scholarly journals Seismic Evaluation and Retrofit of Reinforced Concrete Buildings with Masonry Infills Based on Material Strain Limit Approach

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Mangeshkumar R. Shendkar ◽  
Denise-Penelope N. Kontoni ◽  
Sasankasekhar Mandal ◽  
Pabitra Ranjan Maiti ◽  
Omid Tavasoli
Keyword(s):  
Reinforced Concrete ◽  
Reduction Factor ◽  
Seismic Evaluation ◽  
Infill Walls ◽  
Rc Structures ◽  
Infilled Frame ◽  
Response Reduction Factor ◽  
Masonry Infills ◽  
Strain Limit ◽  
Open Ground

The seismic evaluation and retrofit of reinforced concrete (RC) structures considering masonry infills is the correct methodology because the infill walls are an essential part of RC structures and increase the stiffness and strength of structures in seismically active areas. A three-dimensional four-storey building with masonry infills has been analyzed with nonlinear static adaptive pushover analysis by using the SeismoStruct software. Two models have been considered in this study: the first model is a full RC-infilled frame and the second model is an open ground storey RC-infilled frame. The infill walls have been modeled as a double strut nonlinear cyclic model. In this study, the “material strain limit approach” is first time used for the seismic evaluation of RC buildings with masonry infills. This method is based on the threshold strain limit of concrete and steel to identify the actual damage scenarios of the structural members of RC structures. The two models of the four-storey RC building have been retrofitted with local and global strengthening techniques (RC-jacketing method and incorporation of infills) as per the requirements of the structure to evaluate their effect on the response reduction factor (R) because the R-factor is an important design tool that shows the level of inelasticity in a structure. A significant increase in the response reduction factor (R) and structural plan density (SPD) has been observed in the case of the open ground storey RC-infilled frame after the retrofit. Thus, this paper aims to present a most effective way for the seismic evaluation and retrofit of any reinforced concrete structure through the material strain limit approach.

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

2019 ◽  
Vol 35 (4) ◽  
pp. 1763-1793 ◽  
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.

scholarly journals Numerical analysis of reinforced concrete frame buildings with decoupled infill walls

2020 ◽  
Vol 63 (4) ◽  
pp. 13-48
Author(s):  
Marko Marinković ◽  
Santiago Calvinisti ◽  
Christoph Butenweg
Keyword(s):  
Reinforced Concrete ◽  
Dynamic Characteristics ◽  
Numerical Models ◽  
Rc Frame ◽  
Reinforced Concrete Frame ◽  
Infill Wall ◽  
Infill Walls ◽  
Masonry Infill ◽  
Infilled Frame ◽  
Frame Buildings

Reinforced concrete (RC) buildings with masonry infill walls are widely used in many countries all over the world. Although infills are considered as non-structural elements, they significantly change dynamic characteristics of RC frame structures during earthquake excitation. Recently, significant effort was spent on studying decoupled infills, which are isolated from the surrounding frame usually by adding a gap between frame and infill. In this case, the frame deformation does not activate infill wall, thus infills are not influencing the behaviour of the frame. This paper presents the results of the investigation of the behaviour of RC frame buildings with the INODIS system that decouples masonry infills from the surrounding frame. Effect of masonry infill decoupling was investigated first on the one-bay one-storey frame. This was used as a base for parametric study on the frames with more bays and storeys, as well as on the building level. Change of stiffness and dynamic characteristics was analysed as well as response under earthquake loading. Comparison with the bare frame and traditionally infilled frame was performed. The results show that behaviour of the decoupled infilled frames is similar to the bare frame, whereas behaviour of frames with traditional infills is significantly different and demands complex numerical models. This means that if adequate decoupling is applied, design of infilled frame buildings can be significantly simplified.

CASE STUDY OF SEISMIC EVALUATION AND STRENGTHENING OF EXISTING LOW-RISE REINFORCED CONCRETE BUILDING

2018 ◽  
Vol 5 (1) ◽  
Author(s):  
Amthal Hakim ◽  
Adnan Masri
Keyword(s):  
Reinforced Concrete ◽  
Shear Walls ◽  
Evaluation Process ◽  
Seismic Evaluation ◽  
Rc Structures ◽  
The Status ◽  
Earthquake Design ◽  
Bracing System ◽  
New Buildings

All new buildings nowadays have to be designed and executed to overcome any imposed type of loading (lateral/vertical). On a universal scale, the stock of buildings built before 1980’s is believed to be many times more than the number of newer buildings in most urban cities. In Beirut, as an example, a large proportion of Reinforced Concrete (RC) structures were constructed in the absence of mandatory earthquake design requirements, and unquestionably recognized as the type of construction most vulnerable to earthquakes. The performed research focused on how to evaluate the status of old building and how to design and execute the convenient seismic strengthening schemes. A case study has been selected to implement the evaluation process and design proposals. Conventional seismic upgrading technique has been assessed like the addition of shear walls in addition to more innovative approach which is the installation of steel bracing system. The strengthening schemes proposed aimed to create an ideal harmonization of the technical, economic and social aspects of the issue in hand. Analysis of the three structural systems (existing, modified with shear walls and with bracing systems) has been performed using the ETABS software including static equivalent, dynamic and pushover analyses. The research sorted out with a comparison between the systems based on different structural criteria followed by general recommendations and suggestions.

scholarly journals Lateral Stiffness of Masonry Infilled Reinforced Concrete (RC) Frames with Central Opening

2008 ◽  
Vol 24 (3) ◽  
pp. 701-723 ◽  
Author(s):  
Goutam Mondal ◽  
Sudhir K. Jain
Keyword(s):  
Reinforced Concrete ◽  
Reduction Factor ◽  
Lateral Stiffness ◽  
Effective Width ◽  
Infill Walls ◽  
Infilled Frames ◽  
Rc Frames ◽  
Window Opening ◽  
Central Opening ◽  
Lateral Strength

Window and door openings are inevitable parts of infill walls for functional reasons. Currently, publications like FEMA-273 and ATC-40 contain provisions for the calculation of stiffness of solid infilled frames mainly by modeling infill as a “diagonal strut.” However, such provisions are not provided for infilled frames with openings. The present study proposes a reduction factor for effective width of diagonal strut over that of the solid reinforced concrete (RC) infilled frame to calculate its initial lateral stiffness when a central window opening is present. The study is based on initial lateral stiffness which is taken at 10% of the lateral strength of the infilled frames.

scholarly journals Evaluation of Response Reduction Factor of Existing Masonry Infilled RC-Buildings in Pokhara

2020 ◽  
Vol 1 (1) ◽  
pp. 41-51
Author(s):  
Tekkan Pandit ◽  
Hemchandra Chaulagain
Keyword(s):  
Pushover Analysis ◽  
Structural Response ◽  
Reduction Factor ◽  
Base Shear ◽  
Rc Buildings ◽  
Design Standards ◽  
Natural Period ◽  
Infill Walls ◽  
Response Reduction Factor ◽  
R Value

Most of the structural designer do not consider masonry infill walls during design process due to a lack of modeling guidelines in design standards and are treated as non-structural elements. In fact, the interaction effect between bounding frames and infill masonry is a complicated issue in nonlinearity of structures. The current seismic codes indirectly incorporate the nonlinear response of structure through linear elastic approach by considering the response reduction factor ‘R’ without comprising infill. In this context, this study evaluates the response reduction factor of existing engineered designed RC frame structures that are designed based on Indian standard codes. For this, three existing RC buildings were selected and performed non-linear pushover analysis. The structural response was examined in terms of natural period, base shear, strength, stiffness, ductility and response reduction factor. The results specify that the buildings with infill walls significantly influence on ‘R’ value of structures. Additionally, study shows that the variation of ‘R’ value mainly depends on the percentage of infill inclusion.

scholarly journals Effect of stiffeners in lateral stiffness of masonry infill reinforced concrete (RC) frames

2015 ◽  
Vol 3 ◽  
pp. 7-20 ◽  
Author(s):  
Chandra Kiran Kawan
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Element Model ◽  
Reduction Factor ◽  
Lateral Stiffness ◽  
Reinforced Concrete Frame ◽  
Masonry Infill ◽  
Wooden Frame ◽  
Infilled Frame ◽  
Gap Element

Infilled frames are reinforced concrete frames with masonry infill. The provision of masonry walls as infill increases the lateral stiffness of frame. Unreinforced masonry infill effects the strength and stiffness of frame but being ignored for a long time. The main objective of this paper is to study the individual and combined effect of infill masonry wall, stiffeners and wooden frame in the lateral stiffness of infill reinforced concrete frame with central opening, with and without gap element consideration. From the analysis using SAP software, it is observed that with increase in openings, stiffness decreases but introducing stiffeners and wooden frame increases the lateral stiffness. Embedding the gap element as the boundary condition reduces the stiffness of the infilled frame. Numerical investigations are carried out by finite element modeling for analyzing the behavior of infilled frame. The single equivalent diagonal strut width was determined by obtaining the same lateral stiffness from finite element model, and also strut reduction factor for different conditions with central openings are proposed.

scholarly journals Seismic Performance of a Three-Story Reinforced Concrete Building with Masonry Infill Walls and Friction Base Support

2021 ◽  
Vol 23 (1) ◽  
pp. 35-43
Author(s):  
Pamuda Pudjisuryadi ◽  
V.S. Prayogo ◽  
S.I. Oetomo ◽  
Benjamin Lumantarna
Keyword(s):  
Reinforced Concrete ◽  
Seismic Performance ◽  
Linear Time ◽  
Time History ◽  
Masonry Wall ◽  
Infill Wall ◽  
Infill Walls ◽  
Rc Structures ◽  
Masonry Infill ◽  
Masonry Infill Walls

The stiffness of masonry infill walls is commonly neglected in design practice of Reinforced Concrete (RC) structures. In fact, the stiffness of masonry infill wall may significantly influence seismic performance and dynamic behavior of RC buildings. In this research, influence of masonry infill walls to the structural performance of a three-story RC frame is investigated. In addition, possible application of friction-based support is also studied. Full 3D non-linear time history analysis is conducted to observe behavior of the structure under two-directional ground motion. In the analysis, any failed elements are removed subsequently from the model to avoid numerical analysis problem. The result shows that the placement of masonry infill walls can significantly influence the structural behavior of RC structure. Inappropriate placement of masonry wall may lead the building undergo soft-story mechanism. It is also found that the use of friction-based support can effectively improve the seismic performance of the building.

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