scholarly journals Experimental and Numerical Investigation of Self Compacting Reinforced Concrete Dapped End Beams Strengthened with CFRP Sheets

2018 ◽  
Vol 26 (7) ◽  
pp. 16-35
Author(s):  
Qasim Mohammed Shakir ◽  
Baneen Basim Abd ◽  
Ali Talib Jasim
Keyword(s):  
Reinforced Concrete ◽  
Failure Load ◽  
Load Capacity ◽  
Experimental Tests ◽  
Experimental Program ◽  
Cfrp Sheets ◽  
Strut And Tie ◽  
Strut And Tie Model ◽  
Cracked Specimens ◽  
Good Agreement

This study aims to investigate experimentally the behavior of self-compacting reinforced concrete dapped end beams strengthened with CFRP sheets and, then theoretically by ANSYS 15.0 software. The experimental program consists of testing 14-specimens each of dimensions (200x400x1500 mm) with two values of Shear span to depth effective (a/d), namely (1.5 and 1.0). Two of the beams are a control beams (with full reinforcement), and four beams with reduced reinforcement in hanger and nib regions. The other beams have been strengthened with several configurations by CFRP sheets for the same values of (a/d), the comparison between results included load-deflection curves and cracked specimens. It was found that the strut and tie model (STM) is very conservative somehow, reduction the nib reinforcements by about (60%), in reduction in failure load by about (35% and 15%) for the two values of (a/d). With respect to the strengthened specimens, it observed that the strengthening with inclined CFRP strips (450) yielded better results in comparison with other configurations. The improvement in load capacity was about (23%) for (a/d=1.5 and 1.0). Also, it is found that the nonlinear model adopted in the present work compered the experimental tests yielded a good agreement with difference of about (12%).

scholarly journals Stiffness and Strength Analysis of Flexural RC beams strengthened with CFRP Sheets Considering the Influence of Pre-cracking

Mechanika ◽  
2020 ◽  
Vol 26 (4) ◽  
pp. 277-284
Author(s):  
Tadas LISAUSKAS ◽  
Mindaugas AUGONIS ◽  
Tadas ZINGAILA ◽  
Mario Rui Tiago ARRUDA
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beam ◽  
Reinforced Concrete Beam ◽  
Reinforced Concrete Beams ◽  
Bending Test ◽  
Experimental Program ◽  
Strength Analysis ◽  
Rc Beams ◽  
Cfrp Sheets ◽  
Good Agreement

                           This paper presents experimental, numerical and analytical analysis of newly cast and pre-cracking flexural reinforced concrete beams strengthened with CFRP. In total, 9 intermediate-scale composite beams were cast and tested using 4-point bending test setup. Midspan deflection, width of the cracks, concrete and CFRP strains were measured during the experimental program. Clear efficiency of composite pre-cracked beams was observed in comparison to newly cast beams: enhanced flexural capacity and increased stiffness after appearance of primary cracks in tension zone. Good agreement was found comparing experimental and theoretical (EC2) deflections of RC beams strengthened with CFRP. However, for more detailed verification, the analysis should be extended with more specimens. The shear stress at the end of CFRP sheets between the concrete and CFRP increased rapidly until reaching maximum slip value, when the reinforced concrete beam strengthened with CFRP reaches 60-90 % utilization of load bearing capacity. All experimental results were compared with numerical and analytical calculations. Experimental, numerical and analytical results were in sufficiently good agreement.

An evaluation of pile cap design methods in accordance with the Canadian design standard

2004 ◽  
Vol 31 (1) ◽  
pp. 109-119 ◽  
Author(s):  
William Cavers ◽  
Gordon A Fenton
Keyword(s):  
Reinforced Concrete ◽  
Structural Design ◽  
Design Methods ◽  
Building Codes ◽  
Design Models ◽  
Design Standard ◽  
Strut And Tie ◽  
Pile Cap ◽  
Pile Caps ◽  
Strut And Tie Model

There are a number of design methods that have been described for the design of pile caps, but there has been no consensus on which method provides the best approach for the working designer. This paper describes a study conducted to establish the performance of several pile cap design methods, particularly with respect to the Canadian standard, CSA A23.3-94. Previous research was examined to determine the basis of the design methods and the state of current research. The design methods identified were then applied to pile caps for which test data were available. The theoretical loads obtained using the various design methods were compared with the experimental loads. The results of this study indicate that two design models of the five examined are the most suitable. This study also indicates that the provisions of the Canadian design standard are adequate. A possible refinement of the strut-and-tie model incorporating a geometric limit is also outlined.Key words: building codes, footings, pile caps, reinforced concrete, structural design.

Influence of the Parameter of Ductility of Reinforcing Steel on the Behaviour of a Narrow Three-Span Reinforced Concrete Slab Based on Experimental Investigations

2015 ◽  
Vol 240 ◽  
pp. 218-224 ◽  
Author(s):  
Mirosław Wieczorek
Keyword(s):  
Reinforced Concrete ◽  
Concrete Slab ◽  
Load Capacity ◽  
Experimental Tests ◽  
Experimental Investigations ◽  
Building Structures ◽  
Reinforced Concrete Slab ◽  
Tension Member ◽  
Test Models ◽  
Reinforced Steel

In the time of the exploitation of building structures frequently situations do occur, in which due to failures they are exposed to much higher loads than has been originally predicted. In a state of emergency due to overloading of the structure, significant reserves of load capacity may be appear in the case of a self-acting tension member work. The aim of the paper was to demonstrate the influence of reinforced steel parameters and its quantity on the mechanism of destruction of four three-span models of reinforced concrete strips with the dimensions 7140×500×190 mm. The paper contains the description of the test stand and test models and the results of experimental tests which were compared with the results of the calculations based on traditional methods.

Study on Mechanical Behaviors and Calculation of Shear Strength of Steel Truss Reinforced Concrete Deep Beams

2011 ◽  
Vol 243-249 ◽  
pp. 514-520
Author(s):  
Chun Yang ◽  
Ming Ji He ◽  
Jian Cai ◽  
Yan Sheng Huang ◽  
Yi Wu
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Experimental Investigations ◽  
Deep Beam ◽  
Deep Beams ◽  
Steel Reinforced Concrete ◽  
Strut And Tie ◽  
Steel Truss ◽  
Mechanical Performances ◽  
Strut And Tie Model

Based on strut-and-tie model (STM) in deep beams, steel truss reinforced concrete (STRC) deep beam was developed. Experimental investigations of mechanical performances of STRC deep beams were carried out, and results show that STRC deep beam is of high ultimate bearing capacity, large rigidity and good ductility; Strut-and-tie force transference model is formed in STRC deep beams, and loads can be transferred in the shortest and direct way. Then Steel reinforced concrete (SRC) strut-and-tie model (SSTM) for determining the shear strength of STRC deep beams is proposed. The contribution of SRC diagonal strut, longitudinal reinforcements, stirrups and web reinforcements to the shear strength of STRC deep beams are determined with consideration of softened effects of concrete, and for safe consideration, superposition theory is employed for SRC struts. Computer programs are developed to calculate the shear strength of STRC deep beams and verified by experimental results.

Shear Strength Prediction of Reinforced Concrete Deep Beams Using Strut-and-Tie Model

2014 ◽  
Vol 931-932 ◽  
pp. 468-472
Author(s):  
Piyoros Tasenhod ◽  
Jaruek Teerawong
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Failure Modes ◽  
Reinforced Concrete Beams ◽  
Strength Prediction ◽  
Test Results ◽  
Shear Span ◽  
Strut And Tie ◽  
Effective Depth ◽  
Strut And Tie Model

Shear strength prediction of simple deep reinforced concrete beams by method of strut-and-tie model is presented in this paper. The tested specimens were designed according to Appendix A of ACI 318-11 code with variations of shear span-to-effective depth ratios and ratios of horizontal and vertical crack-controlling reinforcement. Test results revealed that at the same shear span-to-effective depth ratio, the various crack-controlling reinforcements significantly influenced on strength reduction coefficients of strut and failure modes. When the shear span-to-effective depth ratios were increased, failure modes changed from splitting diagonal strut to flexural-shear failure. Based on the test results, the proposed model was compared with Appendix A of ACI 318-11code.

Experimental Study on Deep Four-Pile Caps with Different Reinforcement Layouts Based on 3D Strut-and-Tie Analogy

2008 ◽  
Vol 400-402 ◽  
pp. 917-922 ◽  
Author(s):  
Qian Gu ◽  
Cheng Fang Sun ◽  
Shao Min Peng
Keyword(s):  
Load Capacity ◽  
Longitudinal Reinforcement ◽  
Test Results ◽  
Test Procedures ◽  
Strut And Tie ◽  
Pile Cap ◽  
Scale Ratio ◽  
Pile Caps ◽  
Strut And Tie Model ◽  
Distributed Reinforcement

Based on 3D strut-and-tie analogy developed for analyzing the load-transferring mechanism of deep pile cap, this paper focuses on the effect of different longitudinal reinforcement layouts at the lower part of cap on the mechanical behaviors of deep four-pile cap. Besides a common layout of uniformly distributed reinforcement by the flexural theory, three different layouts of concentrated reinforcement over piles were designed by 3D strut-and-tie analogy. All specimens were limited in same reinforcement percentages, dimensions, materials and test procedures. Four specimens with the scale ratio of 1/5 were tested under the statically incremental gravity loading. The load capacity, deflection, strain of longitudinal reinforcement of specimens were measured, and the failure mode, crack propagation, deformation of specimens and stress distribution of reinforcement were analyzed. Through comparisons of the test results among all specimens, it was found that deep pile cap failed in shear and corner-pile punching whether with concentrated or uniform reinforcement, and the reinforcement concentrated over each two adjacent piles, similar to the tension bars in the strut-and-tie model, had considerable advantages than common uniform reinforcement layout. The ultimate strength of deep pile cap with concentrated reinforcement was significantly increased, while the improvement of deformation resistance and brittleness of deep pile cap was limited. According to above findings, the appropriate reinforcement layouts for deep pile cap were suggested in this paper.

scholarly journals Influence of Multiple Openings on Reinforced Concrete Outrigger Walls in a Tall Building

2019 ◽  
Vol 9 (22) ◽  
pp. 4913 ◽  
Author(s):  
Han-Soo Kim ◽  
Yi-Tao Huang ◽  
Hui-Jing Jin
Keyword(s):  
Reinforced Concrete ◽  
Structural Model ◽  
Lateral Displacement ◽  
Tall Buildings ◽  
Structural Performance ◽  
Element Analysis ◽  
Wall Area ◽  
Strut And Tie ◽  
Equivalent Bending Stiffness ◽  
Strut And Tie Model

Outrigger systems have been used to control the lateral displacement of tall buildings. Reinforced concrete (R.C.) outrigger walls with openings can be used to replace conventional steel outrigger trusses. In this paper, a structural model for an R.C. outrigger wall with multiple openings was proposed, and the effects of the multiple openings on the stiffness and strength of the outrigger walls were evaluated. The equivalent bending stiffness of the outrigger wall was derived to predict the lateral displacement at the top of tall buildings and internal shear force developed in the wall. The openings for the passageway in the wall were designed by the strut-and-tie model. The stiffness and strength of the outrigger wall with multiple openings was analyzed by the nonlinear finite element analysis. Taking into consideration the degradation in stiffness and strength, the ratio of the opening area to the outrigger wall area is recommended to be less than 20%. The degradation of stiffness due to openings does not affect the structural performance of the outrigger system when the outrigger has already large stiffness as the case of reinforced concrete outrigger walls.

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