Stiffness Reduction Factors for Geometric and Material Nonlinearity of Reinforced Concrete Beams and Columns subject to Short Term Loading

2009 ◽  
Author(s):  
A.C. Sousa ◽  
M. Pereira ◽  
R.C. Barros
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Material Nonlinearity ◽  
Reinforced Concrete Beams ◽  
Short Term ◽  
Stiffness Reduction ◽  
Reduction Factors

scholarly journals Experimental Analysis of the Strengthening of Reinforced Concrete Beams in Shear Using Steel Plates

2018 ◽  
Vol 3 (4) ◽  
pp. 52 ◽  
Author(s):  
Marília Batti ◽  
Bruno Silva ◽  
Ângela Piccinini ◽  
Daiane Godinho ◽  
Elaine Antunes
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Concrete Beams ◽  
Point Load ◽  
Reinforced Concrete Beams ◽  
Steel Plates ◽  
Short Term ◽  
Before And After ◽  
Underlying Causes ◽  
Structural Adhesive

In some situations, it is necessary to strengthen or rehabilitate a structure in the short term, but before doing so, a critical analysis of the underlying causes is required to find the best technique to solve the problem. The structural strengthening is used to increase an element’s ability to resist a stress when it no longer meets the original conditions or new necessities of use due to faults, deterioration, thermal variations, and lack of maintenance. The present article aims to evaluate the strengthening of reinforced concrete beams with 0.75 mm thick SAE 1020 steel plates bonded with epoxy-based structural adhesive. The steel plates were attached to the sheared area before and after the beams were taken to the breaking point load. According to the results, it was possible to conclude the effectiveness of the strengthening applied to healthy beams that had its bearing capacity increased up to 50%. The beam that was strengthened after the shear, with a fissure that was restored with epoxy-based structural adhesive, had its load bearing capacity increased by 49.2%. The beams with fissures that were filled with mortar had their bearing capacity decreased by 58.70% if compared with the reference beams, and thus they presented an unsatisfactory performance.

Deflection Calculation on Reinforced Concrete Beams Strengthened by Externally Prestressing Transverse Tensioning Method

2013 ◽  
Vol 671-674 ◽  
pp. 430-436
Author(s):  
Jin Jun Liu ◽  
Tian Wen Wang
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Large Error ◽  
Reinforced Concrete Beams ◽  
Secondary Effect ◽  
Test Results ◽  
Short Term ◽  
Secondary Load ◽  
Externally Prestressing ◽  
Good Agreement

Eight reinforced concrete beams (six externally reinforced and two contrast beams) were tested under primary or secondary load experiment. According to the test results, the existing specifications were applied to make calculations on short-term deflection which leaded to a large error. The secondary effect should be considered on calculating the deflection. Therefore, comparisons were made between the improved calculated value and test value on deflections of reinforced concrete beams strengthened by externally prestressed transverse tensioning method and they are in good agreement.

Experimental Studies of Reinforced Concrete and Fiber-Reinforced Concrete Beams with Short-Term and Long-Term Loads

2019 ◽  
Vol 968 ◽  
pp. 227-233 ◽  
Author(s):  
Stepan Neutov ◽  
Maryna Sydorchuk ◽  
Mykola Surianinov
Keyword(s):  
Reinforced Concrete ◽  
Steel Fiber ◽  
Concrete Beams ◽  
Experimental Studies ◽  
Fiber Reinforced Concrete ◽  
Reinforced Concrete Beams ◽  
Short Term ◽  
Ordinary Concrete ◽  
Fiber Concrete ◽  
Steel Fiber Concrete

Experimental studies of the stress-strain state of reinforced concrete and fiber-reinforced concrete beams under short-term and long-term loads were carried out. The tests were carried out on three series of beams of different types - from ordinary concrete, steel fiber concrete and combined section, when the lower zone of the beam with a height of0.5his made of steel fiber concrete, and the upper one is made of ordinary concrete. During short-term loading, the load was applied in steps with a 10-minute exposure at each step to failure or to a predetermined level of a continuously acting load. In the interval between the steps, the process of cracking was tracked. After reaching a given level of loading, the load was fixed and maintained unchanged with a spring cassette for 300 days. Deformations were measured using strain gauges and dial gauges. Deflections and relative deformations of the extreme upper and extreme lower fibers for three types of beams are determined. It has been established that stabilization of deflections in beams from steel fiber concrete occurs much earlier (100 days) than in beams made of ordinary concrete (175 days). Studies have shown that the beams of ordinary concrete in the process of long-acting load lowered the carrying capacity by 5.5%. The bearing capacity of steel concrete beams, in contrast, increased by 7.6%.

On the Experimental Analysis of Temperature Influence on Stiffness of Reinforced Concrete Beams

2015 ◽  
Vol 6 (1) ◽  
pp. 49-58 ◽  
Author(s):  
Robert Kowalski ◽  
Michal Glowacki ◽  
Marian Abramowicz
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Cross Sections ◽  
Concrete Beams ◽  
Rectangular Cross Section ◽  
Thermal Strain ◽  
Bending Moment ◽  
Reinforced Concrete Beams ◽  
Stiffness Reduction ◽  
Tensile Zone

The paper presents results of experimental research whose main topic was determination of stiffness reduction in bent reinforced concrete beams in two cases: when only tensioned or only compressed zone was exposed to high temperature. Twenty four reinforced concrete beams with rectangular cross-section were prepared for the experiment. Eight groups of beams were prepared in total: 2 with reinforcement ratio - 0.44 and 1.13% x 2 levels of load - 50 or 70% of destructive force ensuring the constant value of bending moment in the centre part of heated beams x 2 static schemes. Three beams were used in each group. Significant cross-section stiffness reduction was observed in beams where the tensile zone was heated. This was due to considerable elongation of the bars where the steel load elongation summed up with the free thermal strain. In beams where the compressed zone was heated the stiffness reduction was observed only after the time where the tensile zone heated cross-sections were already destroyed.

Shear Strength of Reinforced Concrete Beams after Fire

2012 ◽  
Vol 256-259 ◽  
pp. 742-748 ◽  
Author(s):  
Kai Xiang ◽  
Guo Hui Wang ◽  
Hua Xin Liu
Keyword(s):  
Reinforced Concrete ◽  
Calculation Method ◽  
Concrete Beams ◽  
Shear Capacity ◽  
Reinforced Concrete Beams ◽  
Rc Beams ◽  
Test Analysis ◽  
Concentrated Load ◽  
Transfer Mechanisms ◽  
Reduction Factors

In order to research the calculation method of shear capacity for fire-damaged reinforced concrete (RC) beams, the reason of drop of shear capacity was analyzed from material properties and transfer mechanisms of RC beams after fire. Formulas of shear capacity were suggested for fire-damaged RC beams. Based on test analysis, the values of reduction factors of shear capacity were proposed under concentrated load. The results show that suggested calculation method is capable of predicting shear capacity of fire-damaged RC beams exactly. The values of reduction factors of shear capacity need further experiments research.

scholarly journals Experimental Study on Calculation Methods for Short-term Cracks in High-strength Reinforced Concrete Beams

2017 ◽  
Vol 11 (1) ◽  
pp. 187-194
Author(s):  
Ruliang Zheng ◽  
Degao Tang ◽  
Yulong Xue ◽  
Zhen Liao
Keyword(s):  
Reinforced Concrete ◽  
Crack Width ◽  
Concrete Beams ◽  
High Strength ◽  
Crack Spacing ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Calculation Methods ◽  
Short Term ◽  
Average Crack

High-strength steel has increasingly become widely used among various engineering practices, but the relevant provisions of the codes lag behind its development. Six sets of experiments on simple supported beams reinforced with HTB600 and HTB700 rebars subject to bending loading were conducted in this study to 1) investigate the conditions of crack development, 2) contrast the calculating modes of short-term crack width between Chinese and European concrete codes, and 3) analyze European applicability and precision pertaining to high-strength reinforcement of beams. According to the experiments and research, when the calculation formulae obtained from Chinese codes were used to calculate the average crack spacing of high-strength reinforced concrete beams, the error relative to that obtained in the experiment reached approximately 20%. Based on this, a revised formula for the calculation of average crack spacing is proposed in this article, and the results of these calculations align with the results obtained from the experiment. In addition, this study also demonstrates that the maximum cracking spacing calculated by adhering to Eurocode standards yielded no significant deviation as compared to the experimental results. However, owing to a difference in the crack width exceeding 20% being observed between the results obtained under Eurocode standards and the experimental results, the calculation methods need to be further improved for better applicability of high-strength reinforced rebars.

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