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 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 Impact Resisting Mechanisms of Shear-Critical Reinforced Concrete Beams Strengthened with High-Performance FRC

2020 ◽  
Vol 10 (9) ◽  
pp. 3154
Author(s):  
Carlos Zanuy ◽  
Gonzalo S.D. Ulzurrun
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
Fiber Reinforced Concrete ◽  
Reinforced Concrete Beams ◽  
Environmental Cost ◽  
Interface Debonding ◽  
Rc Beams ◽  
Rc Structures ◽  
High Performance Fiber ◽  
The Impact

Reinforced concrete (RC) structures typically present brittle failures by shear or punching under impact loading. High-performance fiber-reinforced concrete (HPFRC) has great potential due to its superior strength and energy absorption. The higher price and environmental cost of HPFRC compared to conventional RC can be effectively overcome by partially strengthening impact-sensitive RC members with HPFRC. To study the feasibility of this technique, HPFRC was applied as a tensile layer at the bottom of RC beams. Drop weight impact tests were carried out on beams with two values (35 and 55 mm) of HPFRC thickness, in addition to companion RC beams. Results show that the impact response can be divided into two stages: a first stage governed by local effects and shear plug formation at midspan, and a second stage governed by global beam behavior with formation of shear web cracks. A new resisting mechanism was observed for beams strengthened with HPFRC, as the strengthening layer worked similarly to a stress ribbon retaining the damaged RC and reducing fragmentation-induced debris. Such mechanism was fully achieved by the specimens with 35 mm HPFRC layer but was limited for the specimens with 55 mm HPFRC layer due to impact-induced interface debonding.

Optimum Design of Reinforced Concrete Beams

2020 ◽  
pp. 71-91
Keyword(s):  
Reinforced Concrete ◽  
Optimum Design ◽  
Nonlinear Behavior ◽  
Optimization Method ◽  
Reinforced Concrete Beams ◽  
Metaheuristic Algorithms ◽  
Rc Beam ◽  
Rc Structures ◽  
Eurocode 2 ◽  
The Cost

The design of reinforced concrete (RC) beams need special conditions to provide a ductile design. In this design, the maximum amount of tensile reinforcement must be limited to singly reinforced design. After the singly reinforced limit, the cost of doubly reinforced RC beam rapidly increases, and it may not be an optimum design. To consider this nonlinear behavior and other rules used in RC structures according to regulations such as ACI 318: Building code requirements for structural concrete and Eurocode 2: Design of concrete structures, an algorithmic and iteration optimization method is needed. In this chapter, two examples are presented, and optimum results are shared for methodologies employing several metaheuristic algorithms. The importance of using metaheuristic algorithms can be seen in this chapter.

scholarly journals Statistical and Reliability Study on Shear Strength of Recycled Coarse Aggregate Reinforced Concrete Beams

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3321
Author(s):  
Hyunjin Ju ◽  
Meirzhan Yerzhanov ◽  
Alina Serik ◽  
Deuckhang Lee ◽  
Jong R. Kim
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Construction Material ◽  
Safety Margin ◽  
Shear Capacity ◽  
Reinforced Concrete Beams ◽  
Construction And Demolition Waste ◽  
Demolition Waste ◽  
Rc Structures ◽  
Coarse Aggregates

The consumption of structural concrete in the construction industry is rapidly growing, and concrete will remain the main construction material for increasing urbanization all over the world in the near future. Meanwhile, construction and demolition waste from concrete structures is also leading to a significant environmental problem. Therefore, a proper sustainable solution is needed to address this environmental concern. One of the solutions can be using recycled coarse aggregates (RCA) in reinforced concrete (RC) structures. Extensive research has been conducted in this area in recent years. However, the usage of RCA concrete in the industry is still limited due to the absence of structural regulations appropriate to the RCA concrete. This study addresses a safety margin of RCA concrete beams in terms of shear capacity which is comparable to natural coarse aggregates (NCA) concrete beams. To this end, a database for reinforced concrete beams made of recycled coarse aggregates with and without shear reinforcement was established, collecting the shear specimens available from various works in the existing literature. The database was used to statistically identify the strength margin between RCA and NCA concrete beams and to calculate its safety margin based on reliability analysis. Moreover, a comparability study of RCA beams was conducted with its control specimens and with a database for conventional RC beams.

Repair of Severely Damaged Reinforced Concrete Beams with High-Strength Cementitious Grout

2020 ◽  
Vol 2674 (6) ◽  
pp. 372-384
Author(s):  
Antoine N. Gergess ◽  
Mahfoud Shaikh Al Shabab ◽  
Razane Massouh
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Cementitious Materials ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Reinforced Concrete Beams ◽  
Rc Beams ◽  
Rc Structures

High-strength cementitious materials such as high-performance concrete are extensively used for retrofit of reinforced concrete (RC) structures. The effectiveness of these materials is increased when mixed with steel fibers. A commonly used technique for strengthening and repair of RC beams consists of applying high-performance fiber-reinforced concrete jackets around the beam perimeter. This paper investigates the jacketing method for repairing severely damaged RC beams. Four 2 m (6 ft 63/4 in.) long rectangular RC beams, 200 × 300 mm (8 ×12 in.) were initially cast and loaded until failure based on three-point bending tests. The four beams were then repaired by thickening the sides of the damaged RC beams using a commercially available high-strength shrinkage grout with and without steel fibers. Strain and deformation were recorded in the damaged and repaired beams to compare structural performance. It is shown that the flexural strength of the repaired beams is increased and the crack pattern under loading is improved, proving that the proposed repair method can restore the resistance capacity of RC beams despite the degree of damage. A method for repair is proposed and an analytical investigation is also performed to understand the structural behavior of the repaired beams based on different thickening configurations.

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.

Effect of cracking localization on the structural ductility of normal strength and high strength reinforced concrete beams with steel fibers

2019 ◽  
Vol 10 (4) ◽  
pp. 457-469 ◽  
Author(s):  
Avraham N Dancygier ◽  
Yuri S Karinski
Keyword(s):  
Reinforced Concrete ◽  
Transition Point ◽  
Concrete Beams ◽  
High Strength ◽  
Reinforcement Ratio ◽  
Steel Fibers ◽  
Reinforced Concrete Beams ◽  
Flexural Ductility ◽  
Ductility Ratio ◽  
The Impact

This article presents a study of cracking localization in normal and high strength concrete beams that include steel fibers and the influence of this localization on their structural ductility. It is shown that for a given fiber type and content, as the reinforcement ratio ρ decreases, the cracking localization level increases. The effect of ρ on the level of cracking localization is more pronounced for low amounts of conventional reinforcement. This range of conventional reinforcement ratio is typical of slabs and especially for the commonly thicker protective slabs. Examination of the effect of the reinforcement ratio on the flexural ductility shows that there exists a transition point below which the ductility ratio decreases with  ρ. This transition point is well above the minimum reinforcement ratio, which is required in design codes for plain reinforced concrete elements. Empirical analysis of the relation between cracking localization and ductility ratio shows that up to the same transition point, as cracking localization increases, the flexural ductility decreases. Findings of this study show that the positive effect of adding fibers on enhancing the impact resistance of slabs and beams is conflicted by their negative influence on reducing the structural ductility for low reinforcement ratios, which are typical of protective slabs.

Propagation Behavior of Main Crack in Reinforced Concrete Beams Strengthened with CFRP under Cyclic Bending Load

2013 ◽  
Vol 535-536 ◽  
pp. 205-208
Author(s):  
Zheng Wei Li ◽  
Pei Yan Huang ◽  
Hao Zhou
Keyword(s):  
Reinforced Concrete ◽  
Crack Propagation ◽  
Main Crack ◽  
Fatigue Behavior ◽  
Propagation Rate ◽  
Reinforced Concrete Beams ◽  
Rc Beam ◽  
Cyclic Bending ◽  
Propagation Behavior ◽  
Bending Load

Fatigue behavior of reinforced concrete (RC) beam can be improved by externally bonded fiber reinforced polymer (FRP). However, propagation behavior of a crack on the RC beam will have serious effect on the fatigue life of the beam strengthened with FRP. In this paper, a finite element (FE) procedure was developed to analysis the stress intensity factor (SIF) of the main crack and an experimental study was conducted to investigate the propagation rate of the main crack of the RC beam strengthened with carbon fiber laminate (CFL) under cyclic bending load. The FE analysis results show that the SIF near the main crack tip increases at the beginning and then decreases with the fatigue crack propagation. When relative crack length α is equal to 0.3, the SIF is maximum. When α approaches 0.75, the SIF approaches zero. A total of 3 RC beams strengthened with CFL were tested. The experimental results show that it is possible to divide the process of the crack propagation into three distinct phases, including crack initiation and then quickly propagation, stable propagation and then rest and unstable propagation. A semi-empirical equation based on the Paris Law was developed to predict the crack propagation rate.

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