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 Effects of Single and Multi Openings in Brick Infills on the Seismic Response of Infilled RC Frames

2018 ◽  
Vol 215 ◽  
pp. 01036
Author(s):  
Maidiawati ◽  
Jafril Tanjung ◽  
Hamdeni Medriosa ◽  
Yulia Hayati
Keyword(s):  
Seismic Response ◽  
Dissipated Energy ◽  
Rc Frame ◽  
Infilled Frames ◽  
Masonry Infill ◽  
Infilled Frame ◽  
Rc Frames ◽  
Central Opening ◽  
Lateral Strength ◽  
Infilled Rc Frames

Many researchers have performed a lot of studies of the seismic behavior reinforced concrete (RC) frame with masonry infill. They found that masonry infill affects the lateral strength, stiffness and ductility performance of the RC frame structures. However, when openings appeared in the panel infill for door and windows, the responses of the overall structure are entirely changed. The primary purpose of this study is to experimentally investigate the behavior of brick infilled RC frames possessing single opening and two openings. Four specimens of 1/4-scale single bay RC frames with brick infills were made that were one bare frame, one frame with full infill and two frames with infills having a central opening and two openings with the opening ratio of 25%. The specimens were tested under lateral reversed cyclic loads. Consequently, different responses of failure mechanism, lateral strength, stiffness and energy dissipated were observed among the specimens. The brick full infill failed in shear with propagation cracks in central part of the panel, but in the case of the infills with single and two openings, the cracks were dominated at the corners of the openings. The in-plane strength, stiffness and dissipated energy of infilled frames decreased when openings appeared in the panel. However, the seismic performance of brick infilled frame with the opening of 25% of panel area is better than those of bare frame. The brick infilled frames with a central opening and two openings are similar in lateral strength and dissipated energy. It seems that area and position of the openings control the seismic response to the overall infilled frame structure of the openings

Seismic Performance Improvement of 3D Reinforced Concrete Frames with Different Strengthening Applications

2015 ◽  
Vol 789-790 ◽  
pp. 1140-1144
Author(s):  
Fatih Bahadir ◽  
Fatih Süleyman Balik
Keyword(s):  
Reinforced Concrete ◽  
Reference Specimen ◽  
Brick Wall ◽  
Concrete Frames ◽  
Infill Wall ◽  
Reinforced Concrete Frames ◽  
Window Opening ◽  
Lateral Strength ◽  
External Frame ◽  
Rc Shear Wall

This study used test frames were purposely detailed and constructed with observed deficiencies in investigated dormitory buildings of Turkey. In this study, four reinforced concrete frames were produced two storeys, one bay and 3D in 1/6 geometric scale was tested. Since the studied frame was the external frame of the structure, brick infill wall with a window opening was also included. The first specimen was the reference specimen and contained no strengthening and no brick wall. The second specimen was contained brick wall. The third specimen was strengthened with internal steel panel. Finally fourth specimen’s was strengthened with infilled RC shear wall. The test specimens were subjected to reversed cyclic quasi-static lateral loading. Strength of the test specimens were measured and compared. Test results indicated that the strengthened specimens displayed significantly higher lateral strength than the reference specimen considerably.

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.

Ductility Reduction Factors for Masonry-Infilled Reinforced Concrete Frames

2015 ◽  
Vol 31 (1) ◽  
pp. 339-365 ◽  
Author(s):  
Manish Kumar ◽  
Durgesh C. Rai ◽  
Sudhir K. Jain
Keyword(s):  
Reinforced Concrete ◽  
Traditional Approach ◽  
Statistical Tests ◽  
Experimental Studies ◽  
Reduction Factor ◽  
Model Parameters ◽  
Deformation Model ◽  
Concrete Frames ◽  
Ductility Demand ◽  
Rc Frames

Masonry-infilled reinforced concrete (RC) frames are popular structural systems; however, there is much uncertainty in their response under seismic loads. Using the data from past experimental studies, a simple force-deformation model with three control points was developed. The effect of the model parameters on the ductility reduction factor (DRF) and ductility demand (DD) was examined. Statistical tests indicated that the ratio of residual strength to peak strength was the most significant parameter. The traditional approach to determining DRF ordinates through iteration for an assumed value of ductility may result in inappropriate DRF values because of the nonmonotonic relationship between DRF and DD. Constant ductility charts were developed to appropriately account for nonmonotonicity. It was found that the allowable DRF may be much higher if relatively weaker infill compared to the strength of the frame is used, which underscores the need for modifying code provisions because they allow relatively strong infill.

scholarly journals Cyclic Responses of Two-Side-Connected Precast-Reinforced Concrete Infill Panels with Different Slit Types

Buildings ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 16
Author(s):  
Guohua Sun ◽  
Fei Li ◽  
Qiyou Zhou
Keyword(s):  
Reinforced Concrete ◽  
Energy Dissipation ◽  
Failure Mode ◽  
Damping Ratio ◽  
Concrete Strength ◽  
Plastic Hinge ◽  
Cyclic Behavior ◽  
Lateral Stiffness ◽  
Lateral Strength ◽  
Energy Dissipation Capacity

This study aimed to study the cyclic behavior of two-side-connected precast-reinforced concrete infill panel (RCIP). A total of four RCIP specimens with different slit types and height-to-span ratios modeled at a one-third scale were tested subjected to cyclic lateral loads. The failure mode, hysteretic behavior, lateral strength, stiffness degradation, ductility, and energy dissipation capacity of each RCIP specimen were determined and analyzed. The specimens experienced a similar damage process, which involved concrete cracking, steel rebar yielding, concrete crushing, and plastic hinge formation. All the specimens showed pinched hysteretic curves, resulting in a small energy dissipation capacity and a maximum equivalent viscous damping ratio lower than 0.2. The specimens with penetrated slits experienced ductile failure, in which flexural hinges developed at both slit wall ends. The application of penetrated slits decreased the initial stiffness and lateral load-bearing capacity of the RC panel but increased the deformation capacity, the average ultimate drift ratios ranged from 1.41% to 1.99%, and the lowest average ductility ratio reached 2.48. The specimens with high-strength concrete resulted in a small slip no more than 1 mm between the RC panel and steel beam, and the channel shear connectors ensured that the RC infill panel developed a reliable assembly with the surrounding steel components. However, specimens with concealed vertical slits (CVSs) and concealed hollow slits (CHSs) achieved significantly higher lateral stiffness and lateral strength values. Generally, the specimens exhibited two-stage mechanical features. The concrete in the CVSs and CHSs was crushed, and flexural plastic hinges developed at both ends of the slit walls during the second stage. With increasing concrete strength, the initial lateral stiffness and lateral strength values of the RCIP specimens increased. With an increasing height-to-span ratio, the lateral stiffness and strength of the RC panels with slits decreased, but the failure mode remained unchanged.

scholarly journals Design Proposal for Masonry Infill Walls Subject to Seismic Actions

2022 ◽  
Vol 12 (1) ◽  
pp. 503
Author(s):  
João Leite ◽  
Paulo B. Lourenço ◽  
Nuno Mendes
Keyword(s):  
National Laboratory ◽  
Reduction Factor ◽  
Sufficient Information ◽  
Design Standards ◽  
Infill Walls ◽  
Infilled Frames ◽  
Masonry Infill ◽  
Out Of Plane ◽  
Structural Engineer ◽  
Demand And Capacity

Several factors influence the behaviour of masonry infilled frames, which have been the subject of previous research with moderate success. The new generation of European design standards imposes the need to prevent the brittle collapse of infills and makes the structural engineer accountable for this requirement, yet it fails to provide sufficient information for masonry infill design. The present study aimed to compare experimental results with the provisions of the standard for the computation of the demand and capacity of infilled frames. Three reinforced concrete buildings with different infill solutions were constructed at a 1:1.5 scale. The infill walls were tested until collapse, or severe damage, using the shake table of the National Laboratory for Civil Engineering, Portugal, and their response was measured using accelerometers attached to the walls. The European normative standard provides results close to the experimental ones as far as demand and capacity are concerned. Based on the experiments, two design proposals for infill walls are presented here, one for the definition of the natural frequency of the infills, and another for a reduction factor to account for the presence of openings in the out-of-plane capacity of infills.

Seismic Performance of Nonductile Reinforced Concrete Frames with Masonry Infill Walls—II: Collapse Assessment

2016 ◽  
Vol 32 (2) ◽  
pp. 819-842 ◽  
Author(s):  
Siamak Sattar ◽  
Abbie B. Liel
Keyword(s):  
Reinforced Concrete ◽  
Los Angeles ◽  
Nonlinear Models ◽  
Companion Paper ◽  
Concrete Frames ◽  
Infill Walls ◽  
Infilled Frames ◽  
Beam Columns ◽  
Collapse Behavior ◽  
Rc Frame Buildings

This paper quantifies the collapse performance of a set of masonry-infilled reinforced concrete (RC) frame buildings that are representative of 1920s-era construction in Los Angeles, California. These buildings have solid clay-brick infill walls and vary in height (2–8 stories), wall configuration (bare, partially, and fully infilled frames), and wall thickness (1–3 wythes). The buildings’ collapse behavior is assessed through dynamic analysis of nonlinear models. These models represent the walls by diagonal struts whose properties are developed from finite-element (FE) analyses, as described in the companion paper, and represent beam-columns with lumped-plasticity models. The results indicate that the presence of infill walls can increase the risk of collapse. The most collapse prone of the buildings considered are those with strong, heavy infill walls, which induce large force demands in the frame elements. The partially infilled frames, which have a soft and weak first story, also perform poorly.

Progressive Collapse Analysis of Reinforced Concrete Frames with Unreinforced Masonry Infill Walls considering In-Plane/Out-of-Plane Interaction

2015 ◽  
Vol 31 (2) ◽  
pp. 921-943 ◽  
Author(s):  
Khalid M. Mosalam ◽  
Selim Günay
Keyword(s):  
Reinforced Concrete ◽  
Shear Failure ◽  
Progressive Collapse ◽  
Unreinforced Masonry ◽  
Concrete Frames ◽  
Infill Wall ◽  
Infill Walls ◽  
Rc Frames ◽  
Out Of Plane ◽  
Plane Interaction

Reinforced concrete (RC) frames with unreinforced masonry (URM) infill walls are commonly used in seismic regions around the world. It is recognized that many buildings of this type perform poorly during earthquakes. Therefore, proper modeling of the infill walls and their effect on RC frames is essential to evaluate the seismic performance of such buildings and to select adequate retrofit methods. Using damage observations of RC buildings with URM infill walls from recent earthquakes, this paper presents a new approach to consider in-plane/out-of-plane interaction of URM infill walls in progressive collapse simulations. In addition, the infill wall effect to induce shear failure of columns is simulated with a nonlinear shear spring modeling approach. The research endeavor is accompanied by implementation of the developed modeling aspects in the publicly available open-source computational platform OpenSees for immediate access by structural engineers and researchers.

scholarly journals Examination of Anchorage of Mesh Wire on Seismic Response of Infilled Walls in RC Frames

2021 ◽  
Author(s):  
Ali Al-Maliki ◽  
◽  
Mohammed Sahib Mohammed ◽  
Maha Al-Soudani ◽  
Haifaa Nasser Husein ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Lateral Displacement ◽  
Lateral Load ◽  
Structural Behavior ◽  
Concrete Frames ◽  
Infill Wall ◽  
Infill Walls ◽  
Positive Effects ◽  
Rc Frames ◽  
Different Diameters

The infill walls may lose their positive effects during the first stages of earthquakes, either by leaving their plane or through breakage. That is why it is common to strengthen these walls before design earthquakes or to repair and strengthen them after suffering slight or moderate damage due to the occurrence of an earthquake. In this study, the effect of adding and strengthening these walls on the structural behavior of reinforced concrete structures was investigated. For this purpose, the infill walls were strengthened with a single mesh of reinforcement and covered with plaster. Five one-story, single bay and ½ scaled reinforced concrete frames were cast, one was built without infill, the second with a bare infill wall, and the other three with strengthened infill walls with anchorage of different diameters. All these specimens were tested under cyclic loading type reverse. The tests resulted in important relationships and curves, including the lateral load-lateral displacement, envelope curve-lateral load and lateral displacement, as well as stiffness- lateral displacement and others. Through these results, the effect of adding infill walls and the strengthening procedure of these walls on the structural behavior of the structures was discussed.

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