A Novel Technique of Seismic Strengthening of Nonductile RC Frame using Steel Caging and Aluminum Shear Yielding Damper

2009 ◽  
Vol 25 (2) ◽  
pp. 415-437 ◽  
Author(s):  
Dipti R. Sahoo ◽  
Durgesh C. Rai
Keyword(s):  
Energy Dissipation ◽  
Lateral Load ◽  
Rc Frame ◽  
Test Protocol ◽  
Shear Yielding ◽  
Reduction In Force ◽  
Rc Frames ◽  
Lateral Strength ◽  
Lateral Displacements ◽  
Strength And Stiffness

A novel strengthening scheme for seismically-weak RC frames is proposed which utilizes external steel caging to improve flexural/shear strength of columns and aluminum shear-yielding damper ( Al-SYD) to further enhance lateral strength, stiffness and overall energy dissipation capacity of the frame. This paper describes the effectiveness of this scheme as evidenced in an experimental study on a reduced scale (1:2.5) single-story, single-bay, gravity-only designed reinforced concrete (RC) frame. The strengthened frame was simultaneously subjected to gravity loads and reversed cyclic lateral displacements as per ACI-374 loading protocol. An innovative connection scheme was designed to transfer a portion of frame lateral load to the energy dissipation device ( Al-SYD). Besides the significant increase in lateral strength and stiffness of the strengthened frame, RC frame members did not suffer any major damage during the entire test protocol. This indicates significant reduction in force demand on existing RC members because of enhanced energy dissipation through hysteretic shear yielding of aluminum panels. Moreover, the simple connection scheme proposed in this study proved very efficient in transferring the frame lateral load to strengthening elements.

scholarly journals Comparative Evaluation of Concentric Bracing Systems for Lateral Loads on Medium Rise Steel Building Structures

2020 ◽  
pp. 124-130
Author(s):  
Sisaynew Tesfaw Admassu
Keyword(s):  
Lateral Displacement ◽  
Level Structure ◽  
Lateral Load ◽  
Frame Structure ◽  
Lateral Stiffness ◽  
Building Structures ◽  
Steel Buildings ◽  
Lateral Strength ◽  
Strength And Stiffness ◽  
Bracing System

To resistance, the lateral load from wind or an earthquake is that the reason for the evolution of varied structural systems. Because, when a medium or any multi-level structure is exposed to horizontal or torsional deflections under the action of seismic burdens. Lateral stiffness is a major consideration in the design of the buildings. In addition to this, many existing steel buildings and reinforced concrete buildings for which the weak lateral stiffness is the main problem; should be retrofitted to conquer the insufficiencies to resist the lateral loading. Lateral load resisting systems are structural elements providing basic lateral strength and stiffness, without which the structure would be laterally unstable. The unstable nature of the structure is solved by the fitting arrangement of bracings systems. A bracing system is that forms an integral part of the frame. Thus, such a structure has to be analyzed before arriving at the best type or effective arrangement of bracing. Bracing is a highly effective strategy of resisting lateral forces in a frame structure. In this document, a ten-story building with incorporated bracing systems is analysed using ETABS 2016 analysis software as per Eurocode and Ethiopian Building Code Standards (EBCS). Then, the lateral displacement is evaluated under each of the bracing types.

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

scholarly journals An Experimental Study on Hybrid Noncompression CF Bracing and GF Sheet Wrapping Reinforcement Method to Restore Damaged RC Structures

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Kang Seok Lee
Keyword(s):  
Seismic Retrofitting ◽  
Strengthening Effect ◽  
Reinforcement Scheme ◽  
Rc Structures ◽  
Rc Frames ◽  
Study Results ◽  
Lateral Strength ◽  
Strength And Stiffness ◽  
Cyclic Loading Tests ◽  
Bracing System

We describe a novel technique for restoration of reinforced concrete (RC) structures that have sustained damage during an earthquake. The reinforcement scheme described here is a hybrid seismic retrofitting technique that combines noncompression X-bracing using CF with externally bonded GF sheets to strengthen RC structures that have sustained damage following an earthquake. The GF sheet is used to improve the ductility of columns, and the noncompression CF X-bracing system, which consists of CF bracing and anchors to replace the conventional steel bracing and bolt connections, is used to increase the lateral strength of the framing system. We report seismic restoration capacity, which enables reuse of the damaged RC frames via the hybrid CF X-bracing and GF sheet wrapping system. Cyclic loading tests were carried out to investigate hysteresis of the lateral load-drift relations, as well as the ductility. The GF sheet significantly improved the ductility of columns, resulting in a change in failure mode. The strengthening effect of conventional CF sheets used in columns is not sufficient with respect to lateral strength and stiffness. However, this study results in a significant increase in the strength of the structure due to the use of CF X-bracing and inhibited buckling failure of the bracing. This result can be exploited to develop guidelines for the application of the reinforcement system to restore damaged RC structures.

Experimental Study on Lateral Strength Evaluation of Unreinforced Masonry-Infilled RC Frame

2016 ◽  
Vol 32 (3) ◽  
pp. 1725-1747 ◽  
Author(s):  
Kiwoong Jin ◽  
Ho Choi ◽  
Yoshiaki Nakano
Keyword(s):  
Compressive Strain ◽  
Concrete Block ◽  
Unreinforced Masonry ◽  
School Buildings ◽  
Rc Frame ◽  
Rc Frames ◽  
Equivalent Strut ◽  
Lateral Strength ◽  
Curvature Distribution ◽  
Typical School

In this study, RC frames with unreinforced masonry (URM) infill for typical school buildings in Korea are experimentally investigated to evaluate their seismic performance. For this purpose, one-bay, one-fourth scale specimens, with unreinforced concrete block (CB) infill having different boundary conditions due to beam rigidity, are tested under in-plane cyclic loading, using a distinctive measurement scheme consisting of three-axis strain gauges attached to all CB units. In this paper, the diagonal strut mechanism of CB infill including its main strut angle, average compressive strain, and equivalent strut width is discussed using principal compressive strains on CB units. The lateral strength carried by CB infill and RC frame from the overall response of the specimens is also explained, based on the compressive stress acting on the infill and the curvature distribution along RC members during the test.

Lateral Load Behavior of an Open-Ground-Story RC Building with AAC Infills in Upper Stories

2016 ◽  
Vol 32 (3) ◽  
pp. 1653-1674 ◽  
Author(s):  
Supratik Bose ◽  
Durgesh C. Rai
Keyword(s):  
Brick Masonry ◽  
Hysteretic Behavior ◽  
Analytical Models ◽  
Rc Frame ◽  
Masonry Infills ◽  
Rc Frames ◽  
Open Ground ◽  
Strength And Stiffness ◽  
Infilled Rc Frames ◽  
Masonry Infilled Rc Frames

Autoclaved aerated concrete (AAC) masonry infills in upper stories can be beneficial for improving the seismic response of open-ground-story (OGS), reinforced concrete (RC)–frame buildings. Two reduced 1:2.5-scale models of single-story, single-bay RC frames with and without AAC infill masonry were tested for resistance properties and hysteretic behavior. Low strength and stiffness of AAC masonry, about half of the conventional brick masonry, led to improved load sharing between the infill and the frame, which helped an early development of frame yield mechanism for enhanced energy dissipation. Test results were used to evaluate the reliability of using existing strength and stiffness relations of conventional masonry infilled RC frames for AAC infilled frames. Analytical models were developed to predict the observed hysteretic behavior of tested specimens. Nonlinear analyses of a five-story, four-bay OGS-RC frame were performed for conventional brick masonry infills and relatively softer and weaker AAC infills in upper stories. The results indicated that the undesirable effect of weak/soft ground story mechanism of OGS-RC frames can be reduced to an acceptable level by using AAC infills in upper stories.

scholarly journals Seismic performance of brick masonry infilled frame structures with bed joint reinforcements

2020 ◽  
Vol 156 ◽  
pp. 03004
Author(s):  
Maidiawati ◽  
Jafril Tanjung ◽  
Yulia Hayati ◽  
Agus ◽  
Satria Rangga
Keyword(s):  
Seismic Performance ◽  
Frame Structure ◽  
Frame Structures ◽  
Rc Frame ◽  
Infilled Frame ◽  
Rc Frames ◽  
Lateral Strength ◽  
Plane Direction ◽  
Infilled Rc Frames ◽  
Reversed Cyclic

This paper presents the evaluation of the seismic performance of brick infilled RC frame structures with bed joint reinforcements based on reversed cyclic lateral load tests. Three specimens of the structural model of 1/4 scale-down single-story single-bay brick infilled RC frame was prepared, which were brick infilled RC frames with and without bed joint reinforcements. Two specimens of brick infills with bed joint reinforcements were different in the spacing of bed joint rebars. The specimens were tested by applying a reversed cyclic lateral loading in-plane direction. During the tests, the crack propagation was observed at the peak and residual drifts of each loading cycle to recognize the failure mechanisms of the specimens. As the results, although the use of the bed joint reinforcements ineffective to increase the lateral strength of the overall infilled frame structure. The rebars in mortar bed joints role to sustain the lateral strength in plastic deformation, and provide the whole structure with high ductility. It seemed that the rebars in mortar bed joints confined the brick infills. Therefore, the infilled RC frames can survive in large deformation without failure of the infills in out of the plane direction.

An Experimental Study on Reinforced Concrete Infilled Frames with Openings

2013 ◽  
Vol 747 ◽  
pp. 429-432 ◽  
Author(s):  
Fatih Suleyman Balik ◽  
Hasan Husnu Korkmaz ◽  
Mehmet Kamanli ◽  
Fatih Bahadir ◽  
Serra Zerrin Korkmaz ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Experimental Studies ◽  
Rc Buildings ◽  
Concrete Frames ◽  
Rc Frames ◽  
Lateral Strength ◽  
Structural Failures ◽  
Strength And Stiffness ◽  
Recent Earthquakes ◽  
Infilled Rc Frames

In the last decade, seven major earthquakes caused significant casualties and extensive structural failures. Thousands of RC buildings were severely damaged or collapsed in Turkey due to various deficiencies. This has initiated experimental studies on strengthening methods and intensive researches regarding the rehabilitation of reinforced concrete structures by introducing reinforced concrete infill walls were carried out. Strengthening of reinforced concrete frames by cast-in-place reinforced concrete infills is commonly used in practice. Many structures were also repaired using this technique after the recent earthquakes. In this experimental research, six, one-bay/two-story, 1/3-scaled non-ductile, undamaged reinforced concrete (RC) frames were constructed and tested to investigate the behavior of frames strengthened by introducing infills with or without openings. The test specimens were subjected to reversed cyclic quasi-static lateral loading. The specimens were constructed with the most commonly observed deficiencies in residential RC buildings in Turkey. The first specimen was the reference bare specimen and contained no strengthening. The other specimens were infilled with RC panels with openings having different ratios and configurations. Strength, stiffness and storey drifts of the test specimens were measured and compared. Test results indicated that infilled RC frames displayed significantly higher lateral strength and stiffness than the non-ductile bare frame considerably.

Seismic Performance of Story Drift–Controlled RC Frames with Hysteretic Dampers

2012 ◽  
Vol 28 (4) ◽  
pp. 1569-1587
Author(s):  
Juan Andres Oviedo-Amezquita ◽  
Mitsumasa Midorikawa ◽  
Tetsuhiro Asari
Keyword(s):  
Mechanical Properties ◽  
Energy Dissipation ◽  
Seismic Performance ◽  
Analytical Procedure ◽  
Seismic Damage ◽  
Rc Frame ◽  
Rc Frames ◽  
Wide Range ◽  
Story Drift ◽  
Hysteretic Dampers

This paper investigates the seismic performance of story drift–controlled reinforced concrete (RC) frames with hysteretic dampers. The frame models include a wide range of mechanical properties of dampers, which are defined according to a proportion rule in order to explicitly control the yield story drift of dampers. The story drift response, hysteretic energy dissipation and other parameters are examined to evaluate the effectiveness of dampers. The influence of the global flexural deformation of the frame on the response of dampers is also examined, and an analytical procedure to account for this phenomenon is developed. The obtained results indicate that the seismic performance of the structure is improved by reducing the story drift demand and seismic damage uniformly over the building height. Regarding the global flexural deformation, the proposed analytical procedure can be used for a preliminary estimation of the story number up to which dampers yield before the RC frame.

scholarly journals Seismic Strengthening of RC Structures Using Wall-Type Kagome Damping System

Buildings ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 41
Author(s):  
Moo-Won Hur ◽  
Yonghun Lee ◽  
Min-Jun Jeon ◽  
Sang-Hyun Lee
Keyword(s):  
Energy Dissipation ◽  
Yield Strength ◽  
Shear Loading ◽  
Seismic Retrofitting ◽  
Rc Frame ◽  
Metallic Wire ◽  
Cyclic Shear ◽  
Loading Tests ◽  
Energy Dissipation Capacity ◽  
Strength And Stiffness

In this study, the Kagome truss damper, a metallic wire structures, was introduced and its mechanical properties were investigated through theoretical analyses and experimental tests. The yield strength of the Kagome damper is dependent on the geometric shape and diameter of the metallic wire. The Kagome damper has higher resistance to plastic buckling as well as lower anisotropy. Cyclic shear loading tests were conducted to investigate the energy dissipation capacity and stiffness/strength degradation by repeated loadings. The hysteretic properties obtained from the tests suggest that a modification of the ideal truss model with a hinged connection could be used to predict the yield strength and stiffness of the damper. For seismic retrofitting of a low-rise RC moment frame system, a wall-type Kagome damping system (WKDS) was proposed. The effectiveness of the proposed system was verified by conducting cyclic loading tests using a RC frame with/without the WKDS (story drift ratio limit 1.0%). The test results indicated that both the strength and stiffness of the RC frame increased to the target level and that its energy dissipation capacity was significantly enhanced. Nonlinear static and dynamic analyses were carried out to validate that the existing building structure can be effectively retrofitted using the proposed WKDS.

Seismic performance of RC frames strengthened by RC infill walls

2021 ◽  
pp. 136943322199772
Author(s):  
Shao-Ge Cheng ◽  
Yi-Xiu Zhu ◽  
Wei-Ping Zhang
Keyword(s):  
Masonry Walls ◽  
Rc Frame ◽  
Seismic Line ◽  
Shake Table Tests ◽  
Infill Walls ◽  
Displacement Ductility ◽  
Rc Frames ◽  
Story Drift ◽  
Comparison Of The Results ◽  
Bending Failure

This study presents the shake-table tests of a 1/5-scaled RC frame retrofitted with RC infill walls. The intensity of input ground motions increased gradually to comprehensively evaluate the structural seismic behavior. We performed a comparison of the results from the RC frame with masonry walls and that with RC walls. The results showed that the presence of RC infills effectively improved the lateral structural stiffness and loading capacity of the frames and reduced their damage and story drift. RC walls acted as the first seismic line of defense, and their failure was dominated by bending failure and concentrated on the low stories. The displacement ductility of the structure decreased with increasing stiffness of the introducing infills.

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