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18 pages, 4227 KiB

Open AccessArticle

Seismic Response of a Structure Equipped with an External Viscous Damping System

by Antonio Sabino, Antonio Mannella and Andrea Matteo de Leo

Buildings 2020, 10(2), 19; https://doi.org/10.3390/buildings10020019 - 22 Jan 2020

Cited by 4 | Viewed by 3532

The aim of this research is to evaluate the effectiveness of a seismic retrofit technique that involves the introduction of energy dissipation devices properly connected to an existing structure through a system of cables and levers, which are employed to amplify total or [...] Read more.

The aim of this research is to evaluate the effectiveness of a seismic retrofit technique that involves the introduction of energy dissipation devices properly connected to an existing structure through a system of cables and levers, which are employed to amplify total or inter-story drift at device end. One of the main topics related to the introduction of energy dissipation devices, lies in the choice of their optimal setting within the structure to maximize the effectiveness without producing functionality limitations. The achievement of these objectives is, therefore, linked, regardless of the type adopted, to the amount of energy dissipated in each cycle, directly proportional to the displacement magnitude to which the device is subject. Many configurations proposed in the literature and currently adopted in professional practice provide additional dissipation systems variously connected to braces installed inside the structural frame and, therefore, able to exploit the inter-story drift produced by seismic input. The proposed system exploits top displacements of the structure with respect to the foundation level, transferred to the device through a system of cables properly configured and amplified with leverage. This paper represents the first step of the research, in which simple single degree of freedom (SDOF) or two degrees of freedom (2-DOF) models are taken into account to evaluate the effects of the introduction of the proposed system in terms of reducing the seismic demand on the structure, proceeding to a parametric analysis to obtain initial indications for the design of the system in relation to the geometric and inertial characteristics of the original structure. Full article

(This article belongs to the Special Issue Smart Solutions and Structural Systems for Seismic-Resistant Buildings)

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20 pages, 490 KiB

Open AccessArticle

An Optimal Seismic Force Pattern for Uniform Drift Distribution

by Rosario Montuori, Elide Nastri and Bonaventura Tagliafierro

Buildings 2019, 9(11), 231; https://doi.org/10.3390/buildings9110231 - 06 Nov 2019

Cited by 17 | Viewed by 4832

Abstract

The force distribution proposed by codes, which in many cases is framed in the equivalent static force procedure, likely leads to design structures with non-uniform drift distribution in terms of inter-storey drift and ductility demands. This can lead to an unbalanced drift demand [...] Read more.

The force distribution proposed by codes, which in many cases is framed in the equivalent static force procedure, likely leads to design structures with non-uniform drift distribution in terms of inter-storey drift and ductility demands. This can lead to an unbalanced drift demand at certain storeys. This phenomenon may also amass cyclic damage to the dissipative elements at this very storey, therefore increasing the probability of premature failure for low-cycle fatigue. This work proposes a new force design distribution that accounts for higher mode effects and limits the displacement concentration at any storey thus improving the dissipative capacity of the whole structures. The main advantage of the proposed method stands in its formulation, which allows to spare any previous set up with structural analyses. The proposed force distribution has been applied to multi-degree-of-freedom systems to check its effectiveness, and the results have been compared with other proposals. In addition, in order to obtain a further validation of the proposed force distribution, the results obtained by using a genetic algorithm have been evaluated and compared. Additionally, the results provided in this work validate the proposed procedure to develop a more efficient lateral load pattern. Full article

(This article belongs to the Special Issue Smart Solutions and Structural Systems for Seismic-Resistant Buildings)

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16 pages, 5218 KiB

Open AccessArticle

Earthquake Response of Cold-Formed Steel-Based Building Systems: An Overview of the Current State of the Art

by Gianmaria Di Lorenzo and Attilio De Martino

Buildings 2019, 9(11), 228; https://doi.org/10.3390/buildings9110228 - 31 Oct 2019

Cited by 6 | Viewed by 7880

Abstract

Building systems fabricated with cold-formed steel (CFS) profiles and members made of wood, gypsum, or other materials allow solving a range of issues arising in common constructional elements thanks to their advantages, such as lightness, strength, durability, physical stability, sustainability, and cost-effectiveness. As [...] Read more.

Building systems fabricated with cold-formed steel (CFS) profiles and members made of wood, gypsum, or other materials allow solving a range of issues arising in common constructional elements thanks to their advantages, such as lightness, strength, durability, physical stability, sustainability, and cost-effectiveness. As a result of this inherent competitiveness of CFS based buildings, their use has been gradually increasing in recent years both in the field of structural systems as non-structural architectural components and, above all, in the area of earthquake resistant buildings, where lightness play a key role. After a general introduction, the paper gives an overview of the current codification and ongoing research on CFS non-structural architectural and structural systems. Finally, the main conclusions are summarised, and possible future developments are outlined. Full article

(This article belongs to the Special Issue Smart Solutions and Structural Systems for Seismic-Resistant Buildings)

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26 pages, 13176 KiB

Open AccessArticle

Prediction of the Maximum Seismic Member Force in a Superstructure of a Base-Isolated Frame Building by Using Pushover Analysis

by Kenji Fujii

Buildings 2019, 9(9), 201; https://doi.org/10.3390/buildings9090201 - 05 Sep 2019

Cited by 4 | Viewed by 3990

Abstract

It is essential for the seismic design of a base-isolated building that the seismic response of the superstructure remains within the elastic range. The evaluation of the maximum seismic member force in a superstructure is thus an important issue. The present study predicts [...] Read more.

It is essential for the seismic design of a base-isolated building that the seismic response of the superstructure remains within the elastic range. The evaluation of the maximum seismic member force in a superstructure is thus an important issue. The present study predicts the maximum seismic member force of five- and fourteen-story reinforced concrete base-isolated frame buildings adopting pushover analysis. In the first stage of the study, the nonlinear dynamic (time-history) analysis of the base-isolated frame buildings is carried out, and the nonlinear modal responses of the first and second modes are calculated from pushover analysis results. In the second stage, a set of pushover analyses is proposed considering the combination of the first and second modal responses, and predicted maximum member forces are compared with the nonlinear time-history analysis results. Results show that the maximum member forces predicted in the proposed set of pushover analyses are satisfactorily accurate, while the results predicted considering only the first mode are inaccurate. Full article

(This article belongs to the Special Issue Smart Solutions and Structural Systems for Seismic-Resistant Buildings)

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15 pages, 4232 KiB

Open AccessArticle

Seismic Behaviour of EC8-Compliant Moment Resisting and Concentrically Braced Frames

by Silvia Costanzo, Roberto Tartaglia, Gianmaria Di Lorenzo and Attilio De Martino

Buildings 2019, 9(9), 196; https://doi.org/10.3390/buildings9090196 - 28 Aug 2019

Cited by 23 | Viewed by 4659

Abstract

The design procedure codified within current Eurocode 8 for dissipative moment resisting and concentrically braced frames have led to the design of massive systems characterized in the most of cases by poor energy dissipation capacity. The research activity presented in the current paper [...] Read more.

The design procedure codified within current Eurocode 8 for dissipative moment resisting and concentrically braced frames have led to the design of massive systems characterized in the most of cases by poor energy dissipation capacity. The research activity presented in the current paper addresses the identification of the main criticisms and fallacies in the current EN 1998-1 for those seismic-resistant typologies. In this regard, the design provisions and codified rules for both moment resisting frames (MRFs) and chevron concentrically braced frames (CCBFs) are critically discussed and numerically investigated. Static and incremental dynamic analyses were performed on a set of 3 and 6-story frames designed compliant to EN 1998-1. The results from the numerical analyses are reported and discussed. Full article

(This article belongs to the Special Issue Smart Solutions and Structural Systems for Seismic-Resistant Buildings)

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37 pages, 16369 KiB

Open AccessArticle

Pushover-Based Seismic Capacity Evaluation of Uto City Hall Damaged by the 2016 Kumamoto Earthquake

by Kenji Fujii

Buildings 2019, 9(6), 140; https://doi.org/10.3390/buildings9060140 - 05 Jun 2019

Cited by 9 | Viewed by 5482 | Correction

Abstract

The seismic capacity of the main Uto City Hall building, which was severely damaged by the 2016 Kumamoto Earthquake, was evaluated by the proposed pushover-based procedure. In this procedure, the seismic capacity index of the building is defined as the maximum scaling factor [...] Read more.

The seismic capacity of the main Uto City Hall building, which was severely damaged by the 2016 Kumamoto Earthquake, was evaluated by the proposed pushover-based procedure. In this procedure, the seismic capacity index of the building is defined as the maximum scaling factor of the seismic input, for which the local responses do not exceed their limit values. From the pushover analysis result, the displacement limit of the equivalent single-degree-of-freedom model was determined. Then, the seismic capacity index was evaluated using an equivalent linearization technique. The evaluated index was re-evaluated by considering the bidirectional excitation. The pushover analysis result revealed that the torsional response is significant in the nonlinear behavior of this building. The evaluated seismic capacity implied that some structural damages, including the yielding of the beam-column joint, may have occurred during the first earthquake on 14 April 2016. Full article

(This article belongs to the Special Issue Smart Solutions and Structural Systems for Seismic-Resistant Buildings)

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22 pages, 3202 KiB

Open AccessArticle

Proposed Simplified Approach for the Seismic Analysis of Multi-Storey Moment Resisting Framed Buildings Incorporating Friction Sliders

by Shahab Ramhormozian, G. Charles Clifton, Massimo Latour and Gregory A. MacRae

Buildings 2019, 9(5), 130; https://doi.org/10.3390/buildings9050130 - 23 May 2019

Cited by 15 | Viewed by 5580

Abstract

An innovative, simplified, and accurate model is proposed and developed to enable simplified yet realistic time history analysis of multi-storey buildings with moment resisting connections using friction energy dissipaters in the commonly used structural analysis and design program, SAP2000. The analyses are rapid [...] Read more.

An innovative, simplified, and accurate model is proposed and developed to enable simplified yet realistic time history analysis of multi-storey buildings with moment resisting connections using friction energy dissipaters in the commonly used structural analysis and design program, SAP2000. The analyses are rapid to undertake, thereby enabling detailed study of the influence of many building system effects on the overall response. This paper presents the outcome of dynamic analysis of a complete 13-storey moment resisting steel building with Sliding Hinge Joints as the beam-column connections, considering the influential self-centring factors such as MRF and gravity columns continuity as well as column base and diaphragm flexibilities. The building is one of the Te-Puni towers, which are structural steel apartment buildings with steel-concrete composite floors, designed according to the low damage design philosophy, built in Wellington, New Zealand in 2008 and which have already been subjected to two significant earthquakes. The key objectives of the research have been to take the design of the 13-storey building and convert that into the proposed simplified model required for time history seismic analysis, to undertake analysis under scaled El-Centro earthquake record, investigate the peak inter-storey drift and the residual drift of the building, and determine the influence of column base rotational stiffness, floor slab out of horizontal plane displacement, type of friction damper, and MRF and gravity column continuity. It is concluded that the response of the building is stable and predictable, as expected, and that the post-earthquake state of the building, particularly from the self-centring point of view, is well within the limits for maintaining operational continuity following an ULS level design earthquake. Full article

(This article belongs to the Special Issue Smart Solutions and Structural Systems for Seismic-Resistant Buildings)

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10 pages, 3407 KiB

Open AccessArticle

Incremental Dynamic Analysis for Estimating Seismic Performance of Multi-Story Buildings with Butterfly-Shaped Structural Dampers

by Alireza Farzampour, Iman Mansouri and Hamzeh Dehghani

Buildings 2019, 9(4), 78; https://doi.org/10.3390/buildings9040078 - 08 Apr 2019

Cited by 20 | Viewed by 5758

Abstract

Structural strength and stiffness were previously investigated to sufficiently improve the lateral load resistance against major events. Many buildings require appropriate design to effectively withstand the lateral seismic loads and reduce the corresponding damages. Design methodologies and structural elements were recently introduced to [...] Read more.

Structural strength and stiffness were previously investigated to sufficiently improve the lateral load resistance against major events. Many buildings require appropriate design to effectively withstand the lateral seismic loads and reduce the corresponding damages. Design methodologies and structural elements were recently introduced to improve the energy dissipation capability and limit the high force demands under seismic loadings. The new systems are designed to protect the structural integrity and concentrate the inelasticity in a specific area, while the remaining parts are kept undamaged and intact. This study introduces a new structural system with dampers having strategic cutouts, leaving butterfly-shaped shear dampers for dominating the yielding mechanism over other brittle limit states. The new system is designed for re-establishing the conventional eccentrically braced frame system with simple linking beams. The system with strategic cutouts is subsequently used and compared with the eccentrically braced frames (EBF) system for seismic performance investigation and incremental dynamic analysis (IDA), using the OpenSees program, which is used to indicate the collapse behavior under forty-four selected ground motions. Results show that the butterfly-shaped multi-story buildings, compared to the corresponding conventional systems, are capable of enhancing the system resistance against lateral seismic loads by postponing the collapse state to the larger drift ratio values. Full article

(This article belongs to the Special Issue Smart Solutions and Structural Systems for Seismic-Resistant Buildings)

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