scholarly journals Impact of Drying on Structural Performance of Reinforced Concrete Beam with Slab

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1887
Author(s):  
Pranjal Satya ◽  
Tatsuya Asai ◽  
Masaomi Teshigawara ◽  
Yo Hibino ◽  
Ippei Maruyama
Keyword(s):  
Reinforced Concrete ◽  
Drying Shrinkage ◽  
Reinforced Concrete Beam ◽  
Structural Performance ◽  
Rc Beam ◽  
Design Standards ◽  
Rc Structures ◽  
Load Displacement ◽  
Cyclic Loading Tests ◽  
The Impact

Evaluating the performance of reinforced concrete (RC) structures during earthquakes and the resultant damage in the structures depends on an accurate load–displacement relationship. Several experimental and analytical evaluation methods for load–displacement relationships have been proposed and specified in current design standards. However, there have been few quantitative studies on the impact of drying on the yielding behavior of RC members, including evaluations of the effective stiffness of members. In this study, to investigate changes in the mechanical properties of RC beam–slab members due to drying of the concrete, cyclic loading tests are conducted on two RC beam–slab members with and without drying. It is found that the lateral structural stiffness of the specimen with drying decreased to 77% that of the specimen without drying. This is verified in the calculation of the flexural stiffness. In this calculation, it is assumed that drying shrinkage decreases the moment of inertia of the slab in tension but not in compression. Meanwhile, no difference is observed in the flexural capacity and yield displacement between the two specimens. Thus, there is no significant impact from drying shrinkage in RC beam–slab members on the lateral structural performance, while the shrinkage instead induces greater flexural cracking, which reduces the residual stresses in the specimen with drift leading to a gradual decrease in the impact of drying.

scholarly journals Simplified Estimation Method for Maximum Deflection in Bending-Failure-Type Reinforced Concrete Beams Subjected to Collision Action and Its Application Range

2020 ◽  
Vol 10 (19) ◽  
pp. 6941 ◽  
Author(s):  
Yusuke Kurihashi ◽  
Hiroshi Masuya
Keyword(s):  
Reinforced Concrete ◽  
Estimation Method ◽  
Reinforced Concrete Beams ◽  
Rc Beam ◽  
Maximum Deflection ◽  
Simple Method ◽  
Rc Structures ◽  
Failure Type ◽  
Bending Failure ◽  
The Impact

As natural disasters have become increasingly severe, many structures designed to prevent rockfalls and landslides have been constructed in various areas. The impact resistance capacity of a reinforced concrete (RC) rock shed can be evaluated using its roof deflection. This study establishes a method for estimating the maximum deflection of a bending-failure-type RC beam, subjected to collisions that is based on the energy conservation concept—in which, the transmitted energy from a collision is equivalent to the energy absorbed by the beam. However, the following assumptions have never been confirmed: (1) The energy transmitted to the RC beam, due to the dropped weight, can be estimated by assuming a perfect plastic collision; and (2) the energy absorbed by the RC beam can be estimated by assuming plane conservation. In this study, these assumptions were verified using 134 previous test results of RC beams subject to weight collisions. In addition, we proposed a simple method for calculating the maximum deflection and its application scope. With this method, a performance-based impact-resistant design procedure for various RC structures can be established in the future. Moreover, this method will significantly improve the maintenance and management of existing RC structures subject to collisions.

scholarly journals Influence of Patching on the Shear Failure of Reinforced Concrete Beam without Stirrup

2021 ◽  
Vol 6 (7) ◽  
pp. 97
Author(s):  
Stefanus Adi Kristiawan ◽  
Halwan Alfisa Saifullah ◽  
Agus Supriyadi
Keyword(s):  
Reinforced Concrete ◽  
Shear Failure ◽  
Numerical Study ◽  
Unsaturated Polyester ◽  
Reinforced Concrete Beam ◽  
Concrete Cover ◽  
Shear Capacity ◽  
Rc Beam ◽  
Shear Span ◽  
Shear Cracking

Deteriorated concrete cover, e.g., spalling or delamination, especially when it occurs at the web of a reinforced concrete (RC) beam within the shear span, can reduce the shear capacity of the beam. Patching of this deteriorated area may be the best option to recover the shear capacity of the beam affected. For this purpose, unsaturated polyester resin mortar (UPR mortar) has been formulated. This research aims to investigate the efficacy of UPR mortar in limiting the shear cracking and so restoring the shear capacity of the deteriorated RC beam. The investigation is carried out by an experimental and numerical study. Two types of beams with a size of 150 × 250 × 1000 mm were prepared. The first type of beams was assigned as a normal beam. The other was a beam with a cut off in the non-stirrup shear span, which was eventually patched with UPR mortar. Two reinforcement ratios were assigned for each type of beams. The results show that UPR mortar is effective to hamper the propagation of diagonal cracks leading to increase the shear failure load by 15–20% compared to the reference (normal) beam. The increase of shear strength with the use of UPR mortar is consistently confirmed at various reinforcement ratios.

scholarly journals Toward Structural Health Monitoring of Civil Structures Based on Self-Sensing Concrete Nanocomposites: A Validation in a Reinforced-Concrete Beam

2021 ◽  
Vol 15 (1) ◽  
Author(s):  
Diego L. Castañeda-Saldarriaga ◽  
Joham Alvarez-Montoya ◽  
Vladimir Martínez-Tejada ◽  
Julián Sierra-Pérez
Keyword(s):  
Reinforced Concrete ◽  
Damage Detection ◽  
Direct Current ◽  
Health Monitoring ◽  
Electrical Resistance ◽  
Concrete Beam ◽  
Reinforced Concrete Beam ◽  
Structural Member ◽  
Rc Beam ◽  
Electric Resistance

AbstractSelf-sensing concrete materials, also known as smart concretes, are emerging as a promising technological development for the construction industry, where novel materials with the capability of providing information about the structural integrity while operating as a structural material are required. Despite progress in the field, there are issues related to the integration of these composites in full-scale structural members that need to be addressed before broad practical implementations. This article reports the manufacturing and multipurpose experimental characterization of a cement-based matrix (CBM) composite with carbon nanotube (CNT) inclusions and its integration inside a representative structural member. Methodologies based on current–voltage (I–V) curves, direct current (DC), and biphasic direct current (BDC) were used to study and characterize the electric resistance of the CNT/CBM composite. Their self-sensing behavior was studied using a compression test, while electric resistance measures were taken. To evaluate the damage detection capability, a CNT/CBM parallelepiped was embedded into a reinforced-concrete beam (RC beam) and tested under three-point bending. Principal finding includes the validation of the material’s piezoresistivity behavior and its suitability to be used as strain sensor. Also, test results showed that manufactured composites exhibit an Ohmic response. The embedded CNT/CBM material exhibited a dominant linear proportionality between electrical resistance values, load magnitude, and strain changes into the RC beam. Finally, a change in the global stiffness (associated with a damage occurrence on the beam) was successfully self-sensed using the manufactured sensor by means of the variation in the electrical resistance. These results demonstrate the potential of CNT/CBM composites to be used in real-world structural health monitoring (SHM) applications for damage detection by identifying changes in stiffness of the monitored structural member.

The Impact Load on a Reinforced Concrete Beam

2021 ◽  
pp. 199-245
Author(s):  
Farzad Hejazi ◽  
Hojjat Mohammadi Esfahani
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beam ◽  
Impact Load ◽  
Reinforced Concrete Beam ◽  
The Impact

Shear Failure of Patched Reinforced Concrete Beam without Web Reinforcements

2017 ◽  
Vol 737 ◽  
pp. 441-447 ◽  
Author(s):  
Stefanus Kristiawan ◽  
Agus Supriyadi ◽  
Senot Sangadji ◽  
Hapsara Brian Wicaksono
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beam ◽  
Shear Failure ◽  
Unsaturated Polyester ◽  
Reinforced Concrete Beam ◽  
Concrete Cover ◽  
Patch Repair ◽  
Rc Beam ◽  
Diagonal Crack ◽  
The Web

Degradation of reinforced concrete (RC) element could lead to a reduction of its strength and serviceability. The degradation may be identified in the form of spalling of concrete cover. For the case of RC beam, spalling of concrete cover could occur at the web of the shear span due to corrosion of the web reinfocements. The shear strength of the damaged-RC beam possibly will become less conservative compared to the corresponding flexural strength with a risk of brittle failure. Patch repair could be a choice to recover the size and strength of the damaged-RC beam. This research investigates the shear failure of patched RC beam without web reinforcements with a particular interest to compare the shear failure behaviour of patched RC beam and normal RC beam. The patch repair material used in this research was unsaturated polyester resin (UPR) mortar. The results indicate that the initial diagonal cracks leading to shear failure of patched RC beam occur at a lower level of loading. However, the patched RC beam could carry a greater load before the diagonal crack propagates in length and width causing the beam to fail in shear.

The Use of Recycled Aggregates in Continuously Reinforced Concrete Pavements (CRCP)

2013 ◽  
Vol 711 ◽  
pp. 391-395
Author(s):  
Hans de Backer
Keyword(s):  
Reinforced Concrete ◽  
Los Angeles ◽  
Drying Shrinkage ◽  
Recycled Aggregates ◽  
Concrete Layer ◽  
Los Angeles Test ◽  
Component Material ◽  
Ecological Importance ◽  
Natural Aggregates ◽  
The Impact

The use of recycled aggregates in concrete has increased in recent decades. Increasing scarcity of natural aggregates and the growing ecological importance promote this evolution. The first test section in Belgium of a two-layer continuously reinforced concrete pavement (CRCP) with recycled aggregates in the substrate layer was built on the highway E34/N49 in 2007. Horizontal cracking at the level of the reinforcement showed up after only a few years. This is a problem which was never seen before in CRCP and was probably due to the use of recycled aggregates. Therefore it is important to understand the impact of recycled aggregates on concrete. Recycled aggregates are a two-component material consisting of natural aggregates and adhering mortar. The adhering mortar is more porous than the rock particles which insures a higher water absorption and lower density. In addition, they have a lower abrasion loss in the Los Angeles-test and less resistance against weather and temperature changes. This is due to, respectively, the less strong mortar content, and the large pores of recycled granulates. A first cause of horizontal cracking can be found in the results of high drying shrinkage, high creep and low modulus of elasticity. These properties insure larger tensions in the concrete layer. In combination with a lower tensile strength it is a possible cause for the horizontal cracking. In addition, the paper reports on laboratory testing concerning the properties of concrete with recycled aggregates and discusses an alternative method to determine the concrete mixture which takes the influence of the adhering mortar into account.

Evaluation of Local Damage to Reinforced Concrete Panels Subjected to Oblique Impact of Rigid and Soft Missiles

2018 ◽  
Author(s):  
Akemi Nishida ◽  
Minoru Nagai ◽  
Haruji Tsubota ◽  
Yinsheng Li
Keyword(s):  
Reinforced Concrete ◽  
Simulation Method ◽  
Impact Angle ◽  
Oblique Impact ◽  
Local Damage ◽  
Empirical Formulas ◽  
Rc Structures ◽  
Impact Tests ◽  
Oblique Impacts ◽  
The Impact

Many empirical formulas have been proposed for evaluating local damage to reinforced concrete (RC) structures caused by impacts of rigid missiles. Most of these formulas have been derived based on impact tests normal to the target structures. Up to now, few impact tests oblique to the target structures have been carried out. This study has been conducted with the purpose of proposing a new formula for evaluating the local damage caused by oblique impacts based on previous experimental and simulation results. In this paper, the results of simulation analyses for evaluating the local damage to a RC panel subjected to normal and oblique impacts by rigid and soft missiles, by using the simulation method that was validated using the results of previous impact experiments. Based on the results of these simulation analyses, the effects of the rigidity of the missile as well as the impact angle on the local damage to the target structures are clarified.

FE Analysis on the Structural Behavior of Reinforced Concrete Beam Damaged by Fire

2013 ◽  
Vol 351-352 ◽  
pp. 743-746
Author(s):  
Soo Yeon Seo ◽  
Yu Gun Chung
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beam ◽  
Reinforced Concrete Beam ◽  
Fe Analysis ◽  
Structural Behavior ◽  
Rc Beam ◽  
Support Condition ◽  
Strength Deterioration ◽  
Simple Support ◽  
Analytical Result

This paper presents an analytical result about strength deterioration of reinforced concrete (RC) beams due to damage by fire. For the evaluation of the result, three RC beam specimens were made and two of those were exposed to fire. And then beam test was performed for those including non-heated specimen to evaluate the strength deterioration due to the fire damage under simple support condition. Strength decrease of materials due to the fire was evaluated through material test for concrete and reinforcements, respectively. Nonlinear Finite element (FE) analysis was performed by considering the decrease of materials due to fire. The analysis results showed that the structural behavior of fire-damaged RC beam was able to be simulated by using FE analysis with consideration of the reduction of material capacity due to fire.

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