Evaluation of the period and soft story conditions of reinforced concrete buildings with and without infill walls

2021 ◽  
Vol 7 (3) ◽  
pp. 151
Author(s):  
Başak Zengin
Keyword(s):  
Reinforced Concrete ◽  
Shear Walls ◽  
Structural System ◽  
Infill Wall ◽  
Infill Walls ◽  
Earthquake Energy ◽  
Ground Floor ◽  
Earthquake Loads ◽  
Soft Storey ◽  
Soft Story

Since the ground floor of most of the buildings in our country is designed as a shop or ground floor (in the buildings created as a workplace), there is very little infill wall ratio on the ground floors due to architectural and functional reasons, and some of them do not even exist at all. However, infill walls significantly increase the horizontal rigidity and strength of the structure, thus causing a decrease in the period value that determines the earthquake loads that will affect the structure. However, the infill wall meets the first destructive forces of the earthquake, and during this time, it cracks and absorbs some of the earthquake energy. The structural system elements of the building (columns and shear walls) start to meet the earthquake forces only when the infill walls are damaged and fail. In this direction, the aim of this study is to investigate to what extent the amount of infill wall on the ground floor affects the period of the building, and whether there are soft storey irregularities in the building according to the change in the amount of infill wall on the ground floor. In this study, while there are infill walls on all floors and all axes of buildings of various heights (3, 6, 9 and 11 floors), the amount of infill walls in the x and y directions on the ground floors is reduced to a certain extent, and many models are created until the ground floor is completely without infill walls. All these models created were analyzed with the support of the SAP2000 program, and the period values were determined and examined according to the soft storey problems and compared with the case of the entire building with and without infill walls. In addition, it was examined whether the period formulas determined as a result of the studies and taking into account the infill wall give realistic results for the situation examined in this study.

THE EFFECT OF PLACEMENT OF L-TYPE SHEAR WALLS IN RC STRUCTURES ON STRUCTURAL BEHAVIOR

2021 ◽  
Vol 0 (15) ◽  
pp. 0-0
Author(s):  
Muhammet Zeki ÖZYURT
Keyword(s):  
Reinforced Concrete ◽  
Natural Vibration ◽  
Shear Walls ◽  
Shear Wall ◽  
Structural Behavior ◽  
Structural System ◽  
Reinforced Concrete Structure ◽  
Vibration Period ◽  
Peak Displacement ◽  
Ground Floor

Aim: In this study; In this study, it was investigated how the symmetrical and different positions of the L-type shear walls on the floor plan affect the structural behavior in the reinforced concrete residential and office buildings with a symmetrical structural system. Method: In the study, three different carrier system types were created for a symmetrical reinforced concrete structure with 5 floors (ground floor + 4 normal floors), according to the shear wall layouts, and on a total of 12 different models (ground floor heights of 2.5 m, 3.0 m, 4.0 m and 5 m) was examined. Results: It was determined that as the ground floor height increased, the natural vibration period, soft floor irregularity coefficient and peak displacement value also increased in all models examined in the study. It has been observed that the natural vibration period is greater when the shear walls are located at the corners of the outer axles than if they are located in the middle of the outer axles and in the inner axles. It has been observed that in all cases of ground floor height, the number of soft floor irregularities in the corner shear wall layout model on the outer axes is approximately 0.2% higher than in the Type 2 situation. Conclusion: In this study, for the 5-storey reinforced concrete structures used for workplace and residential purposes, whose structural system is determined symmetrically so that torsional irregularity does not occur, the results obtained by changing the placement of L-section shear walls in the plan, drew attention to the fact that the position of the shear wall affects the structural behavior. For buildings with a ground floor height less than or equal to the normal floors, the most appropriate shear wall placement is when the shear walls are on the outer axes and in the corner. For buildings with a ground floor height higher than normal floors, the most appropriate shear wall placement takes place on the inner axes of the building.

SEISMIC BEHAVIOR OF UNREINFORCED CONCRETE MASONRY INFILL WALLS

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Ziad Azzi ◽  
Caesar Abi Shdid
Keyword(s):  
Reinforced Concrete ◽  
Ground Motion ◽  
Element Model ◽  
Reinforced Concrete Frame ◽  
Infill Wall ◽  
Infill Walls ◽  
Existing Building ◽  
Masonry Infill ◽  
Masonry Infill Walls ◽  
Out Of Plane

The majority of new and existing building inventories in the Middle East consist of reinforced concrete skeletal structures with outer shells composed of unreinforced masonry infill walls. In the absence of any mandatory seismic design requirements, these buildings will sustain catastrophic damage when exposed to high seismic activity. Investigating the behavior of such infill walls when exposed to ground motion is therefore an important topic. Experimental tests using shake table out-of-plane ground motion of the 1940 El Centro earthquake displacement are conducted on 3:10 scaled specimens of a single story reinforced concrete frame with a masonry infill wall in between. The test specimens are constructed with the same materials and construction practices commonly used in the region. Displacements and strains are compared with a finite element model of the frame. Moreover, the observed overall behavior of the infill is compared to that of the computer model. The recorded strains in the mortar joints exceeded cracking limits, whereas the overall stability of the wall in out-of-plane bending was not compromised. Recommendations on the use of these structural elements are formulated.

scholarly journals Determination of Period of RC Buildings by the Ambient Vibration Method

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Mehmet Inel ◽  
Hayri Baytan Ozmen ◽  
Bayram Tanik Cayci
Keyword(s):  
Natural Vibration ◽  
Dynamic Properties ◽  
Shear Walls ◽  
Vibration Signal ◽  
Analytical Models ◽  
Ambient Vibration ◽  
Seismic Behaviour ◽  
Infill Wall ◽  
Infill Walls ◽  
Vibration Period

Determining the dynamic properties of structures is important for understanding their seismic behaviour. Ambient vibration signal measurement is one of the approaches used to determine the period of structures. Advantages of this method include the possibility of taking real-time records and presenting nondestructive and rapid solutions. In this study, natural vibration periods are calculated by taking ambient vibration signal records from 40 buildings. The height of the building, infill wall effect, presence of seismic retrofit, and presence of damage are taken into consideration, and their effects on natural vibration periods are investigated. Moreover, the results are compared with the analytical methods to reveal the differences. A significant correlation between the period and height of the building is observed. It is seen that the natural vibration periods of the buildings decrease by 7% to 30% (15% on average) due to infill wall contribution. However, the efficiency of infill walls decreases as the building height increases. Another significant result is that adding shear walls substantially decreases the vibration period values by 23% to 33% with respect to the shear wall ratio. When the analytical estimates and measured building period results are compared, it is seen that analytical models have closer period estimates before infill walls are implemented. The limited data in scope of the study suggest that significant differences may present in the analytical and measured periods of the buildings due to infill wall contributions.

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.

Seismic response analyses and performance assessment of masonry-infilled reinforced concrete frame buildings in Bhutan without and with soft storey

2016 ◽  
Vol 20 (5) ◽  
pp. 822-839
Author(s):  
Kinzang Thinley ◽  
Hong Hao
Keyword(s):  
Reinforced Concrete ◽  
Return Period ◽  
Ground Motions ◽  
Reinforced Concrete Frame ◽  
Infill Wall ◽  
Soft Storey ◽  
Concrete Frame ◽  
Seismic Design Code ◽  
Frame Buildings ◽  
High Seismicity

Bhutan locates in a high seismicity region but has no seismic design code of its own. Recent devastating earthquake in Nepal, which is located in the same region as Bhutan and with similar construction types, raises the concern on the seismic safety of building structures in Bhutan. This study is aimed at assessing the performance of masonry-infilled and soft storey reinforced concrete frame buildings in Bhutan under the 475- and 2475-year return period ground motions predicted from the Probabilistic Seismic Hazard Analysis. A nonlinear strut model is used to model the infill wall, and the influence of openings and soil–structure interaction are considered in the analyses. The result suggests that the masonry-infilled reinforced concrete frame buildings in Bhutan could suffer repairable and irreparable damages under the 475-year return period ground motions and severe damages and even collapse under the 2475-year return period ground motion. The buildings with the soft storey are found to be more vulnerable than the normal masonry-infilled reinforced concrete buildings. The design recommendation of Indian Seismic Code improves the performance of soft storey buildings but cannot fully negate the soft storey effect. This study is the first such effort in assessing the performance of general building stocks in the high seismicity Bhutan. The results can guide the seismic strengthening options and can be used for further loss predictions for seismic preparedness of the country.

scholarly journals Seismic Performance Evaluation of Multi-Storey Building Having Soft Storey With Different Location of Shear Walls

2020 ◽  
Vol 9 (11) ◽  
pp. 50-55
Keyword(s):  
Shear Walls ◽  
Base Shear ◽  
Soft Storey ◽  
Seismic Performance Evaluation ◽  
Soft Story ◽  
Time Period ◽  
Multistory Building ◽  
Story Drift ◽  
Seismic Behaviors ◽  
Storey Building

Present scenario growth of Multistory building is incredibly high attributable to fast growth everywhere around the globe. Open first story is usually provided for congested parking space, reception lobbies, party areas or any purpose in multistory building. However just in case of multistory building with soft story provides reduced performance. There are numerous aspects that effects on the behavior of multistory building like irregular plan within the structure. In the present work, study of various locations of weak stories is being considered for the analysis. To study of various locations on the seismic behavior of multistory building, linear static analysis (ESA) and linear dynamic analysis (RSA) in ETABs 2016 version is applied. Some seismic constraints like time period, story shear, story displacement, story drift and base shear are tried. The seismic behaviors of multistorey building with soft stories are administered.

scholarly journals Seismic Analysis of 3D Framed Building

2021 ◽  
pp. 404-410
Author(s):  
S. Venkatesh ◽  
Ms. T. Savithra
Keyword(s):  
Seismic Analysis ◽  
Shear Walls ◽  
Infill Walls ◽  
Efficient System ◽  
Framed Structures ◽  
Masonry Infill ◽  
Soft Storey ◽  
Masonry Infill Walls ◽  
Frame Building ◽  
Rigid Frames

Generally RC framed structures are designed without regards to structural action of masonry infill walls present. Masonry infill walls are widely used as partitions. These buildings are generally designed as framed structures without regard to structural action of masonry infill walls. They are considered as non- structural elements. RC frame building with open first storey is known as soft storey, which performs poorly during strong earthquake shaking. Past earthquakes are evident that collapses due to soft storeys are most often in RC buildings. In the soft storey, columns are severely stressed and unable to provide adequate shear resistance during the earthquake. Hence a combination of two structural system components i.e. Rigid frames and RC shear walls or Rigid frames and Bracings leads to a highly efficient system in which shear wall and bracings resist the majority of the lateral loads and the frame supports majority of the gravity loads.

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.

Comportement sismique d'un système formé de murs couplés tronqués et d'un cadre

2001 ◽  
Vol 28 (4) ◽  
pp. 752-758
Author(s):  
O Chaallal ◽  
P Malenfant ◽  
M -J Nollet
Keyword(s):  
Reinforced Concrete ◽  
Seismic Behavior ◽  
Shear Walls ◽  
Ductility Demand ◽  
Soft Story ◽  
Plastic Mechanism ◽  
Wide Range ◽  
Frame System ◽  
Seismic Records ◽  
Frame Systems

This paper presents results of a numerical investigation on the nonlinear seismic behavior of a reinforced concrete system made of truncated coupled shear walls (CSWs) and a frame. The objective of the study is twofold: (a) examine the seismic behavior of CSW–frame systems with setbacks and (b) verify the adequacy of the National Building Code (NBC) as far as the design of such systems. The study considers two types of CSWs, coupled and partially coupled, two Canadian seismic zones, 4 and 6, six different levels of setbacks, and 10 historic seismic records encompassing a wide range of frequency content. Results of the study show that the CSW–frame system with no setback offers a satisfactory seismic behavior with regards to the sequence of plastification and the ductility demand. For the truncated systems, the NBC recommendations that the static method is not adequate is justified. Also, in the presence of setbacks, the columns show a higher degree of plastification with a possibility of formation of plastic mechanism (soft story). The ductility demand is also higher and can exceed the accepted practical limit in certain cases.Key words: coupled shear walls, frame, reinforced concrete, setback, seismic behavior, code.

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.

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