Editorial

3 pages, 175 KiB

Open AccessEditorial

Special Issue on Advanced Methods for Seismic Performance Evaluation of Building Structures II

by Sang Whan Han

Appl. Sci. 2022, 12(7), 3505; https://doi.org/10.3390/app12073505 - 30 Mar 2022

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Earthquakes could be a hazard to human lives and the economy, leading to catastrophic disaster unless proper preparation is not made for buildings and infrastructures [...] Full article

(This article belongs to the Special Issue Advanced Methods for Seismic Performance Evaluation of Building Structures II)

Research

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18 pages, 6618 KiB

Open AccessArticle

A Soil-Dependent Approach for the Design of Novel Negative Stiffness Seismic Protection Devices

by Konstantinos A. Kapasakalis, Ioannis A. Antoniadis and Evangelos J. Sapountzakis

Appl. Sci. 2021, 11(14), 6295; https://doi.org/10.3390/app11146295 - 07 Jul 2021

Cited by 9 | Viewed by 1555

Abstract

Conventional base isolation (BI) techniques require a great reduction in the fundamental frequency of the system in order to mitigate the structural dynamic responses due to earthquake excitations. However, the resulting base displacements are large and can cause utility connection problems, rendering BI [...] Read more.

Conventional base isolation (BI) techniques require a great reduction in the fundamental frequency of the system in order to mitigate the structural dynamic responses due to earthquake excitations. However, the resulting base displacements are large and can cause utility connection problems, rendering BI inadequate for retrofitting. This paper proposes a vibration control system (VCS) that can be used as a supplement to the conventional BI to increase the effective damping, and thus reduce the required base displacements. A novel passive negative stiffness (NS)-based vibration absorber, based on the KDamper, is implemented in parallel to a BI. The design of the VCS follows a constrained optimization approach that accounts for geometrical and manufacturing limitations. The NS is realized with a realistic displacement-dependent mechanism that generates controlled NS. The VCS is designed for various soil-types in order to determine its effectiveness and soil-structure-interaction (SSI) effects are accounted with respect to the soil-type. The earthquake excitation input is selected according to the EC8 by generating a database of artificial accelerograms for each ground type. Finally, the VCS is compared to a conventional BI, and based on the numerical results obtained, the VCS is an effective alternative to BI and a possible retrofitting option. Full article

(This article belongs to the Special Issue Advanced Methods for Seismic Performance Evaluation of Building Structures II)

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18 pages, 6690 KiB

Open AccessArticle

Experimental Investigation into the Seismic Performance of Prefabricated Reinforced Masonry Shear Walls with Vertical Joint Connections

by Zhiming Zhang and Fenglai Wang

Appl. Sci. 2021, 11(10), 4421; https://doi.org/10.3390/app11104421 - 13 May 2021

Cited by 3 | Viewed by 1793

Abstract

In this study, four single-story reinforced masonry shear walls (RMSWs) (two prefabricated and two cast-in-place) under reversed cyclic loading were tested to evaluate their seismic performance. The aim of the study was to evaluate the shear behavior of RMSWs with flanges at the [...] Read more.

In this study, four single-story reinforced masonry shear walls (RMSWs) (two prefabricated and two cast-in-place) under reversed cyclic loading were tested to evaluate their seismic performance. The aim of the study was to evaluate the shear behavior of RMSWs with flanges at the wall ends as well as the effect of construction method. The test results showed that all specimens had a similar failure mode with diagonal cracking. However, the crack distribution was strongly influenced by the construction method. The lateral capacity of the prefabricated walls was 12% and 27% higher than that of the corresponding cast-in-place walls with respect to the rectangular and T-shaped cross sections. The prefabricated walls showed better post-cracking performance than did the cast-in-place wall. The secant stiffness of all the walls decreased rapidly to approximately 63% of the initial stiffness when the first major diagonal crack was observed. The idealized equivalent elastic-plastic system showed that the prefabricated walls had a greater displacement ductility of 3.2–4.8 than that of the cast-in-place walls with a displacement ductility value of 2.3–2.7. This proved that the vertical joints in prefabricated RMSWs enhanced the seismic performance of walls in shear capacity and ductility. In addition, the equivalent viscous damping of the specimens ranged from 0.13 to 0.26 for prefabricated and cast-in-place walls, respectively. Full article

(This article belongs to the Special Issue Advanced Methods for Seismic Performance Evaluation of Building Structures II)

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15 pages, 2507 KiB

Open AccessArticle

An Experimental Study on the Flexural Behavior of Precast Concrete Modular Beam Systems Using Inserted Steel Plates

by Kyong-Min Ro, Min-Sook Kim, Chang-Geun Cho and Young-Hak Lee

Appl. Sci. 2021, 11(9), 3931; https://doi.org/10.3390/app11093931 - 26 Apr 2021

Cited by 4 | Viewed by 2288

Abstract

Recently, interest in using precast concrete (PC) modules has increased due to their better seismic performance than steel modules. However, they must be joined by additional elements to ensure structural integration between the modules. The essential aim of the precast concrete module is [...] Read more.

Recently, interest in using precast concrete (PC) modules has increased due to their better seismic performance than steel modules. However, they must be joined by additional elements to ensure structural integration between the modules. The essential aim of the precast concrete module is to ensure structural performance with appropriate connection methods. However, the technical problem of connecting PC modules still needs to be improved. This study proposed a PC modular beam system for improved structural and splicing performance, and simple construction. This modular system consisted of modules with steel plates inserted to improve integrity of modules, ease of construction, and low cost. The structural performance of the proposed PC modular beam system was evaluated by flexural test on one reinforced concrete (RC) beam specimen consisting of a monolithic beam, and two PC specimens with the proposed modular system. The results demonstrated that the proposed PC modular beam system achieved approximately 80% of the structural performance compared to the monolithic specimen, with approximately 1.3-fold greater ductility. Full article

(This article belongs to the Special Issue Advanced Methods for Seismic Performance Evaluation of Building Structures II)

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22 pages, 7321 KiB

Open AccessArticle

Numerical Study of the Seismic Response of an Instrumented Building with Underground Stories

by Edmundo Schanze, Gilberto Leiva, Miguel Gómez and Alvaro Lopez

Appl. Sci. 2021, 11(7), 3190; https://doi.org/10.3390/app11073190 - 02 Apr 2021

Cited by 6 | Viewed by 1900

Abstract

Engineering practitioners do not usually include soil-structure interactions in building design; rather, it is common to model and design foundations as embedded joints with joint–based reactions. In some cases, foundation structures are modeled as rigid bodies, embedding the first story into lower vertical [...] Read more.

Engineering practitioners do not usually include soil-structure interactions in building design; rather, it is common to model and design foundations as embedded joints with joint–based reactions. In some cases, foundation structures are modeled as rigid bodies, embedding the first story into lower vertical elements. Given that the effects of underground floors on the seismic response are not generally included in current building design provisions, it has been little explored in the literature. This work compares and analyzes models to study the effects of different underground stories modeling approaches using earthquake vibration data recorded for the 16–story Alcazar building office in downtown Viña del Mar (Chile). The modeling expands beyond an embedded first story structure to soil with equivalent springs, representing soil-structure interaction (SSI), with varying rigid soil homogeneity. The building was modeled in a finite element software considering only dead load as a static load case because the structure remained in the framing stage when the monitoring system was operating. The instruments registered 72 aftershocks from the 2010 Maule Earthquake, and this study focused on 11 aftershocks of different hypocenters and magnitudes to collect representative information. The comparisons between empirical records and models in this study showed a better fit between the model and the real vibration data for the models that do consider the SSI using horizontal springs attached to the retaining walls of the underground stories. In addition, it was observed that applying a stiffness reduction factor of 0.7 to all elements in deformation verification models for average-height buildings was suitable to analyze the behavior under small earthquakes; better results are obtained embedding the structure in the foundation level than embedding in the street level; the use of horizontal springs with Kuesel’s model with traction for the analysis of the structure yields appropriate results; it is necessary to carefully select the spring constants to be used, paying special attention to the vertical springs. Even though the results presented herein indicate that the use of vertical springs to simulate the SSI of the base slab can result in major differences concerning the real response, it is necessary to obtain more data from instrumentation across a wider variety of structures to continue to evaluate better design and modeling practices. Similarly, further analyses, including nonlinear time-history and high-intensity events, are needed to best regulate building design. Full article

(This article belongs to the Special Issue Advanced Methods for Seismic Performance Evaluation of Building Structures II)

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20 pages, 20903 KiB

Open AccessArticle

Performance Evaluation of Rigid Braced Indirect Suspended Ceiling with Steel Panels

by Jae-Sub Lee, Dam-I Jung, Doo-Yong Lee and Bong-Ho Cho

Appl. Sci. 2021, 11(5), 1986; https://doi.org/10.3390/app11051986 - 24 Feb 2021

Cited by 4 | Viewed by 5363

Abstract

In Korea, the earthquakes in Gyeongju (2016) and Pohang (2017) have led to increased interest in the seismic design of nonstructural elements. Among these, the suspended ceiling can cause personal injury and property damage. In addition, most suspended ceilings that are used in [...] Read more.

In Korea, the earthquakes in Gyeongju (2016) and Pohang (2017) have led to increased interest in the seismic design of nonstructural elements. Among these, the suspended ceiling can cause personal injury and property damage. In addition, most suspended ceilings that are used in Korea neither have seismic design details nor meet the current seismic design standards. There are two seismic design methods for suspended ceilings using a perimeter clip and a brace. In the United States and Japan, seismic design of ceilings is typically used, but the concepts of applying and installing braces are different. This is because the typical ceiling systems are different in the United States and Japan. In this study, a brace-applied ceiling system that is suitable for a suspended ceiling with a steel panel was applied in the indirect suspended ceiling mainly used in Korea. In addition, the seismic performance was verified through a shaking table test. All the specimens were applied with anti-falling clips that are designed to prevent the panels from falling, and they satisfy KDS 41 17 00, which is a Korean seismic design life safety standard. Without considering these factors, the performance level is lower than a nonseismic designed ceiling, which is not properly designed or constructed. Full article

(This article belongs to the Special Issue Advanced Methods for Seismic Performance Evaluation of Building Structures II)

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16 pages, 4430 KiB

Open AccessArticle

A Study on the Dynamic Behavior of a Vertical Tunnel Shaft Embedded in Liquefiable Ground during Earthquakes

by Sun Yong Kwon and Mintaek Yoo

Appl. Sci. 2021, 11(4), 1560; https://doi.org/10.3390/app11041560 - 09 Feb 2021

Cited by 5 | Viewed by 1661

Abstract

Since liquefaction was first observed in South Korea during the Pohang earthquake, public concerns regarding the seismic stability of major infrastructure have increased substantially. However, the seismic behavior of tunnel shafts, which are an important element of tunnel structures, has not been properly [...] Read more.

Since liquefaction was first observed in South Korea during the Pohang earthquake, public concerns regarding the seismic stability of major infrastructure have increased substantially. However, the seismic behavior of tunnel shafts, which are an important element of tunnel structures, has not been properly established, especially under liquefiable soil conditions. In this study, 3D numerical modeling with Fast Lagrangian Analysis of Continua in 3 Dimensions (FLAC3D) was performed to predict the dynamic behavior of a vertical tunnel shaft during liquefaction. This study demonstrates key aspects of the dynamic behavior of tunnel shafts by varying important parameters such as the thickness of the liquefiable soil layer and applied seismicity level. Moreover, important dynamic responses such as excess pore pressure generation, the seismic bending moment of the shaft, and lateral displacements are highlighted. Finally, meaningful discussion of the seismic risk analysis based on damage indices is conducted based on the analysis results. Full article

(This article belongs to the Special Issue Advanced Methods for Seismic Performance Evaluation of Building Structures II)

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21 pages, 3550 KiB

Open AccessArticle

Intensity Measure Based on a Smooth Inelastic Peak Period for a More Effective Incremental Dynamic Analysis

by Juan Carlos Vielma, Maria Cristina Porcu and Nelson López

Appl. Sci. 2020, 10(23), 8632; https://doi.org/10.3390/app10238632 - 02 Dec 2020

Cited by 11 | Viewed by 2203

Abstract

The Incremental Dynamic Analysis (IDA) assesses the global collapse capacity of a structure by plotting its maximum inelastic response, obtained through a non-linear time-history analysis, versus the scaled intensity of different input earthquakes. The seismic intensity is often measured through the spectral acceleration [...] Read more.

The Incremental Dynamic Analysis (IDA) assesses the global collapse capacity of a structure by plotting its maximum inelastic response, obtained through a non-linear time-history analysis, versus the scaled intensity of different input earthquakes. The seismic intensity is often measured through the spectral acceleration at the fundamental elastic period. However, this can produce highly variable results. An alternative method is presented in this paper that relies on the elongated period, calculated either from the Fourier spectrum of the acceleration at a target building point (inelastic peak period) or from a smooth Fourier spectrum (inelastic smooth peak period). By referring to a reference reinforced concrete building and to a set of 10 spectrum-consistent earthquakes, the paper presents the results of a wide investigation. First, the variation in the elongated period as a function of the seismic intensity is discussed. Then, the effectiveness of the proposed method is assessed by comparing the IDA curves to those obtained through the elastic period or through approximate values of the elongated period given in the literature. The results show that the alternative IDA procedure generates curves with less-dispersed collapse thresholds. A statistical analysis shows significant improvements in the results when the inelastic smooth peak period is adopted. Full article

(This article belongs to the Special Issue Advanced Methods for Seismic Performance Evaluation of Building Structures II)

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