scholarly journals Strengthening of vulnerable RC moment resisting frames using direct internal connection of X-steel bracing

2021 ◽  
Author(s):  
Siavash Sadeghinezhad ◽  
Ali Kheyroddin ◽  
Alireza Mortezaei
Keyword(s):  
Reinforced Concrete ◽  
Large Scale ◽  
Concrete Frames ◽  
Reinforced Concrete Frame ◽  
Gusset Plate ◽  
Concrete Frame ◽  
Soft Story ◽  
Internal Connection ◽  
Panel Zone ◽  
Moment Resisting

Non-ductile reinforced concrete frames are commonly found in older buildings in many parts of the world. These structures designed for gravity loads, have limited lateral strength and ductility, are prone to excessive one-way lateral movement and soft-story mechanism. This paper focuses on the retrofit of an existing reinforced concrete frame, using steel X-braces by direct internal connection method. The main purpose is the analytical study of general behavior and response of large scale vulnerable frames. An experimental study was used to validate the numerical modeling performed in ABAQUS. Next the base samples were retrofitted with X-braces and four proposed direct internal connection methods. Furthermore, in a separate parametric studies, the effect of frame type, bracing cross-section dimensions and gusset plate shape were investigated. The results indicated that the stiffness, bearing capacity and absorbed energy of the reinforced concrete frame by using steel X-braces increases up to 4, 2.3 and 1.5 times, respectively. Moreover, bracing acts like the first defense system against lateral loads, such as structural fuse with its yield, increases the amount of energy dissipation. It also removes the plastic hinges by reducing the ultimate displacement and stress of lateral load in the panel zone.

Experimental Investigation and Crack Resistance Analysis on Large Scale Prestressed Steel Reinforced Concrete Frame

2011 ◽  
Vol 255-260 ◽  
pp. 524-528
Author(s):  
Xue Yu Xiong ◽  
Feng Gao ◽  
Yang Li
Keyword(s):  
Reinforced Concrete ◽  
Large Scale ◽  
Concrete Structures ◽  
Engineering Application ◽  
Concrete Frames ◽  
Reinforced Concrete Frame ◽  
Static Test ◽  
Concrete Frame ◽  
Concrete Members ◽  
Axial Forces

Based on the static test of large-scaled prestressed steel concrete frames, the behavior of crack were tested and investigated. In this paper, according to theory of reinforced concrete members, Code for design of concrete structures(GB 50010-2002)and code ACI 318—05, the formulas of cracking moment considering secondary axial forces were deduced and verified by test results. Conclusion can be drawn as follow: the calculation errors of formulas derive from theory of reinforced concrete members is small, generally less than 6%; the errors of formulas referring to Code for design of concrete structures(GB 50010-2002)is about 10%, which is satisfy the needs of engineering and simply to be calculated; Cracking moment calculated by formulas referring to code ACI 318—05 is less than test result, it is unsafe for engineering application.

Seismic risk for commercial buildings in Memphis

1983 ◽  
Vol 73 (5) ◽  
pp. 1435-1450
Author(s):  
Andrzej S. Nowak ◽  
Elizabeth L. M. Rose
Keyword(s):  
Reinforced Concrete ◽  
Seismic Risk ◽  
Steel Structure ◽  
Structural Type ◽  
Commercial Buildings ◽  
Concrete Frames ◽  
Reinforced Concrete Frame ◽  
Damage Prediction ◽  
Concrete Frame

Abstract This paper deals with the evaluation of seismic risk for commercial buildings in Memphis, Tennessee. The seismicity of the area is summarized, and commercial buildings are divided into categories with regard to parameters such as number of stories, year of construction, assessed value, total floor area, and structural type. The distributions of these parameters are presented in the figures. During the study, over 15 buildings were examined on site by a team of experts to evaluate their seismic resistances. The quality of the design, materials, and construction was found to be surprisingly good, particularly in those structures built since 1900. Seismic resistance is analytically evaluated for five buildings: a four-story reinforced concrete frame; a four-story steel structure with vertical trusses; a 13-story stell frame; and two multi-story reinforced concrete frames. The loadings from four sources are considered: EI Centro and Taft earthquakes in California (1940 and 1952, respectively) and the forces specified in the 1979 UBC and 1981 BOCA codes. Ratios of load to capacity are calculated. For each building considered, the expected percentage of damage is evaluated for the two earthquakes. The damage prediction is extended to all commercial buildings in Memphis.

Seismic performance of ductile medium height reinforced concrete frame buildings designed in accordance with the provisions of the 1995 National Building Code of Canada

1999 ◽  
Vol 26 (5) ◽  
pp. 606-617 ◽  
Author(s):  
A C Heidebrecht ◽  
N Naumoski
Keyword(s):  
Reinforced Concrete ◽  
Seismic Performance ◽  
Frame Structure ◽  
Performance Criteria ◽  
Building Code ◽  
Reinforced Concrete Frame ◽  
Concrete Frame ◽  
Moment Resisting Frame ◽  
Moment Resisting ◽  
Interstorey Drift

This paper describes an investigation into the seismic performance of a six-storey ductile moment-resisting frame structure located in Vancouver and designed and detailed in accordance with the seismic provisions of the National Building Code of Canada (1995). Both pushover and dynamic analyses are conducted using an inelastic model of the structure as designed and detailed. The structural performance of a number of design variations is evaluated using interstorey drift and member curvature ductility response as performance measures. All frames studied are expected to perform at an operational level when subjected to design level seismic excitations and to meet life safe performance criteria at excitations of twice the design level.Key words: seismic, building, frames, ductile, design, performance, reinforced concrete, code.

scholarly journals Experimental Study on Seismic Retrofitting of Reinforced Concrete Frames Using Welded Concrete-Filled Steel Tubes

2020 ◽  
Vol 10 (20) ◽  
pp. 7061 ◽  
Author(s):  
Kyong Min Ro ◽  
Min Sook Kim ◽  
Young Hak Lee
Keyword(s):  
Reinforced Concrete ◽  
Seismic Performance ◽  
Seismic Energy ◽  
Maximum Load ◽  
Steel Tube ◽  
Seismic Retrofitting ◽  
Reinforced Concrete Frame ◽  
Concrete Frame ◽  
Moment Resisting Frames ◽  
Moment Resisting

Buildings constructed with non-seismic details are at risk of damage and collapse when an earthquake occurs due to a lack of strength, stiffness, and ductility. For reinforced concrete (RC) moment-resisting frames, seismic retrofitting methods that can enhance strength or ductility should be applied. However, such strategies have many disadvantages related to constructability, serviceability, securing integrity, and cost. In this paper, a welded concrete-filled steel tube (WCFST) system was examined in order to resolve the problems of the existing seismic retrofitting methods for RC moment-resisting frames. To evaluate the seismic performance of the proposed system, two specimens, one with non-seismic details and another reinforced with a WCFST seismic system, were manufactured for the cyclic loading tests. As a result of the experiments, the specimen retrofitted with the WCFST system showed maximum load, effective stiffness, and energy dissipation capacity values approximately 3, 2, and 2.5 times greater, respectively, than those obtained from the existing reinforced concrete frame specimen. The experimental results indicate that the proposed WCFST system is expected to be effective at improving the seismic performance by enhancing both the strength of the existing reinforced concrete frame structures and the dissipation of the seismic energy.

Multi-Type Finite Elements Hybrid Model for Simulating Global Behavior of Reinforced Concrete Frames in Fires

2013 ◽  
Vol 353-356 ◽  
pp. 2357-2361
Author(s):  
Yong Jun Liu ◽  
Yang Yang Liu ◽  
Ran Bi ◽  
Jing Hai Zhou
Keyword(s):  
Reinforced Concrete ◽  
Finite Elements ◽  
Hybrid Model ◽  
Large Scale ◽  
Research Work ◽  
Concrete Structures ◽  
Concrete Frames ◽  
Reinforced Concrete Frame ◽  
Element Analysis ◽  
Reinforced Concrete Frames

In general, reinforced concrete frames have excellent fire resistance properties, but more and more concrete buildings collapsed in fires. The majority of past research work on the response of concrete building to fire has looked at the effects of fire upon individual structural members, and most commonly when subjected to heating from standard fire tests. At present, the fire behaviors of whole reinforced concrete frame are not adequately understood. There is a great need for development of models which consider the effects of fire on the whole structure under more realistic heating regimes. There is also a fundamental requirement for further large-scale testing of concrete structures, to observe the behavior of whole concrete structures in real fires and also for validation of advanced computer analysis tools. Accuracy and efficiency are two major concerns in finite element analysis of structural response of concrete frames in fires. In this paper, a multi-type finite elements hybrid model for simulating structural behavior of whole reinforced concrete frames in real fire is suggested.

scholarly journals Shake Table Response of Unreinforced Masonry and Reinforced Concrete Elements of Special Moment Resisting Frame

2019 ◽  
Vol 2019 ◽  
pp. 1-17 ◽  
Author(s):  
Syed Azmat Ali Shah ◽  
Junaid Shah Khan ◽  
Syed Muhammad Ali ◽  
Khan Shahzada ◽  
Waqar Ahmad ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Seismic Performance ◽  
Masonry Wall ◽  
Masonry Walls ◽  
Shake Table ◽  
Base Excitation ◽  
Reinforced Concrete Frame ◽  
Infill Walls ◽  
Concrete Frame ◽  
Moment Resisting

Half-scaled reinforced concrete frame of two storeys and two bays with unreinforced masonry (URM) infill walls was subjected to base excitation on a shake table for seismic performance evaluation. Considering the high seismic hazard Zone IV of Pakistan, reinforcement detailing in the RC frame is provided according to special moment resisting frames (SMFRs) requirement of Building Code of Pakistan Seismic-Provisions (BCP SP-2007). The reinforced concrete frame was infilled with in-plane solid masonry walls in its interior frame, in-plane masonry walls with door and window openings in the exterior frame, out-of-plane solid masonry wall, and masonry wall with door and window openings in its interior frame. For seismic capacity qualification test, the structure was subjected to three runs of unidirectional base excitation with increasing intensity. For system identification, ambient-free vibration tests were performed at different stages of experiment. Seismic performance of brick masonry infill walls in reinforced concrete frame structures was evaluated. During the shake table test, performance of URM infill walls was satisfactory until design ground acceleration was 0.40g with a global drift of 0.23%. The test was continued till 1.24g of base acceleration. This paper presents key findings from the shake table tests, including the qualitative damage observations and quantitative force-displacement, and hysteretic response of the test specimen at different levels of excitation. Experimental results of this test will serve as a benchmark for validation of numerical and analytical models.

Experimental and Numerical Studies on the Reinforced Concrete Frames Subjected to Blast Loads

2012 ◽  
Vol 157-158 ◽  
pp. 1173-1177
Author(s):  
Li Xiao ◽  
Wen Zhong Qu ◽  
Jian Gang Wang
Keyword(s):  
Reinforced Concrete ◽  
Numerical Models ◽  
Computer Code ◽  
Economic Loss ◽  
Frame Structure ◽  
Building Structures ◽  
Concrete Frames ◽  
Reinforced Concrete Frame ◽  
Concrete Frame ◽  
Blast Response

Terrorist bombing attacks will endanger and may even destroy the target building structures, resulting in economic loss and casualties. Typical columns and floor slab systems are not designed to resist the complex blast loading. So, in recent years, the effects of blast on conventional public buildings are focused on. In this paper,a two-bay,one-story reinforced concrete frame structure which is used to model a portion of a typical reinforced concrete frame structural system is used to investigate the blast response. The experiments are conducted on two models, allowing a variation in explosives standoff and explosives charge. In each experiment,the blast pressure values are recorded and the degree of damage of the frames are studied. According to the two kinds of experiments, two numerical models are established. ALE method which considers the interaction of the explosive, the air, and the structure is applied.Structure response analyses are performed using the large deformation finite-element computer code, LS-DYNA. The numerical results are compared with the experiment results, and a good agreement is obtained. The calculating results also demonstrate that some experimental value is unreasonable.

Rehabilitation of Reinforce Concrete Frames with Reinforced Concrete Infills

2006 ◽  
Vol 324-325 ◽  
pp. 635-638
Author(s):  
Chang Sik Choi ◽  
Hye Yeon Lee
Keyword(s):  
Reinforced Concrete ◽  
Resistance Mechanism ◽  
Reinforce Concrete ◽  
Structural Performance ◽  
Concrete Frames ◽  
Initial Stiffness ◽  
Reinforced Concrete Frame ◽  
Infill Wall ◽  
Concrete Frame ◽  
Lightly Reinforced Concrete

The purpose of this study is to understand the fundamental resistance mechanism and the shear strength of the frame with the reinforced concrete infill wall by comparing analytical with experimental results. For this, one-story and one-bay four specimens were manufactured with variables; Lightly Reinforced Concrete Frame (LRCF), monolith placing Shear Wall (SW), CIP Infill Wall (CIW-1) and CIP Infill Wall reinforced with diagonal rebar (CIW-2). The addition of the RC infill wall was significantly improved the strength and the stiffness. Compared with specimen LRCF, ultimate strength and initial stiffness of infills was improved 4 and 6 times, respectively. The case of specimen CIW-2, structural performance was improved remarkably by placing a diagonal rebar.

scholarly journals Dynamic increase factor in reinforced concrete frames under disproportionate collapse

2017 ◽  
Author(s):  
◽  
Joseph Ernest Kirby
Keyword(s):  
Reinforced Concrete ◽  
Concrete Frames ◽  
Reinforced Concrete Frame ◽  
Catenary Action ◽  
Sudden Loss ◽  
Dynamic Increase Factor ◽  
Concrete Frame ◽  
Disproportionate Collapse ◽  
Live Loads ◽  
Internal Forces

Under a disproportionate collapse, the sudden loss of a support causes a dynamic response that can amplify the internal forces in the surrounding members and lead to significant global damage. This study considered a two-dimensional, quarter scale, two bay, two story reinforced concrete frame with discontinuous reinforcement. In order to simulate an interior bay condition, the frame was axially restrained at the adjacent-bay beam locations. Dead weights were applied to simulate the dead and live loads expected to be present during a collapse event. To initiate the test, and to simulate the sudden loss of a load-bearing column, a kickstand was implemented. The results presented herein are from four dynamic tests under various levels of applied load. The fourth drop, with a load corresponding to 42 percent of the 1.2*DL + 0.5*LL typically specified in disproportionate collapse guidelines, resulted in a catenary action. The results show that there is a very fine tipping point at which the structure is pushed past the compressive arch and flexural range of resistance into the catenary action range (hereafter referred to as the snap-through effect). Furthermore, the results show that due to this snap-through effect, the dynamic increase factor can be as great as 2.4, significantly higher than the value specified by the aforementioned guidelines.

The shearing performance of a beam-column joint in a reinforced concrete frame subjected to bidirectional loading

2019 ◽  
Vol 22 (15) ◽  
pp. 3176-3189
Author(s):  
Zhenbao Li ◽  
Yanwei Cui ◽  
Kun Song ◽  
Hua Ma ◽  
Zhenyun Tang
Keyword(s):  
Reinforced Concrete ◽  
Calculation Model ◽  
Shear Capacity ◽  
Detailed Calculation ◽  
Concrete Frames ◽  
Reinforced Concrete Frame ◽  
Concrete Frame ◽  
Shear Mechanism ◽  
Column Joint ◽  
Reinforced Concrete Frame Structures

The anti-seismic capability of beam-column joints in reinforced concrete frame structures undergoing bidirectional loading may be lower than the designed capability for unidirectional earthquake action. To date, detailed calculation methods for the shear capability and shearing performance for joints in reinforced concrete frames subjected to bidirectional loading have not been reported. In this work, the shear mechanism of the beam-column joint in a reinforced concrete frame under bidirectional loading is analyzed. The study shows that when a synthetic shear force is imposed on the joint, the oblique compression zone comes into being at the corner of the joint, and the oblique compression strut is formed in the core area of the joint, which is different from the shear mechanism of the joint under unidirectional loading. A shear capacity calculation model is established based on the strut-and-tie model. Through the testing of reinforced concrete frame joints under bidirectional monotonous loading, the combined shear and deformation in the joint are obtained, the mechanical properties in each principal plane and in the combined shear action plane are analyzed, the shearing performance of the joints in a reinforced concrete frame under bidirectional loading is defined, and the shear contributions of hoop and column reinforcement are verified. The predicted values of the shear capability in this work are in good agreement with the reported experimental results.

Sign in / Sign up

Export Citation Format

Share Document