Simplified evaluation of drifts for RC buildings with masonry infills

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.

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Response of Mid-Rise Reinforced Concrete Frame Buildings to the 2017 Puebla Earthquake

Earthquake Spectra ◽

10.1193/061218eqs144m ◽

2019 ◽

Vol 35 (4) ◽

pp. 1763-1793 ◽

Cited By ~ 1

Author(s):

Carlos A. Arteta ◽

Julian Carrillo ◽

Jorge Archbold ◽

Daniel Gaspar ◽

Cesar Pajaro ◽

...

Keyword(s):

Reinforced Concrete ◽

The United States ◽

Rc Buildings ◽

Reinforced Concrete Frame ◽

Infill Walls ◽

Concrete Frame ◽

Soft Story ◽

Masonry Infills ◽

Rc Frames ◽

Ductility Capacity

The response of mid-rise reinforced concrete (RC) buildings in Mexico City after the 2017 Puebla Earthquake is assessed through combined field and computational investigation. The Mw 7.1 earthquake damaged more than 500 buildings where most of them are classified as mid-rise RC frames with infill walls. A multinational team from Colombia, Mexico, and the United States was rapidly deployed within a week of the occurrence of the event to investigate the structural and nonstructural damage levels of over 60 RC buildings with 2–12 stories. The results of the study confirmed that older mid-rise structures with limited ductility capacity may have been shaken past their capacity. To elucidate the widespread damage in mid-rise RC framed structures, the post-earthquake reconnaissance effort is complemented with inelastic modeling and simulation of several representative RC framing systems with and without masonry infill walls. It was confirmed that the addition of non-isolated masonry infills significantly impacts the ductility capacity and increases the potential for a soft-story mechanism formation in RC frames originally analyzed and designed to be bare systems.

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Numerical Study of the In-Plane Seismic Response of RC Infilled Frames

Construction Materials ◽

10.3390/constrmater1010006 ◽

2021 ◽

Vol 1 (1) ◽

pp. 82-94

Author(s):

Matteo Bagnoli ◽

Ernesto Grande ◽

Gabriele Milani

Keyword(s):

Seismic Vulnerability ◽

Numerical Study ◽

Pushover Analysis ◽

Experimental Tests ◽

Economic Losses ◽

Rc Buildings ◽

Infilled Frames ◽

Masonry Infills ◽

Reliable Model ◽

The Common

Reinforced Concrete (RC) buildings with masonry infills are a very common structural typology worldwide for civil, strategic, or productive use. Damage to infills may cause danger for human lives and strongly affects economic losses, as shown during past earthquakes. In the current literature, different approaches are available for modeling the in-plane response of infilled frames and different constitutive laws generally calibrated on experimental tests. On the contrary, few and recent studies proposed formulas that account for the main properties of infills influencing their in-plane behavior to lateral forces. This paper presents a study finalized to derive a reliable model that is able to predict the monotonic and cyclic response of RC infilled masonry frames. To this end, after a critical analysis of the available literature, the authors combine among them two models, one for the monotonic response and the other for the cyclic one, by showing their reliability with reference to different experimental cases. Then, at the end of the paper, the derived models are employed to assess the seismic vulnerability of infills throughout a proposed procedure based on the common pushover analysis approach.

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Seismic Loss Estimation in Pre-1970 Residential RC Buildings: The Role of Infills and Services in Low–Mid-Rise Case Studies

Frontiers in Built Environment ◽

10.3389/fbuil.2020.589230 ◽

2020 ◽

Vol 6 ◽

Author(s):

Carlo Del Gaudio ◽

Maria Teresa De Risi ◽

Santa Anna Scala ◽

Gerardo Mario Verderame

Keyword(s):

Case Studies ◽

Pushover Analysis ◽

Economic Loss ◽

Loss Estimation ◽

Lessons Learned ◽

Rc Buildings ◽

Loss Assessment ◽

Ground Acceleration ◽

Masonry Infills

The lessons learned after recent earthquakes have highlighted the key role played by infills and services in damage and loss of Reinforced Concrete (RC) buildings. Their influence in seismic performance and loss estimation of selected RC building case studies is thoroughly analyzed here. The case study selection aims to be representative of existing buildings built in Italy before 1970, and covers a different number of stories and design typologies. The seismic responses of the case-study buildings are numerically analyzed by means of non-linear static pushover analysis (PO) considering a lumped plasticity approach with a quadri-linear flexural response for beam/column elements (properly calibrated for RC elements reinforced with plain bars) and a tri-linear compressive-only axial response with diagonal concentric struts for infill panels (empirically derived from experimental data on hollow clay masonry walls). Economic loss estimation is carried out via a component-based methodology that relies on the main repairing activities and resultant costs required for the refurbishment of infills and services for different damage levels. Accordingly, a damage analysis is performed herein, given the intensity measure, based on a comparison between Interstory drift demand from PO analysis and drift-based fragility functions specific for masonry infills. Loss curves, relating the total building repair cost to peak ground acceleration (PGA), are presented and compared for the analyzed case study buildings to show their trends and quantify the incidence of infills and services with respect to the reconstruction cost. A comparison between these outcomes and those recently found in the literature emphasizes the robustness of the considered approach and the reliability of the hypotheses about damage and loss assessment.

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Comparison of Interstorey Drift in General RC Buildings in Pounding and No Pounding Case

Technical Journal ◽

10.3126/tj.v2i1.32828 ◽

2020 ◽

Vol 2 (1) ◽

pp. 40-47

Author(s):

Anand Dev Bhatt

Keyword(s):

Seismic Analysis ◽

Linear Time ◽

Time History ◽

Case Analysis ◽

Rc Buildings ◽

Adjacent Buildings ◽

Sufficient Distance ◽

Earthquake Load ◽

Interstorey Drift ◽

Lower Height

Inter-storey drift is an important parameter of structural behavior in seismic analysis of buildings. Pounding effect in building simply means collision between adjacent buildings due to earthquake load caused by out of phase vibration of adjacent buildings. There is variation in inter-storey drift of adjacent buildings during pounding case and no pounding case. The main objective of this research was to compare the inter-storey drift of general adjacent RC buildings in pounding and no pounding case. For this study two adjacent RC buildings having same number of stories have been considered. For pounding case analysis there is no gap in between adjacent buildings and for no pounding case analysis there is sufficient distance between adjacent buildings. The model consists of adjacent buildings having 4 and 4 stories but unequal storey height. Both the buildings have same material & sectional properties. Fast non-linear time history analysis was performed by using El-centro earthquake data as ground motion. Adjacent buildings having different overall height were modelled in SAP 2000 v 15 using gap element for pounding case. Finally, analysis was done and inter-storey drift was compared. It was found that in higher building inter-storey drift is greater in no pounding case than in pounding case but in adjacent lower height building the result was reversed. Additionally, it was found that in general residential RC buildings maximum inter-storey drift occurs in 2nd floor.

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Influence of floor system on seismic behavior of RC buildings to forward directivity and fling-step in the near-fault region

Structures ◽

10.1016/j.istruc.2021.01.052 ◽

2021 ◽

Vol 30 ◽

pp. 803-817

Author(s):

Sayed Mahmoud ◽

Ali Alqarni ◽

Joseph Saliba ◽

Amal H. Ibrahim ◽

Magdy genidy ◽

...

Keyword(s):

Seismic Behavior ◽

Rc Buildings ◽

Near Fault ◽

Forward Directivity ◽

Fling Step ◽

Floor System ◽

Fault Region

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Innovative seismic isolation of masonry infills using cellular material at the interface with the surrounding RC frame

Journal of Building Engineering ◽

10.1016/j.jobe.2021.102736 ◽

2021 ◽

pp. 102736

Author(s):

Zeeshan Umar ◽

Syed Azmat Ali Shah ◽

Tayyaba Bibi ◽

Khan Shahzada ◽

Asfandyar Ahmad

Keyword(s):

Seismic Isolation ◽

Cellular Material ◽

Rc Frame ◽

Masonry Infills

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Investigation of Diagonal Strut Actions in Masonry-Infilled Reinforced Concrete Frames

International Journal of Concrete Structures and Materials ◽

10.1186/s40069-020-00440-x ◽

2021 ◽

Vol 15 (1) ◽

Author(s):

Seung-Jae Lee ◽

Tae-Sung Eom ◽

Eunjong Yu

Keyword(s):

Reinforced Concrete ◽

Failure Mode ◽

Yield Criterion ◽

Friction Angle ◽

Concrete Frames ◽

Element Analysis ◽

Reinforced Concrete Frames ◽

Infilled Frames ◽

Masonry Infills ◽

Push Down

AbstractThis study analytically investigated the behavior of reinforced concrete frames with masonry infills. For the analysis, VecTor2, a nonlinear finite element analysis program that implements the Modified Compression Field Theory and Disturbed Stress Field Model, was used. To account for the slip behavior at the mortar joints in the masonry element, the hyperbolic Mohr–Coulomb yield criterion, defined as a function of cohesion and friction angle, was used. The analysis results showed that the lateral resistance and failure mode of the infilled frames were significantly affected by the thickness of the masonry infill, cohesion on the mortar joint–brick interface, and poor mortar filling (or gap) on the masonry boundary under the beam. Diagonal strut actions developed along two or three load paths on the mortar infill, including the backstay actions near the tension column and push-down actions near the compression columns. Such backstay and push-down actions increased the axial and shear forces of columns, and ultimately affect the strength, ductility, and failure mode of the infilled frames.

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