scholarly journals Impact Resistance Behavior of Reinforced Concrete Beams Deteriorated due to Repeated Freezing and Thawing

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Yusuke Kurihashi ◽  
Yoshinori Nonomura ◽  
Hisashi Konno
Keyword(s):  
Propagation Velocity ◽  
Impact Resistance ◽  
Frost Damage ◽  
Rc Beam ◽  
Rc Beams ◽  
Residual Deflection ◽  
Rc Structures ◽  
Freeze Thaw ◽  
Ultrasonic Propagation ◽  
The Impact

Many existing reinforced concrete (RC) structures constructed more than 50 years ago now require maintenance. This is especially true in cold, snowy regions where significant frost damage deterioration of RC structures becomes a severe problem. In this study, falling-weight impact tests were performed to investigate the impact resistance behavior of RC beams degraded by frost damage. An RC beam was subjected to approximately 900 freeze-thaw cycles to emulate the frost damage before the execution of the impact test. The surface of the beam was remarkably scaled, and its coarse aggregate was exposed. The degree of deterioration was evaluated by the distribution of ultrasonic propagation velocity. The following conclusions were drawn. (1) The ultrasonic propagation velocity of RC beams was significantly reduced following 872 freeze-thaw cycles. At the upper edge of the RC beam, the ultrasonic wave propagation velocity decreased from 4,000 m/s to 1,500 m/s in some parts. This corresponds to a relative dynamic elastic modulus of approximately 14%. (2) The residual deflection of RC beams with frost damage increased at most by 20% compared with beams without frost damage. The increase in residual deflection was primarily related to the peeling of concrete at the collision site and the opening of multiple bending cracks. (3) According to the existing residual deflection calculation formula, an increase of 20% in the residual deflection corresponds to a decrease of about 17% in the bending capacity of the RC beam. When the relationship between the degree of frost damage deterioration and the impact resistance of RC structures is defined, existing structures subjected to accidental impact force from rockfalls are safer and can be maintained more efficiently.

Impact Resistant Behavior of RC Beam Damaged by Freeze-Thaw Action

2016 ◽  
Vol 711 ◽  
pp. 745-750
Author(s):  
Yusuke Kurihashi ◽  
Maki Mizuta ◽  
Akinori Shimata ◽  
Norimitsu Kishi
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Frost Damage ◽  
Rc Beam ◽  
Input Energy ◽  
Rc Beams ◽  
Freeze Thaw ◽  
Weight Impact ◽  
Falling Weight ◽  
The Impact

In this study, in order to investigate the impact resistant behavior of RC beams damaged by freeze-thaw action, falling-weight impact tests for RC beams were conducted taking with/without frost damage as variable. The RC beam used in this study has been damaged by accelerated freeze-thaw cycling. From this experiment, following results were obtained: 1) Elastic modulus and compressive strength of the concrete were decreased due to freeze-thaw action; 2) In the case of damaged beam, many fine cracks were occurred in small input energy; and 3) Deflections of damaged beam was larger than that of non-damaged beam at the same weight-falling height.

scholarly journals Strengthening Effect of CFRP Sheets and Steel Fibers for Enhancing the Impact Resistance of RC Beams

2011 ◽  
Vol 11 (5) ◽  
pp. 41-47
Author(s):  
Mi-Hye Kim ◽  
Kyung-Hwan Min ◽  
Doo-Yeol Yoo ◽  
Young-Soo Yoon
Keyword(s):  
Impact Resistance ◽  
Steel Fibers ◽  
Strengthening Effect ◽  
Rc Beams ◽  
Cfrp Sheets ◽  
The Impact

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 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.

scholarly journals FLEXURAL CAPACITY ASSESSMENT OF BRICK AGGREGATED PRE-CRACKED RC BEAM STRENGTHENED WITH CARBON FIBER POLYMER

2019 ◽  
Vol 31 (1) ◽  
Author(s):  
Niaz Md Mamun ◽  
G. M. Sadiqul Islam ◽  
Md Jahangir Alam
Keyword(s):  
Carbon Fiber ◽  
Failure Modes ◽  
Fiber Reinforced Polymers ◽  
Capacity Assessment ◽  
Rc Beam ◽  
Rc Beams ◽  
Flexural Capacity ◽  
Carbon Fiber Reinforced Polymers ◽  
Rc Structures ◽  
Fiber Sheet

Ageing and improvements to design code has led to many existing RC structures made of locally available brick aggregates are now found structurally deficient and are in need of rehabilitation. This research emphases on flexural capacity assessment and investigation of failure modes of Carbon Fiber Reinforced Polymers (CFRP) strengthened brick aggregated RC beams. Flexural performance of the RC beam specimens are evaluated using four point bending method. Six RC beams (initially cracked) with CFRP strengthening were tested by varying (i) type of CFRP, (ii) reinforcing area, (iii) anchorage type; and (iv) number of CFRP layers. Two beams were tested as control specimens. Unidirectional carbon fiber sheet (Tow Sheet) and individually hardened continuous fiber strands woven into sheet form (Strand Sheet) were used. Simple flexure failure was obtained for unstrengthened RC beams while end plate and interfacial debonding were observed for the initially cracked CFRP strengthened RC beams. Strengthening of pre-cracked beams using Strand Sheet gave better performance compared to Tow sheet. Overall flexural strength improvement of CFRP strengthened beams varied from 12% to 34% with respect to unstrengthened beams depending on strengthening methods.

scholarly journals Embodied Energy and Cost Optimization of RC Beam under Blast Load

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Runqing Yu ◽  
Diandian Zhang ◽  
Haichun Yan
Keyword(s):  
Unit Volume ◽  
Cost Optimization ◽  
Optimization Procedure ◽  
Embodied Energy ◽  
Cost Ratio ◽  
Rc Beam ◽  
Rc Beams ◽  
Rc Structures ◽  
Important Index ◽  
The Cost

Reinforced concrete (RC) structures not only consume a lot of resources but also cause continuing pollution. However, sustainable design could make RC structures more environmental-friendly. One important index for environmental impact assessment is embodied energy. The aim of the present study is to optimize the embodied energy and the cost of RC beam subjected to the blast loads. First, a general optimization procedure was described. Then, the optimization procedure was used to optimize the embodied energy and the cost of RC beams. Optimization results of the cost and the embodied energy were compared. It was found that the optimization results were influenced by the cost ratio nC (ratio of price of steel to price of concrete per unit volume) and the embodied energy ratio nE (ratio of embodied energy of steel to embodied energy of concrete per unit volume). An optimal design that minimized both embodied energy and cost simultaneously was obtained if values of nC and nE were very close.

BEHAVIOR OF RC BEAM RETROFITTED USING ULTRA HIGH-PERFORMANCE CONCRETE UNDER IMPACT LOADS

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Mohammed Ali Al-Osta
Keyword(s):  
Finite Element ◽  
Impact Loading ◽  
High Performance ◽  
High Performance Concrete ◽  
Rc Beam ◽  
Rc Beams ◽  
Ultra High Performance Concrete ◽  
Static Loads ◽  
Finite Element Software ◽  
The Impact

Several new types of materials have recently been used as retrofitting materials for structural elements such as ultra-high performance concrete with steel fiber reinforcement (UHPFRC). These materials are used as jacking to enhance the strength and ductility reinforced concrete (RC) beams. Considerable attention has been focused on the response of retrofitted RC beam under static loads but the behavior of such beam under impact loading is somewhat lacking. Therefore, in this study, a 3-D finite element model (FEM) of retrofitted RC beams under impact loading using non-linear finite element software (ABAQUS) was investigated. Since experimental work on this topic is scarce, the FEM is validated using the results of retrofitted RC beam under static loads. The impact load was applied in ABAQUS as equivalent to an initial velocity of 2500 mm/s. A parametric study was carried out to study the flexural response of RC beams retrofitted with different thicknesses and strengthening configurations of UHPFRC under impact loading.

Experimental Study on the Fatigue Properties of RC Beam Strengthened by Prestressed CFL

2008 ◽  
Vol 33-37 ◽  
pp. 169-173 ◽  
Author(s):  
Yi Yang ◽  
Pei Yan Huang ◽  
Jun Deng
Keyword(s):  
Experimental Study ◽  
Experimental Results ◽  
Fatigue Properties ◽  
Rc Beam ◽  
Rc Beams ◽  
Rc Structures ◽  
Reinforcing Effect

Bonding prestressed CFL to strengthen reinforced RC structures can improve the bending capability of structures and the working efficient of CFL. Base on the fatigue experiments of 4 RC beams strengthened by prestressed CFL, the present paper analyzes the fatigue properties of prestressed CFL reinforced RC beams. Comparing with the experimental results of strengthened RC beams without prestress, it can be concluded that the prestressed technology can improve the reinforcing effect and fatigue lives.

Experimental Investigation on Shear Property of RC Beams with Aramid Fiber Mesh Stirrups

2011 ◽  
Vol 255-260 ◽  
pp. 20-24 ◽  
Author(s):  
Er Jun Wu ◽  
Jian Long Xing ◽  
Zhao Quan Zhu
Keyword(s):  
High Performance ◽  
Aramid Fiber ◽  
Rc Beam ◽  
Rc Beams ◽  
Rc Structures ◽  
High Durability ◽  
Shear Property ◽  
Shear Bearing Capacity ◽  
Fiber Mesh ◽  
Better Than

This paper develops a new-typed high-durability RC structures in which the steel stirrups are replaced by mesh stirrups weaved with soft high performance fiber belt. The experiments are carried out to investigate the shear property of six beams with soft aramid fiber mesh stirrups and one common RC beam and the results show that the failure state in the slope sections of the RC beams with fiber belt mesh stirrups is similar to the common RC beam. It was also found the shear property of beams with lean fiber mesh stirrups is better than that with vertical and horizontal mesh stirrups, and with the high-elastic- modulus fiber stirrups better than the low-elastic-modulus’s. In addition, the distributions of fiber stirrups strain at slope section are also observed. Based the experimental results, a model for beams with fiber mesh stirrups was established and the formula of shear bearing capacity was suggested.

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