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21 pages, 9124 KiB

Open AccessArticle

Seismic Fragility Assessment of SMRFs Equipped with TMD Considering Cyclic Deterioration of Members and Nonlinear Geometry

by Mohammad Reza Hemmati Khollari, Azita Asadi and Hamed Tajammolian

Buildings 2023, 13(6), 1364; https://doi.org/10.3390/buildings13061364 - 23 May 2023

Viewed by 954

Abstract

This paper presents seismic fragility curves to assess the effect of far-field ground motions on the behavior of high-rise steel moment resisting frame (SMRF) structures equipped with Tuned Mass Damper, considering the cyclic deterioration of members and P-Delta effect in the nonlinear region. [...] Read more.

This paper presents seismic fragility curves to assess the effect of far-field ground motions on the behavior of high-rise steel moment resisting frame (SMRF) structures equipped with Tuned Mass Damper, considering the cyclic deterioration of members and P-Delta effect in the nonlinear region. For this purpose, three 8-, 20-, and 30-story SMRF structures are selected, 44 earthquake record sets are extracted from the FEMA P-695, Incremental Dynamic Analysis (IDA) is operated, and four structural damage states are considered through the framework of HAZUS, including slight, moderate, extensive, and complete. Maximum structural inter-story drift and floor acceleration are employed to quantify the damage states, and spectral acceleration is used as the intensity measure. Results show that the Tuned Mass Damper can reduce the probability of damage under earthquake excitation in all damage states for both structural and non-structural elements. The decline varies from 4.0% to 20.0%, depending on the ground motion intensity level, based on engineering demand parameters. Moreover, it is clear that nonlinear properties and component deterioration under cyclic excitation can affect structural response in all damage states, which concerns the obtained curves. Full article

(This article belongs to the Special Issue Seismic Performance Assessment and Analysis of Buildings Structures and Critical Infrastructure)

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28 pages, 9197 KiB

Open AccessArticle

Selection of Response Reduction Factor Considering Resilience Aspect

by S. Prasanth, Goutam Ghosh, Praveen Kumar Gupta, Virendra Kumar, Prabhu Paramasivam and Seshathiri Dhanasekaran

Buildings 2023, 13(3), 626; https://doi.org/10.3390/buildings13030626 - 27 Feb 2023

Cited by 9 | Viewed by 3088

Abstract

The selection of an adequate response reduction factor (R) in the seismic design of a reinforced concrete building is critical to the building’s seismic response. To construct a robust structure, the R factor should be chosen based on the building’s resilience performance. Since [...] Read more.

The selection of an adequate response reduction factor (R) in the seismic design of a reinforced concrete building is critical to the building’s seismic response. To construct a robust structure, the R factor should be chosen based on the building’s resilience performance. Since no background was provided for the selection of R factors, the study focuses on the right selection of R factors in relation to the building’s functionality, performance level, and resilience. In this study, a high-rise building with multiple R factors (R = 3, 4, 5, and 6) is developed. Five potential recovery paths (RP-1 to RP-5) that matched the realistic scenario were used to estimate the building’s functionality. The building was subjected to uni and bi-directional loadings, and two design levels, Design Basic Earthquake (DBE) and Maximum Considered Earthquake were used to monitor the building’s response. According to the findings, a decrease in the lateral design force with the highest R results in a high ductility requirement and a substantial loss of resilience. The maximum R factor can be recommended under uni-directional loading up to 6, in which the building’s resilience is almost 50%, whereas under bi-directional loading and taking the recommended R factor decreased from 6 to 4. Full article

(This article belongs to the Special Issue Seismic Performance Assessment and Analysis of Buildings Structures and Critical Infrastructure)

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21 pages, 6909 KiB

Open AccessArticle

Numerical Study Regarding the Seismic Response of a Moment-Resisting (MR) Reinforced Concrete (RC) Frame Structure with Reduced Cross-Sections of the RC Slabs

by Ion Sococol, Petru Mihai, Tudor-Cristian Petrescu, Florin Nedeff, Valentin Nedeff, Maricel Agop and Bogdan-Ionel Luca

Buildings 2022, 12(10), 1525; https://doi.org/10.3390/buildings12101525 - 23 Sep 2022

Cited by 1 | Viewed by 1426

Abstract

In the first part of the current study, the effectiveness of the transversal cross-section reduction method for RC beams in marginal areas (by means of mechanical drilling) was validated. The said method “encourages” the formation of plastic hinges at the beam ends and, [...] Read more.

In the first part of the current study, the effectiveness of the transversal cross-section reduction method for RC beams in marginal areas (by means of mechanical drilling) was validated. The said method “encourages” the formation of plastic hinges at the beam ends and, at the same time, allows for taking into account the bending stiffness of RC slabs, which is exerted upon the RC beams. In these conditions, the second part of the current research study (i.e., the current manuscript) highlights the real mode of reducing the lateral stiffness of the slabs upon the RC beams. These elements form a common body, together with the beam–column frame node. The same method as in the first part of the study—“weakening” the plates in the corner area through vertical drilling, without affecting the integrity of the reinforcing elements—was used. The analytical MR RC frame model, studied by means of the comparative method, highlights the efficiency of the transversal cross-section reduction method for RC slabs. Basically, the directing of the plastic deformations from the weakened slab areas towards the marginal areas of the reinforced concrete beams takes place. The beams rotate as far as the weakened slab areas allow its plastic deformation, thus being possible to observe the partial conservation effect of the beam–column frame joint. Furthermore, for the analytical model with the maximum number of vertical holes in the corner areas of the concrete plate, minimal plastic deformations are recorded for the marginal areas of the concrete columns. A partial conservation of the formation mechanism of the “beam-slab-frame node” common rigid block is also noted. Consequently, the dissipation of the seismic energy is made in a partially controlled and directed manner, in the “desired” areas, according to the “Strong Columns—Weak Beams” (SCWB) ductile mechanism of the lateral behavior to seismic actions for reinforced concrete frame structures. The mechanism is specified in current design norms for RC frame systems. The effectiveness of the method for reducing the transversal section of the RC plates in the corner areas by means of transversal drilling is highlighted and validated from the perspective of the local and global ductile seismic response of reinforced concrete frame structures. A significant reduction in the bending stiffness of the slabs upon the beams and a real development of the plastic hinges in the marginal areas of the beams (together with partial implications and plastic deformations) were observed. Full article

(This article belongs to the Special Issue Seismic Performance Assessment and Analysis of Buildings Structures and Critical Infrastructure)

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22 pages, 6333 KiB

Open AccessArticle

Seismic Performance of a Novel Precast Beam-Column Joint Using Shape Memory Alloy Fibers-Reinforced Engineered Cementitious Composites

by Weihong Chen, Kai Feng, Ying Wang, Shuangshuang Cui and Yiwang Lin

Buildings 2022, 12(9), 1404; https://doi.org/10.3390/buildings12091404 - 07 Sep 2022

Cited by 5 | Viewed by 1898

Abstract

A novel precast beam–column joint using shape memory alloy fibers-reinforced engineered cementitious composites (SMA-ECC) was proposed in this study to achieve self-repairing of cracks and internal damage after an earthquake. Three large-scale beam–column joints were tested under displacement reversals, including one monolithically cast [...] Read more.

A novel precast beam–column joint using shape memory alloy fibers-reinforced engineered cementitious composites (SMA-ECC) was proposed in this study to achieve self-repairing of cracks and internal damage after an earthquake. Three large-scale beam–column joints were tested under displacement reversals, including one monolithically cast conventional concrete joint, one engineered cementitious composites (ECC) reinforced precast concrete joint, and one SMA-ECC reinforced precast concrete joint. Failure mode, crack pattern, hysteretic behavior, stiffness degradation, displacement ductility, and energy dissipation capacity were compared and evaluated through a cyclic loading test. The test results showed that the ECC-based (ECC, SMA-ECC) precast joints have equivalent seismic properties to the monolithically cast concrete joint. ECC-based joints enhanced the ductility and energy dissipation capacity of the joint and, remarkably, reduced crack width. The SMA-ECC reinforced joint also exhibited instant self-healing in terms of the closure of small cracks after unloading. The self-healing performance was further evaluated through ultrasonic pulse tests, with the results showing that the use of SMA-ECC material was efficient in reducing the internal damage of beam–column joints after an earthquake. Full article

(This article belongs to the Special Issue Seismic Performance Assessment and Analysis of Buildings Structures and Critical Infrastructure)

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32 pages, 9191 KiB

Open AccessArticle

Analytical Study Regarding the Seismic Response of a Moment-Resisting (MR) Reinforced Concrete (RC) Frame System with Reduced Cross Sections of the RC Beams

by Ion Sococol, Petru Mihai, Tudor-Cristian Petrescu, Florin Nedeff, Valentin Nedeff and Maricel Agop

Buildings 2022, 12(7), 983; https://doi.org/10.3390/buildings12070983 - 11 Jul 2022

Cited by 4 | Viewed by 1888

Abstract

In the last few decades, a series of earthquakes were recorded which pointed out several deficiencies regarding the ductile seismic response of MR RC frame structures. Thus, the research problem centres around the failure mechanisms registered by the structures, which differ from the [...] Read more.

In the last few decades, a series of earthquakes were recorded which pointed out several deficiencies regarding the ductile seismic response of MR RC frame structures. Thus, the research problem centres around the failure mechanisms registered by the structures, which differ from the general notions of seismic response commonly found in current design standards and norms regarding seismic actions. In these conditions, in the present paper—by using comparative methods—the analytical validation of the solution of plastic hinge concentration and seismic energy dissipation in the marginal beam areas is proposed. Therefore, the RC beam sections were reduced (weakened) in the marginal areas which exhibit a plastic deformation potential, as well as in the corner areas of concrete slabs with vertical rectangular holes. The significant outcomes of this research imply the partial “guiding” of plastic hinges in the zones adjacent to beam ends. Furthermore, a reduction of both the negative effects of horizontal rigidization of the beams and the cracking and plastic deformation effects of beam-column frame joints was observed. With these technical implications, a complex mechanism of plastic deformation of MR RC frame models is registered in which all lateral elements (including RC columns) participate in the dissipation of seismic energy, without the occurrence of the “weak storey” mechanism for any of the analytical RC frame models. Furthermore, it is possible to observe the partial formation of the global plastic mechanism “Strong Columns—Weak Beams” (SCWB) for some of the structural models. Finally, the analytically studied innovative element regarding the improvement of the seismic response of pure MR RC frame structures is successfully validated. Full article

(This article belongs to the Special Issue Seismic Performance Assessment and Analysis of Buildings Structures and Critical Infrastructure)

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20 pages, 6699 KiB

Open AccessArticle

Some Issues in the Seismic Assessment of Shear-Wall Buildings through Code-Compliant Dynamic Analyses

by Maria Cristina Porcu, Juan Carlos Vielma Pérez, Gavino Pais, Diego Osorio Bravo and Juan Carlos Vielma Quintero

Buildings 2022, 12(5), 694; https://doi.org/10.3390/buildings12050694 - 23 May 2022

Cited by 6 | Viewed by 2595

Abstract

Due to their excellent seismic behavior, shear wall-type concrete buildings are very popular in earthquake-prone countries like Chile. According to current seismic regulations, the performance of such structures can be indifferently assessed through linear or non-linear methods of analysis. Although all the code-compliant [...] Read more.

Due to their excellent seismic behavior, shear wall-type concrete buildings are very popular in earthquake-prone countries like Chile. According to current seismic regulations, the performance of such structures can be indifferently assessed through linear or non-linear methods of analysis. Although all the code-compliant approaches supposedly lead to a safe design, linear approaches may be in fact less precise for catching the actual seismic performance of ductile and dissipative structures, which can even result in unconservative design where comparatively stiff buildings like reinforced-concrete shear-wall (RC-SW) buildings are concerned. By referring to a mid-rise multistory RC-SW building built in Chile and designed according to the current seismic Chilean code, the paper investigates the effectiveness of the linear dynamic analyses to predict the seismic performance of such kind of structures. The findings show that the code-compliant linear approaches (Modal Response Spectrum Analysis and Linear Time-History Analysis) may significantly underestimate the displacement demand in RC-SW buildings. This is highlighted by the comparison with the results obtained from the Non-Linear Time-History Analysis, which is expected to give more realistic results. A set of ten spectrum-consistent Chilean earthquakes was considered to carry out the time-history analyses while a distributed-plasticity fiber-based approach was adopted to model the non-linear behavior of the considered building. The paper highlights how the risk of an unsafe design may become higher when reference is made to the Chilean code, the latter considering only the Modal Response Spectrum Analysis (MRSA) without even providing corrective factors to estimate the inelastic displacement demand. The paper checks the effectiveness of some amplifying factors taken from the literature with reference to the case-study shear-wall building, concluding that they are not effective enough. The paper also warns against the danger of local soft-story collapse mechanisms, which are typical of reinforced concrete frames but may also affect RC-SW buildings when weaker structural parts made by column-like walls are present at the ground floor. Full article

(This article belongs to the Special Issue Seismic Performance Assessment and Analysis of Buildings Structures and Critical Infrastructure)

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14 pages, 6055 KiB

Open AccessArticle

Seismic Risk Assessment for Elements of the Electric Network in Romania

by Florin Pavel and Radu Vacareanu

Buildings 2022, 12(2), 244; https://doi.org/10.3390/buildings12020244 - 19 Feb 2022

Cited by 2 | Viewed by 1831

Abstract

This study is focused on the assessment of the seismic risk for elements of the electric network (thermoelectric powerplants and substations) in Romania. Firstly, the main elements of the electric network analyzed in this study are briefly presented. Thermoelectric powerplants account for about [...] Read more.

This study is focused on the assessment of the seismic risk for elements of the electric network (thermoelectric powerplants and substations) in Romania. Firstly, the main elements of the electric network analyzed in this study are briefly presented. Thermoelectric powerplants account for about 30% of the electricity production capacity and for about 40% of electricity production. The damage to the electric network in Romania caused by the Vrancea 1977 seismic event is presented in this study. The seismic fragility of thermoelectric powerplants as recommended by the SYNER-G project is evaluated in relation to the damage observed after the Vrancea intermediate-depth earthquake of March 1977. The impact of anchoring the components of substations and of powerplants on the seismic risk metrics is also evaluated using fragility parameters from the literature. The analyses show that the impact of anchoring the components on the seismic risk metrics is less important for substations than for thermoelectric powerplants. In addition, it was observed that the level of seismic risk is larger in the case of electric substations as compared to powerplants. Full article

(This article belongs to the Special Issue Seismic Performance Assessment and Analysis of Buildings Structures and Critical Infrastructure)

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Review

Jump to: Research

12 pages, 278 KiB

Open AccessFeature PaperReview

Review of Methodologies for Displacement Checks in Modern Seismic Design Codes

by Florin Pavel and Radu Vacareanu

Buildings 2023, 13(4), 940; https://doi.org/10.3390/buildings13040940 - 02 Apr 2023

Cited by 2 | Viewed by 1716

Abstract

This review paper discusses the procedures for evaluating the design displacement given in various design codes from seismically prone countries around the world (the United States, New Zealand, Chile, Japan, Greece, Italy, Iran, India, Turkey, and Romania). The limit displacements and the corresponding [...] Read more.

This review paper discusses the procedures for evaluating the design displacement given in various design codes from seismically prone countries around the world (the United States, New Zealand, Chile, Japan, Greece, Italy, Iran, India, Turkey, and Romania). The limit displacements and the corresponding limit states are also presented and analyzed in this study besides the importance class factors considered in the selected seismic design codes. A presentation of the behavior factors necessary for evaluating the design value of the seismic action is also shown in this study. One of the observations of this review paper is that there are significant similarities in terms of the approach to the displacement check in the analyzed codes. In addition, it was observed that the displacement check is generally associated with the serviceability limit state (e.g., damage limitation). However, differences in terms of the mean return period for the serviceability check action were observed among the analyzed seismic design codes. Several aspects which have to be further adapted in the future versions of seismic design codes are also discussed in this review paper. One of the main aspects which must be further discussed is the enforcement of displacement limits, which are dependent on the structural system and on the importance of the class/height regime for the ultimate/serviceability limit state. In addition, the dependence of the T_D control period on the probabilistic seismic hazard ordinates should be further discussed. Moreover, the pulse effects, which can affect both the acceleration and the displacement design of response spectra, should be accounted for as well in future generations of seismic codes. Finally, it appears necessary to perform a harmonization of the behavior factors employed in seismic design codes. Full article

(This article belongs to the Special Issue Seismic Performance Assessment and Analysis of Buildings Structures and Critical Infrastructure)

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