scholarly journals Experimental Study of Large-scale RC Beams Shear-Strengthened with Basalt FRP Sheets

2020 ◽  
Vol 6 (4) ◽  
pp. 769-784
Author(s):  
Ahmed M. Sayed
Keyword(s):  
Large Scale ◽  
Ultimate Load ◽  
Experimental Studies ◽  
Beam Width ◽  
Lateral Strain ◽  
Width Ratio ◽  
Rc Beams ◽  
Frp Composite ◽  
Externally Bonded ◽  
New Variables

Over the last three decades, many experimental studies have been conducted to investigate the behavior of Reinforced Concrete (RC) beams, shear strengthened with externally bonded Fiber-Reinforced Polymer (FRP) composite. However, the majority of experimental studies have focused on small- to medium-scale beam specimens. As a result, most design equations that have been developed as part of these studies may thus not be accurate at predicting the shear strength of large-scale RC beams shear-strengthened with FRP sheets. This study thus involved performing tests on six specimens to study the effect of the larger scale, along with new variables such as beam width, new varieties of FRP sheets (basalt FRP (BFRP)), and the strengthening configuration (U-jacketing), on the prediction of the ultimate load of RC beams strengthened with externally bonded FRP composite. The experimental results were analyzed and showed that all these variables affected the lateral strain along the bottom and the top of the beams. It was found that variations in the depth to width ratio of the beams caused the failure angle to vary as well. For beams strengthened with BFRP sheets, both the cracking and ultimate load increased to 1.19 and 1.94 times the cracking and ultimate load of the control beams under identical conditions.

scholarly journals EFFECT OF WOVEN FABRIC ON THE SHEAR CAPACITY OF SHORT RC BEAMS

2003 ◽  
Vol 9 (3) ◽  
pp. 172-177
Author(s):  
Hau-yan Leung
Keyword(s):  
Woven Fabrics ◽  
Shear Capacity ◽  
Woven Fabric ◽  
Strengthening Effect ◽  
Rc Beams ◽  
Frp Composite ◽  
Externally Bonded ◽  
Fibre Reinforced Polymer ◽  
Shear Performance ◽  
Corrosion Problem

Recently, externally bonded fibre-reinforced polymer (FRP) composite plate has been used successfully to enhance the performance of reinforced concrete (RC) members. The non-corrosive property of FRP eliminates the corrosion problem, but the occurrence of premature cracking induced by the rigidity of FRP plates is still questionable. In current pilot study, woven fabric is adopted, in lieu of rigid plates, to provide the strengthening effect. An experimental programme was developed and a series of short RC model beams, including unloaded and preloaded specimens, were prepared and woven fabric straps were attached. Ultimate loading tests were earned out and the results were recorded. All specimens were specially designed to investigate the effect of woven fabric on the shear capacity of RC beams. The results demonstrate that the shear performance of both unpreloaded and preloaded RC members can be enhanced by more than 10 % if woven fabrics are employed.

Experimental study on the durability of FRP bars reinforced concrete beams in simulated ocean environment

2018 ◽  
Vol 25 (6) ◽  
pp. 1123-1134 ◽  
Author(s):  
Zhiqiang Dong ◽  
Gang Wu ◽  
Jinlong Lian
Keyword(s):  
Reinforced Concrete ◽  
Ultimate Load ◽  
Constant Load ◽  
Reinforced Concrete Beams ◽  
Rc Beams ◽  
Flexural Performance ◽  
Frp Composite ◽  
Steel Bars ◽  
Ocean Environment ◽  
Frp Bars

AbstractIn this paper, the flexural performance of fiber-reinforced polymer (FRP) bars reinforced concrete (RC) beams after conditioning in a simulated seawater wet-dry cycling environment for 6, 9 and 12 months is experimentally investigated. Two types of FRP bars, i.e. basalt FRP (BFRP) bars and steel-FRP composite bars (SFCBs), are adopted. Steel bars are employed for comparison. During the conditioning, a constant load is coupled to the beams. A total of 24 simply supported beams are tested. In addition, microscopic damage to the conditioned BFRP bars is detected by scanning electron microscopy (SEM). The test results indicated that total corrosion was observed at the surface of the bottom longitudinal steel bars after a maximum exposure of 12 months. However, the degradation of the macro-mechanical properties of the steel bars RC beam was not distinct. The ultimate load of the BFRP bars RC beams after 6 months, 9 months and 12 months was reduced by 22%, 33% and 42%, respectively. The yield load and ultimate load of the SFCBs RC beams were reduced by a maximum of 18% and 38%, respectively. The SEM observations revealed that there were distinct damages at the outer layer of the BFRP bars after 12-month conditioning.

scholarly journals Investigation on Flexural Performance of RC Beams Flexurally Strengthened by Side-bonded CFRP Laminates

2012 ◽  
Vol 6 (1) ◽  
pp. 26-32 ◽  
Author(s):  
Guibing Li ◽  
Yugang Guo ◽  
Xiaoyan Sun
Keyword(s):  
Ultimate Load ◽  
Crack Pattern ◽  
Flexural Behavior ◽  
Rc Beam ◽  
Rc Beams ◽  
Load Bearing Capacity ◽  
Cfrp Laminates ◽  
Flexural Performance ◽  
Externally Bonded ◽  
The Difference

It is an effective way to improve the flexural behavior of reinforced concrete (RC) members by externally bonded carbon fiber reinforcement polymer (CFRP) laminates on the soffit of the members. However, there is little investigation on flexural performance of RC beam flexurally strengthened by side-bonded FRP laminates. To investigate the flexural behavior of RC beams side-bonded CFRP laminates and the difference of RC beams strengthened by soffit-bonded and side-bonded CFRP laminates, a total of 8 CFRP-strengthened beams and 1 control beam were tested. The experimental results show that: 1) the first crack loads of RC beams strengthened by side-bonded CFRP laminates are much higher than that of RC beams strengthened by soffit-bonded CFRP laminates. The first crack loads of side-bonded CFRP laminates beams improved significantly; 2) Side-bonded and soffit-bonded CFRP laminates have almost the same effect on the flexural stiffness of RC beams strengthened with same quantity of CFRP laminates before tension rebar yielding. However, side-bonded CFRP laminates can affect crack width and crack pattern of the strengthened beams, and the pre-crack stage of RC beam by sidebonded CFRP laminates extended remarkably. 3) different to soffit-bonded CFRP laminates RC beams, side-bonded CFRP laminates cannot improve the first yielding and the ultimate load bearing capacity of RC beams.

EFFECTIVENESS OF FRCM SYSTEM IN STRENGTHENING RC BEAMS IN SHEAR USING HYBRID NSE/EB TECHNIQUE

2018 ◽  
Vol 5 (1) ◽  
Author(s):  
Usama Ebead ◽  
Tadesse Wakjira
Keyword(s):  
Ultimate Load ◽  
Shear Capacity ◽  
Reference Specimen ◽  
Rc Beams ◽  
Test Results ◽  
Promising Alternative ◽  
Near Surface ◽  
Externally Bonded ◽  
Strengthening Technique ◽  
Fabric Reinforced Cementitious Matrix

This paper presents an experimental study on the efficacy of a recently introduced hybrid “near surface embedded/ externally bonded” NSE/EB fabric reinforced cementitious matrix (FRCM). Seven medium scale RC beams, deficient in shear, were constructed and tested under three-point loading. Six beams were strengthened using hybrid NSE/EB-FRCM technique and one beam was left un-strengthened as a reference. Two main test variables were considered; viz., strengthening configuration: full versus intermittent strengthening configuration and FRCM type: glass FRCM versus polyparaphenylene benzobisoxazole (PBO). The test results revealed that the hybrid NSE/EB-FRCM strengthening technique is effective in enhancing the shear capacity of the strengthened beams. The strengthened specimens showed an average of 67% higher shear capacity relative to the reference specimen. With regard to the FRCM type, G-FRCM strengthened specimens showed an average of 73% enhancement in the shear capacity, which was 12% higher than the value for PBO-FRCM counterpart. Moreover, the strengthened beams showed higher deflection at the ultimate load than that of the reference specimen. Furthermore, the hybrid NSE/EB-FRCM technique has shown to be a promising alternative to the conventionally used externally bonded FRCM system with the potential to reduce the debonding of FRCM from the concrete substrate.

Experimental Response of RC Beams Strengthened in Shear by FRP Sheets

2013 ◽  
Vol 7 (1) ◽  
pp. 127-135 ◽  
Author(s):  
E. Grande ◽  
M. Imbimbo ◽  
A. Rasulo
Keyword(s):  
Slenderness Ratio ◽  
Shear Capacity ◽  
Rc Beams ◽  
Fiber Reinforced Plastic ◽  
Frp Composites ◽  
Reinforced Plastic ◽  
Externally Bonded ◽  
Experimental Response ◽  
Transverse Steel ◽  
Cracking Pattern

The paper discusses the results of an experimental investigation carried out on reinforced concrete (RC) beams strengthened in shear by externally bonded fiber reinforced plastic (FRP) sheets. The study is devoted to analyze the role that the transverse steel reinforcement and the beam slenderness ratio could play on the resistant mechanism of RC beams strengthened in shear by FRP composites. The results are summarized and analyzed in detail in the paper in terms of shear capacity, cracking pattern and shear resisting contribution of FRP.

scholarly journals Leisure Time Sports Activities and Life Satisfaction: Deeper Insights Based on a Representative Survey from Germany

2020 ◽  
Author(s):  
Michael Mutz ◽  
Anne K. Reimers ◽  
Yolanda Demetriou
Keyword(s):  
Life Satisfaction ◽  
Large Scale ◽  
Leisure Time ◽  
Organizational Context ◽  
Experimental Studies ◽  
Well Being ◽  
Activity Level ◽  
Leisure Satisfaction ◽  
General Life Satisfaction ◽  
Sports Activities

Abstract Observational and experimental studies show that leisure time sporting activity (LTSA) is associated with higher well-being. However, scholars often seem to assume that 1) LTSA fosters “general” life satisfaction, thereby ignoring effects on domain satisfaction; 2) the effect of LTSA on well-being is linear and independent of a person’s general activity level; 3) the amount of LTSA is more important than the repertoire of LTSA, i.e. the number of different activities; 4) all kinds of LTSA are equal in their effects, irrespective of spatial and organisational context conditions. Using data from the German SALLSA-Study (“Sport, Active Lifestyle and Life Satisfaction”), a large-scale CAWI-Survey (N = 1008) representing the population ≥ 14 years, the paper takes a closer look on these assumptions. Findings demonstrate that LTSA is associated with general life satisfaction and domain-specific satisfaction (concerning relationships, appearance, leisure, work and health), but that the relationship is most pronounced for leisure satisfaction. Associations of sport with life satisfaction, leisure satisfaction and subjective health are non-linear, approaching an injection point from which on additional LTSA is no longer beneficial. Moreover, findings lend support to the notion that diversity in LTSA matters, as individuals with higher variation in sports activities are more satisfied. Finally, results with regard to spatial and organizational context suggest that outdoor sports and club-organized sports have additional benefits.

scholarly journals Why does the spread of COVID-19 vary greatly in different countries? Revealing the efficacy of face masks in epidemic prevention

2021 ◽  
Vol 149 ◽  
Author(s):  
Jincheng Wei ◽  
Shurui Guo ◽  
Enshen Long ◽  
Li Zhang ◽  
Bizhen Shu ◽  
...  
Keyword(s):  
Social Isolation ◽  
Large Scale ◽  
Experimental Studies ◽  
Weighted Average ◽  
Filtration Efficiency ◽  
Volume Distribution ◽  
Particle Sizes ◽  
Economic Activities ◽  
Protection Measure ◽  
Source Of Infection

Abstract The severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) is highly contagious, and the coronavirus disease 2019 (COVID-19) pandemic caused by it has forced many countries to adopt ‘lockdown’ measures to prevent the spread of the epidemic through social isolation of citizens. Some countries proposed universal mask wearing as a protection measure of public health to strengthen national prevention efforts and to limit the wider spread of the epidemic. In order to reveal the epidemic prevention efficacy of masks, this paper systematically evaluates the experimental studies of various masks and filter materials, summarises the general characteristics of the filtration efficiency of isolation masks with particle size, and reveals the actual efficacy of masks by combining the volume distribution characteristics of human exhaled droplets with different particle sizes and the SARS-CoV-2 virus load of nasopharynx and throat swabs from patients. The existing measured data show that the filtration efficiency of all kinds of masks for large particles and extra-large droplets is close to 100%. From the perspective of filtering the total number of pathogens discharged in the environment and protecting vulnerable individuals from breathing live viruses, the mask has a higher protective effect. If considering the weighted average filtration efficiency with different particle sizes, the filtration efficiencies of the N95 mask and the ordinary mask are 99.4% and 98.5%, respectively. The mask can avoid releasing active viruses to the environment from the source of infection, thus maximising the protection of vulnerable individuals by reducing the probability of inhaling a virus. Therefore, if the whole society strictly implements the policy of publicly wearing masks, the risk of large-scale spread of the epidemic can be greatly reduced. Compared with the overall cost of social isolation, limited personal freedoms and forced suspension of economic activities, the inconvenience for citizens caused by wearing masks is perfectly acceptable.

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