the PGA. Since the earthquake energy is the best structural damage index, in this way, one can design 3D structures by PBPD method adjusted to the desired damage level. In this regards, three special moment frames are designed according to PBPD-2D procedure and proposed PBPD-3D procedure. The results of nonlinear time-history analysis show that the PBPD-2D method could not satisfy the weak beam- strong column criterion and the global yield mechanism in 3D designing, whereas the proposed method in this research, PBPD-3D, satisfies the mentioned criterion successfully.

Effects of soil‐structure interaction and lateral design load pattern on performance‐based plastic design of steel moment resisting frames

SummaryThe effects soil‐structure interaction (SSI) and lateral design load‐pattern are investigated on the seismic response of steel moment‐resisting frames (SMRFs) designed with a performance‐based plastic design (PBPD) method through a comprehensive analytical study on a series of 4‐, 8‐, 12‐, 14‐, and 16‐story models. The cone model is adopted to simulate SSI effects. A set of 20 strong earthquake records are used to examine the effects of different design parameters including fundamental period, design load‐pattern, target ductility, and base flexibility. It is shown that the lateral design load pattern can considerably affect the inelastic strength demands of SSI systems. The best design load patterns are then identified for the selected frames. Although SSI effects are usually ignored in the design of conventional structures, the results indicate that SSI can considerably influence the seismic performance of SMRFs. By increasing the base flexibility, the ductility demand in lower story levels decreases and the maximum demand shifts to the higher stories. The strength reduction factor of SMRFs also reduces by increasing the SSI effects, which implies the fixed‐base assumption may lead to underestimated designs for SSI systems. To address this issue, new ductility‐dependent strength reduction factors are proposed for multistory SMRFs with flexible base conditions.