Effects of Thermal Loads on Concrete Cover of Fiber-Reinforced Polymer Reinforced Elements: Theoretical and Experimental Analysis

2001 ◽  
Vol 98 (4) ◽  
Keyword(s):  
Experimental Analysis ◽  
Concrete Cover ◽  
Fiber Reinforced Polymer ◽  
Thermal Loads ◽  
Fiber Reinforced ◽  
Reinforced Polymer

Thermal effect on fiber reinforced polymer reinforced concrete slabs

2008 ◽  
Vol 35 (3) ◽  
pp. 312-320 ◽  
Author(s):  
A. Zaidi ◽  
R. Masmoudi
Keyword(s):  
Thermal Effect ◽  
Concrete Cover ◽  
Fiber Reinforced Polymer ◽  
Concrete Slabs ◽  
Fiber Reinforced ◽  
Reinforced Concrete Slabs ◽  
Reinforced Polymer ◽  
Frp Bar ◽  
Frp Bars ◽  
Concrete Interface

The difference between the transverse coefficients of thermal expansion of fiber reinforced polymer (FRP) bars and concrete generates radial pressure at the FRP bar – concrete interface, which induces tensile stresses within the concrete under temperature increase and, eventually, failure of the concrete cover if the confining action of concrete is insufficient. This paper presents the results of an experimental study to investigate the thermal effect on the behaviour of FRP bars and concrete cover, using concrete slab specimens reinforced with glass FRP bars and subjected to thermal loading from –30 to +80 °C. The experimental results show that failure of concrete cover was produced at temperatures varying between +50 and +60 °C for slabs having a ratio of concrete cover thickness to FRP bar diameter (c/db) less than or equal to 1.4. A ratio of c/db greater than or equal to 1.6 seems to be sufficient to avoid splitting failure of concrete cover for concrete slabs subjected to high temperatures up to +80 °C. Also, the first cracks appear in concrete at the FRP bar – concrete interface at temperatures around +40 °C. Comparison between experimental and analytical results in terms of thermal loads and thermal strains is presented.

scholarly journals Experimental Analysis of Continuous Beams Made of Self-Compacting Concrete (Scc) Strengthened with Fiber Reinforced Polymer (Frp) Materials

2021 ◽  
Vol 11 (9) ◽  
pp. 4032
Author(s):  
Žarko Petrović ◽  
Bojan Milošević ◽  
Slobodan Ranković ◽  
Biljana Mladenović ◽  
Dragan Zlatkov ◽  
...  
Keyword(s):  
Experimental Analysis ◽  
Failure Modes ◽  
Fiber Reinforced Polymer ◽  
Flexural Behavior ◽  
Engineering Practice ◽  
Fiber Reinforced ◽  
Self Compacting Concrete ◽  
Near Surface ◽  
Reinforced Polymer ◽  
Continuous Beams

Strengthening of concrete structures is applied as a solution for various deterioration problems in civil engineering practice. This also refers to the structures made of self-compacting concrete (SCC), which is increasingly in use, but there is a lack of research in this field. This paper presents an experimental analysis of flexural behavior of reinforced concrete (RC) continuous beams made of SCC, strengthened with fiber reinforced polymer (FRP) materials (glass (GFRP) and carbon (CFRP) bars, CFRP laminates), by the use of near surface mounted (NSM) and externally bonded (EB) methods. Six two-span continuous beams of a total length of 3200 mm, with the span between supports of 1500 mm and 120/200 mm cross section, were subjected to short-term load and tested. The displacements of beams and the strains in concrete, steel reinforcement, FRP bars and tapes were recorded until failure under a monotonically increasing load. The ultimate load capacities of the strengthened beams were enhanced by 22% to 82% compared to the unstrengthened control beam. The ductility of beams strengthened with GFRP bars was satisfactory, while the ductility of beams strengthened with CFRP bars and tapes was very small, so the failure modes of these beams were brittle.

Numerical simulation of one-way concrete slabs reinforced with glass fiber reinforced polymer bars under service temperatures

2018 ◽  
Vol 45 (10) ◽  
pp. 878-888
Author(s):  
Samia Lardjane ◽  
Hizia Bellakehal ◽  
Ali Zaidi ◽  
Radhouane Masmoudi
Keyword(s):  
Numerical Model ◽  
Concrete Cover ◽  
Fiber Reinforced Polymer ◽  
Concrete Slabs ◽  
Thermal Loads ◽  
Gfrp Bars ◽  
Reinforced Polymer ◽  
Splitting Failure ◽  
Frp Bar ◽  
Concrete Interface

The thermal incompatibility between fiber reinforced polymer (FRP) bars and concrete may cause splitting cracks within the concrete and, eventually, the deterioration of the bond between the FRP bar and the concrete. This paper presents a numerical study using ADINA finite elements software to investigate the thermal behavior of actual one-way concrete slabs reinforced with glass FRP (GFRP) bars varying the ratio of concrete cover thickness to FRP bar diameter (c/db) from 1.3 to 2.8. Slabs are submitted to temperature variations varied from −50 to 60 °C. The main results prove that first radial cracks occur in concrete, at the FRP bar – concrete interface, at thermal loads (ΔTcr) varied between 15 °C and 30 °C. While, the circumferential cracks appear within concrete, at FRP bar – concrete interface, at ΔTcr varied between −15 °C and −35 °C depending of the ratio c/db (1.3 to 2.8) and the tensile strength of concrete fct (1.9 to 2.9 MPa). These numerical thermal loading values are relatively in good agreement with those predicted from the analytical model. The numerical model shows that there is no failure of the concrete cover for low temperatures for slabs having c/db = 1.3 to 2.8 and fct = 1.9 to 2.9 MPa. Nevertheless, for high temperatures, the splitting failure of concrete cover is produced at thermal loads ΔTsp′ varied from 30 °C to 59 °C. While, for concrete situated between GFRP bars, the splitting failure occurred at thermal loads ΔTsp′ equal to 46 °C. Thermal stresses and strains, and also cracking thermal loads predicted from the numerical model are compared with those obtained from analytical models and experimental tests.

ANCHORAGE CHARACTERISTICS OF NON-METALLIC REINFORCEMENT FOR CONCRETE

2011 ◽  
Vol 3 (2) ◽  
pp. 72-78 ◽  
Author(s):  
Mantas Atutis ◽  
Juozas Valivonis
Keyword(s):  
Experimental Tests ◽  
Concrete Cover ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Anchorage Length ◽  
Reinforcing Bar ◽  
Reinforced Polymer ◽  
Metallic Reinforcement ◽  
Bar Diameter

This article analyzes the basic problems of the anchorage of non-metallic reinforcement for concrete and reviews calculation methods of anchorage length using ACI, STR, JSCE and fib Model Code 2010. The paper presents a comparison of experimental (Benmokrane et al. 2003) and theoretical results and studies the major types of experimental tests to determine the bond strength of FRP reinforcing bars. The anchorage length of continuous fiber reinforcement (non-metallic reinforcement bars) is calculated using diff erent expressions proposed in codes and recommendations, thus providing with particular results. The article also shows how the anchorage length of a reinforcing bar is influenced by mechanical properties of reinforcement and concrete, concrete cover and the diameter of the reinforcing bar. Experimental results are compared with theoretically obtained values referring to codes and recommendations. A scatter of results is 3.67-10.18. It was found, that the anchorage length of the carbon fiber reinforced polymer (CFRP) bar calculated by ACI, STR, JSCE and MC increases in the number of times an increase in bar diameter. It has been stated, that anchorage length decreases by 1,44 and 1,71 when the compression strength of concrete increases by 2 and 4. Theoretical calculations have revealed that depending on a bar diameter, in order to minimize the anchorage length of non – metallic reinforcement, the use of the concrete cover higher than 3 db is not feasible. Moreover, when using conventional steel for concrete reinforcement, anchorage length is 3 times less than that of a concrete member with carbon fiber reinforced polymer (CFRP) reinforcement and 2 times less than using basalt fiber reinforced polymer (BFRP) reinforcement. Calculation methodology for the anchorage length of a steel reinforcing bar can be used for calculating the anchorage length of non-metallic reinforcement. However, individual coefficients of diff erent FRP reinforcement must be applied to determine environmental factors and temperature of mechanical properties of non-metallic reinforcement. The values of coefficients must be determined conducting experimental tests.

Experimental investigation on axial compressive behavior of fiber reinforced polymer-reinforced concrete columns confined with external fiber reinforced polymer jackets

2021 ◽  
pp. 136943322110262
Author(s):  
Chuanxiang Chen ◽  
Zhenyu Wang ◽  
Wei Zhou
Keyword(s):  
Reinforced Concrete ◽  
Concrete Columns ◽  
Concrete Cover ◽  
Fiber Reinforced Polymer ◽  
Test Results ◽  
Fiber Reinforced ◽  
Reinforced Concrete Columns ◽  
Reinforced Polymer ◽  
Frp Wrapping ◽  
Frp Bars

An innovative glass fiber reinforced polymer (GFRP) closed-type winding (GFRP-CW) tie was developed to eliminate the bond slip failure and make full use of the tensile strength of ties compared with conventional pultruded fiber reinforced polymer (FRP) rod ties. Although better confinement effect of GFRP-CW ties, however after spalling of concrete cover, the compressive longitudinal FRP bars in the plastic hinge regions of columns are most likely to crush or buckle. External FRP jackets can effectively restraint damage to concrete cover. Against this background, a novel FRP-reinforced concrete column confined with external FRP jackets and the internal GFRP-CW ties were proposed to prevent the FRP bars from premature buckling or crushing. In this article, twelve square new columns were constructed and tested to characterize the axial compressive behavior. The test parameters included FRP wrapping type (GFRP or carbon fiber reinforced polymer (CFRP)), FRP wrapping layers, and spacing of ties. Test results confirmed that FRP-reinforced concrete columns with external FRP jackets had significantly larger ductile behavior and exhibited higher load-carrying capacity than their counterparts FRP-reinforced concrete columns due to the contribution of longitudinal GFRP bars and the concrete cover. The test results also suggested reasonable spacing of ties and layers of GFRP jackets for an expected moderate confinement behavior.

Sign in / Sign up

Export Citation Format

Share Document