Torsional strength of reinforced concrete beams

2000 ◽  
Vol 27 (3) ◽  
pp. 445-453 ◽  
Author(s):  
Khaldoun N Rahal
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Pure Shear ◽  
Concrete Strength ◽  
Reinforced Concrete Beams ◽  
Axial Loads ◽  
Simple Method ◽  
Torsional Strength ◽  
Mode Of Failure ◽  
Good Agreement

A simple method for predicting the ultimate strength and mode of failure of reinforced concrete beams subjected to pure torsion is presented. This method is an extension of a recently developed method for predicting the strength of membrane elements subjected to pure shear that was also applied to beams subjected to combined shearing forces, bending moments, and axial loads. The torsional strength is related to the amounts of transverse and longitudinal reinforcement and to the concrete strength. To check the adequacy of this simple method, the calculated strength and mode of failure are checked against the experimental results of 66 beam tests available in the literature, and good agreement is found. The simplicity of the method is illustrated by an example.Key words: beams, building codes, mode of failure, reinforced concrete, shear, strength, torsion.

Laboratory Fast Corrosion Test of Plain Steel Bars in Concrete Beams

2012 ◽  
Vol 535-537 ◽  
pp. 1803-1806
Author(s):  
Shun Bo Zhao ◽  
Peng Bing Hou ◽  
Fu Lai Qu
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Numerical Models ◽  
Concrete Strength ◽  
Reinforced Concrete Beams ◽  
Uniform Corrosion ◽  
Pure Bending ◽  
Accelerated Corrosion ◽  
Steel Bars ◽  
Bending Length

An experimental study was carried out to examine the non-uniform corrosion of plain steel bars in reinforced concrete beams partially placed in 5% sodium chloride solution under conditions of accelerated corrosion. 4 reinforced concrete beams with different concrete strength were made. The crack distributions of the beams due to pre-loads and expansion of corrosion product, and the sectional corrosion characteristics of plain steel bars are described in detail. The sectional area loss relating to mass loss and change along pure bending length of the beams are discussed. These can be used as the basis of test for further studies to build the numerical models of serviceability of corroded reinforced concrete beams.

Prediction Scheme of Torsional Strength of Reinforced Concrete Beam

2012 ◽  
Vol 214 ◽  
pp. 306-310
Author(s):  
Han Chen Huang
Keyword(s):  
Genetic Algorithm ◽  
Reinforced Concrete ◽  
Concrete Beam ◽  
Concrete Beams ◽  
Reinforced Concrete Beam ◽  
Reinforced Concrete Beams ◽  
Ann Model ◽  
Torsional Strength ◽  
Prediction Scheme ◽  
Optimal Network

This study proposes a artificial neural network with genetic algorithm (GA-ANN) for predicting the torsional strength of reinforced concrete beam. Genetic algorithm is used to the optimal network structure and parameters. A database of the torsional failure of reinforced concrete beams with a rectangular section subjected to pure torsion was obtained from existing literature for analysis. This study compare the predictions of the GA-ANN model with the ACI 318 code used for analyzing the torsional strength of reinforced concrete beam. The results show that the proposed model provides reasonable predictions of the ultimate torsional strength of reinforced concrete beams and offers superior torsion accuracy compared to that of the ACI 318-89 equation.

scholarly journals Seismic Behaviors of Concrete Beams Reinforced with Steel-FRP Composite Bars under Quasi-Static Loading

2018 ◽  
Vol 8 (10) ◽  
pp. 1913 ◽  
Author(s):  
Tong-Liang Xiao ◽  
Hong-Xing Qiu ◽  
Jia-Le Li
Keyword(s):  
Reinforced Concrete ◽  
Seismic Performance ◽  
Concrete Beams ◽  
Concrete Strength ◽  
Reinforced Concrete Beams ◽  
Ultimate Capacity ◽  
Shear Span ◽  
Frp Composite ◽  
Drift Ratio ◽  
Seismic Behaviors

Steel-fiber reinforced polymer (FRP) composite bar (SFCB) is a new composite material with good corrosion resistance and designable post-yield stiffness. Substitution of steel bar with SFCB can greatly increase the durability and ultimate capacity associated with seismic performance. First, the method and main results of the experiment are briefly introduced, then a simplified constitutive model of composite bar material was applied to simulate the seismic behaviors of the concrete beams reinforced with SFCBs by fiber element modeling. The simulation results were found to be in good agreement with test results, indicating that the finite element model is reasonable and accurate in simulating the seismic behaviors of beams reinforced with SFCB. Based on the numerical simulation method, a parametric study was then conducted. The main variable parameters were the FRP type in composite bars (i.e., basalt, carbon FRP and E-glass FRP), the concrete strength, basalt FRP (BFRP) content in SFCBs and shear span ratio. Seismic behaviors such as load-displacement pushover curves, seismic ultimate capacity and its corresponding drift ratio of the SFCBs reinforced concrete beams were also evaluated. The results showed that (1) the fiber type of the composite bar had a great impact on the mechanical properties of the beam, among which the beam reinforced with BFRP composite bar has higher seismic ultimate capacity and better ductility. With the increase of the fiber bundle in the composite bar, the post-yield stiffness and ultimate capacity of the component increase and the ductility is better; (2) at the pre-yield stage, concrete strength has little influence on the seismic performance of concrete beams while after yielding, the seismic ultimate capacity and post-yielding stiffness of specimens increased slowly with the increase in concrete strength, however, the ductility was reduced accordingly; (3) as the shear span ratio of beams increased from 3.5 to 5.5, the seismic ultimate capacity decreased gradually while the ultimate drift ratio increased by more than 50%. Through judicious setting of the fiber content and shear span ratio of the composite bar reinforced concrete beam, concrete beams reinforced with composite bars can have good ductility while maintaining high seismic ultimate capacity.

scholarly journals Assessing the Instantaneous Stiffness of Cracked Reinforced Concrete Beams Based on a Gradual Change in Strain Distributions

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Chunyu Fu ◽  
Dawei Tong ◽  
Yuyang Wang
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Cross Section ◽  
Concrete Beams ◽  
Internal Force ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Gradual Change ◽  
Concrete Cracking ◽  
Good Agreement

Concrete cracking causes a gradual change in strain distributions along the cross section height of reinforced concrete beams, which will finally affect their instantaneous stiffness. A method for assessing the stiffness is proposed based on the gradual change, which is considered through modeling different strain distributions for key sections in cracked regions. Internal force equilibria are adopted to find a solution to top strains and neutral axes in the models, and then the inertias of the key sections are calculated to assess the beam stiffness. The proposed method has been validated using experimental results obtained from tests on five reinforced concrete beams. The predicted stiffness and displacements are shown to provide a good agreement with experimental data. The instantaneous stiffness is proven to greatly depend on the crack number and depth. This dependence can be exactly reflected by the proposed method through simulating the gradual change in concrete strain distributions.

scholarly journals Shear behavior degradation and failure pattern of reinforced concrete beam with chloride-induced stirrup corrosion

2019 ◽  
Vol 22 (14) ◽  
pp. 2998-3010 ◽  
Author(s):  
Zhao-Hui Lu ◽  
Hai Li ◽  
Wengui Li ◽  
Yan-Gang Zhao ◽  
Zhuo Tang ◽  
...  
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Concrete Strength ◽  
Shear Behavior ◽  
Reinforced Concrete Beams ◽  
Failure Pattern ◽  
Reinforcement Corrosion ◽  
Shear Span ◽  
Depth Ratio

Reinforcement corrosion exhibits an adverse effect on the shear strength of reinforced concrete structures. In order to investigate the effects of chloride-induced corrosion of reinforcing steel on the shear behavior and failure pattern of reinforced concrete beams, a total of 24 reinforced concrete beams with different concrete strength grades and arrangements of stirrups were fabricated, among which 22 beams were subjected to accelerated corrosion to achieve different degrees of reinforcement corrosion. The failure pattern, crack propagation, load–displacement response, and ultimate strength of these beams were investigated under a standard four-point loading test in this study. Extensive comparative analysis was conducted to investigate the effects of the concrete strength, shear span-to-depth ratio, and stirrup type on the shear behavior of the corroded reinforced concrete beams. The results show that increasing the stirrup yielding strength is more effective in improving the shear strength of corroded reinforced concrete beams than that of concrete compressive strength. In terms of three types of stirrups, the shear strength of the beams with deformed HRB-335 is least sensitive to stirrup corrosion, followed by the beams with smooth HPB-235 and the beams with deformed HRB-400. The effect of the different stirrups on the shear strength depends on the corrosion degree of stirrup and shear span-to-depth ratio of the beam. The predicted results of shear strength of corroded reinforced concrete beams by a proposed analytical model are well consistent with the experimental results.

Calculation of Flexural Capacity of High-Strength Reinforced Concrete Beams Strengthened with FRP

2011 ◽  
Vol 71-78 ◽  
pp. 815-817 ◽  
Author(s):  
Jiong Feng Liang ◽  
Ze Ping Yang ◽  
Zhi Ming Qiu
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Engineering Application ◽  
High Strength ◽  
Correlation Equation ◽  
Reinforced Concrete Beams ◽  
Flexural Capacity ◽  
Different Types ◽  
Fiber Reinforce ◽  
Good Agreement

The mechanical properties of high-strength reinforced concrete beams strengthened with FRP ( fiber reinforce polymer) are further investigated theoretically including it s failure mechanism and loadability,based on earlier theoretical works on RC beams. And the correlation equation of flexural capacity on the cross section of high-strength reinforced concrete beams strengthened with FRP is deduced according to different types of failure.The correlation equation is shown to be in good agreement with the experimental results, which can be referred to engineering application.

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