scholarly journals PRELIMINARY NUMERICAL ANALYSIS OF THE SEISMIC RESPONSE OF STEEL FRAMES WITH MASONRY INFILLS RETROFITTED BY BUCKLING RESTRAINED BRACES

2021 ◽  
Author(s):  
Fernando Gutiérrez-Urzúa ◽  
Fabio Freddi ◽  
Luigi Di Sarno ◽  
Jing-Ren Wu ◽  
Mario D’Aniello ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Seismic Response ◽  
Steel Frames ◽  
Masonry Infills ◽  
Buckling Restrained Braces

scholarly journals Fragility assessment of existing low-rise steel moment-resisting frames with masonry infills under mainshock-aftershock earthquake sequences

2021 ◽  
Vol 19 (6) ◽  
pp. 2483-2504
Author(s):  
Luigi Di Sarno ◽  
Jing-Ren Wu
Keyword(s):  
Seismic Vulnerability ◽  
Steel Frames ◽  
Steel Frame ◽  
Second Phase ◽  
Moment Frames ◽  
Damage Level ◽  
Masonry Infills ◽  
Aftershock Sequences ◽  
The Impact ◽  
Multiple Earthquakes

AbstractThis paper presents the fragility assessment of non-seismically designed steel moment frames with masonry infills. The assessment considered the effects of multiple earthquakes on the damage accumulation of steel frames, which is an essential part of modern performance-based earthquake engineering. Effects of aftershocks are particularly important when examining damaged buildings and making post-quake decisions, such as tagging and retrofit strategy. The procedure proposed in the present work includes two phase assessment, which is based on incremental dynamic analyses of two refined numerical models of the case-study steel frame, i.e. with and without masonry infills, and utilises mainshock-aftershock sequences of natural earthquake records. The first phase focuses on the undamaged structure subjected to single and multiple earthquakes; the effects of masonry infills on the seismic vulnerability of the steel frame were also considered. In the second phase, aftershock fragility curves were derived to investigate the seismic vulnerability of infilled steel frames with post-mainshock damage caused by mainshocks. Comparative analyses were conducted among the mainshock-damaged structures considering three post-mainshock damage levels, including no damage. The impact of aftershocks was then discussed for each mainshock-damage level in terms of the breakpoint that marks the onset of exceeding post-mainshock damage level, as well as the probability of exceeding of superior damage level due to more significant aftershocks. The evaluation of the efficiency of commonly used intensity measures of aftershocks was also carried out as part of the second phase of assessment.

Numerical analysis of the out-of-plane response of two systems for masonry infills

2016 ◽  
pp. 1179-1184 ◽  
Author(s):  
A. Drougkas ◽  
C.-E. Adami ◽  
E. Vintzileou ◽  
V. Palieraki
Keyword(s):  
Numerical Analysis ◽  
Masonry Infills ◽  
Two Systems ◽  
Out Of Plane

Influence of masonry infills on seismic response of RC frames under low frequency cyclic load

2019 ◽  
Vol 183 ◽  
pp. 70-82 ◽  
Author(s):  
Ning Ning ◽  
Zhongguo John Ma ◽  
Pengpeng Zhang ◽  
Dehu Yu ◽  
Jianlang Wang
Keyword(s):  
Seismic Response ◽  
Cyclic Load ◽  
Low Frequency ◽  
Masonry Infills ◽  
Rc Frames

scholarly journals Irregularity Effects of Masonry Infills on Nonlinear Seismic Behaviour of RC Buildings

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Massimiliano Ferraioli ◽  
Angelo Lavino
Keyword(s):  
Seismic Response ◽  
Seismic Vulnerability ◽  
Eurocode 8 ◽  
Seismic Action ◽  
Rc Buildings ◽  
Infill Walls ◽  
Nonstructural Components ◽  
Action Effects ◽  
Masonry Infills ◽  
Shear Demand

Despite extensive research studies, the seismic response of infilled reinforced concrete buildings remains an open problem due to both the complexity of the interaction between the infill and the frame and the large number of parameters involved. Thus, guidelines for both modelling and analysis are still lacking and the infill walls are normally treated as nonstructural components in seismic codes. However, it may be not conservative to neglect the influence of infills. In fact, the infill masonry walls may significantly affect the stiffness, strength, and energy dissipation capacity of RC buildings, even when they are regularly distributed. Recognizing this influence and its importance on the vulnerability of infilled frames, Eurocode 8 requires amplifying seismic action effects due to infills. In this paper, the effectiveness of the Eurocode 8 design provisions for infill irregularity in plan and/or elevation was investigated. To this aim, different in-plan layouts of infill walls were selected as marginal cases for which Eurocode 8 does not require amplification of the action effects due to the presence of infills, or the additional measures to counteract these effects are not mandatory. The seismic vulnerability of the infilled RC buildings was evaluated using nonlinear static and nonlinear dynamic analyses. Both cracking and crushing of masonry and stiffness and strength degradation were considered in the analysis. The effect of the layout of the masonry infills on the seismic response in terms of resistance and displacement was evaluated. Results show that in one of the case studies here examined, it is not conservative to neglect the influence of infill panels. In fact, structural failure due to torsion and soft-storey effects may occur even in cases where Eurocode 8 does not require the amplification of the action effects. Finally, the total shear demand on columns may be underestimated, even in cases where the code provisions for infills irregularity are not mandatory, and the additional shear demand in the columns induced by the masonry infill is very low.

scholarly journals Seismic Response Analysis of Multi-Story Steel Frames Using BRB and SCB Hybrid Bracing System

2019 ◽  
Vol 10 (1) ◽  
pp. 284 ◽  
Author(s):  
Rong Chen ◽  
Canxing Qiu ◽  
Dongxue Hao
Keyword(s):  
Seismic Response ◽  
Seismic Analysis ◽  
Steel Frames ◽  
Residual Deformation ◽  
High Energy ◽  
Response Analysis ◽  
Building Structures ◽  
Seismic Capacity ◽  
Story Drift ◽  
Bracing System

Multi-story steel frames are popular building structures. For those with insufficient seismic resistance, their seismic capacity can be improved by installing buckling-restrained braces (BRBs), which is known for high energy dissipation capacity, and the corresponding frame is denoted as BRB frame (BRBF). However, BRBFs are frequently criticized because of excessive residual deformations after earthquakes, which impede the post-event repairing work and immediate occupancy. Meanwhile, self-centering braces (SCBs), which were invented with a particular purpose of eliminating residual deformation for the protected structures, underwent fast development in recent years. However, the damping capability of SCBs is relatively small because their hysteresis is characterized by a flag shape. Therefore, this paper aims to combine these two different braces to form a hybrid bracing system. A total of four combinations are proposed to seek an optimal solution. The multi-story steel frames installed with BRBs, SCBs, and combined braces are numerically investigated through nonlinear static and dynamic analyses. Interested seismic response parameters refer to the maximum story drift ratios, maximum floor accelerations, and residual story drift ratios. The seismic analysis results indicate that the frames using the combined bracing system are able to take the advantages of BRBs and SCBs.

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