15 research outputs found
Bond performance of CFRP strengthened steel members subjected to axial compression
No full textThis paper focuses on the use of externally bonded Carbon Fiber Reinforced Polymer (CFRP) materials to strengthen steel plates subjected to compression. A fully slender steel section was selected in this test programme. CFRP strengthened steel plates and non strengthened plates were tested to fail under compressive load. The middle part of the strut was strengthened using CFRP sheet. The length of the strengthened zone was varied. Eight specimens were tested in this test programme. The test results showed a significant strength gain of 47% and delaying of lateral torsional buckling failure mode of strengthened members. This study confirms that there is great potential to increase the short term performance of CFRP strengthened steel structure under axial compression
Experimental and numerical investigation of the behaviour of CFRP strengthened CHS beams subjected to bending
No full textThis paper presents the results of an experimental and numerical program to investigate the circular hollow section (CHS) beams, strengthened using Carbon Fibre Reinforced Polymer (CFRP) sheets. The circular hollow shaped steel beams bonded with different CFRP layer orientations were tested under four-point bending. The mid-span deflection, service load and failure load were recorded. The LHL (where L, first inner longitudinal layer, H, second hoop layer and L, third outer longitudinal layer) and LLH (where L, first inner longitudinal layer, L, second longitudinal layer and H, third outer hoop layer) layer oriented strengthened beams perform slightly better than HHL (where H, first inner hoop layer, H, second hoop layer and L, third outer longitudinal layer) layer oriented strengthened beams. The LHL and LLH layer oriented treated beams showed very similar structural behaviour. Numerical analyses were then conducted on the CFRP strengthened steel CHS beams. The validity of the models has been assessed by comparing the failure loads and mid-span deflections. The effects of various parameters such as bond length, section types, tensile modulus of CFRP, adhesive layer thickness and adhesive types have been studied
Durability performance of carbon fibre-reinforced polymer strengthened circular hollow steel members under cold weather
No full textThe use of circular hollow steel members has attracted a great deal of attention during past few years because of having excellent structural properties, aesthetic appearance, corrosion and fire protection capability. However, no one can deny the structural deficiency of such structures due to reduction of strength when they are exposed to severe environmental conditions such as marine environment, cold and hot weather. Hence strengthening and retrofitting of structural steel members is now very imperative. This paper presents the findings of a research program that was conducted to study the bond durability of carbon fibre-reinforced polymer (CFRP) strengthened steel tubular members under cold weather and tested under four-point bending. Six number of CFRP-strengthened specimens and one unstrengthened specimen were considered in this program. The three specimens having sand blasted surface to be strengthened was pre-treated with MBrace primer and other three were remained untreated and then cured under ambient temperature at least four weeks and cold weather (3 C) for three and six months period of time. Quasi-static tests were then performed on beams to failure under four-point bending. The structural response of each specimen was predicted in terms of failure load, mid-span deflection, composite beam behaviour and failure mode. The research outcomes show that the cold weather immersion had an adverse effect on durability of CFRP-strengthened steel structures. Moreover, the epoxy based adhesion promoter was found to enhance the bond durability in plastic range. The analytical models presented in this study were found to be in good agreement in terms of predicting ultimate load and deflection. Finally, design factors are proposed to address the short-terms durability performance under cold weather
Comparative durability study of CFRP strengthened tubular steel members under cold weather
No full textIn strengthening systems, the CFRP (Carbon Fibre Reinforced Polymer) materials typically have excellent resistance against environmental conditions; however, the performance of adhesives between CFRP and steel is generally affected by various environmental conditions such as marine environment, cold and hot weather. This paper presents the comparative durability study of CFRP strengthened tubular steel structures by using two different adhesives such as MBrace saturant and Araldite K630 under four-point bending. The program consisted of testing twelve CFRP strengthened specimens having treated with epoxy based adhesion promoter, untreated surface and one unstrengthened specimen and conditioned under cold weather for 3 and 6 months to determine the environmental durability. The beams were then loaded to failure in quasi-static manner under four-point bending. The structural responses of CFRP strengthened tubular steel beams were compared in terms of failure load, stiffness and modes of failure. The research findings show that the cold weather immersion had adversely affected the durability of CFRP strengthened steel members. Design factor is also proposed to address the short-terms durability performance under cold weather
Właściwości termiczne mieszanki zaprawy ryżowo-łupkowej w budownictwie betonowym i murarskim
No full textRice Husk (RH) is an agricultural waste which is produced in huge amounts from the milling process of paddy rice. Rice Husk Ash (RHA) is a by-product material obtained from the combustion of rice husk. The amorphous silica-rich RHA (84-90 wt%) has a wide range of applications. This research focused on the possibility of utilizing RHA in the process of developing a mortar with low thermal conductivity to enhance the thermal comfort in concrete and masonry buildings. The thermal conductivity of mortar was determined by Lee’s Disc method, and the results were compared to the data for conventional mortar as well as commercial thermal insulation materials. The results indicate a significant reduction in thermal conductivity in the mortar developed with RHAŁuska ryżowa (Rice Husk, RH) jest odpadem rolniczym, który jest produkowany w ogromnych ilościach w procesie mielenia ryżu niełuskanego. Popiół z łuski ryżowej (Ryż Husk Ash – RHA) jest produktem ubocznym uzyskiwanym w procesie spalania łuski ryżowej. Bogaty w krzemionkę amorficzną RHA (84-90 % mas.) ma wiele zastosowań. Badania te skupiały się na możliwości wykorzystania RHA w procesie opracowywania zaprawy o niskiej przewodności cieplnej w celu zwiększenia komfortu cieplnego w budownictwie betonowym i murowym. Przewodność cieplną zaprawy określono metodą Lee's Disc, a wyniki porównano z danymi dla zaprawy konwencjonalnej oraz handlowych materiałów termoizolacyjnych. Wyniki wskazują na znaczne obniżenie przewodności cieplnej w zaprawie opracowanej przy użyciu RHA
Właściwości termiczne mieszanki zaprawy ryżowo-łupkowej w budownictwie betonowym i murarskim
No full textRice Husk (RH) is an agricultural waste which is produced in huge amounts from the milling process of paddy rice. Rice Husk Ash (RHA) is a by-product material obtained from the combustion of rice husk. The amorphous silica-rich RHA (84-90 wt%) has a wide range of applications. This research focused on the possibility of utilizing RHA in the process of developing a mortar with low thermal conductivity to enhance the thermal comfort in concrete and masonry buildings. The thermal conductivity of mortar was determined by Lee’s Disc method, and the results were compared to the data for conventional mortar as well as commercial thermal insulation materials. The results indicate a significant reduction in thermal conductivity in the mortar developed with RHAŁuska ryżowa (Rice Husk, RH) jest odpadem rolniczym, który jest produkowany w ogromnych ilościach w procesie mielenia ryżu niełuskanego. Popiół z łuski ryżowej (Ryż Husk Ash – RHA) jest produktem ubocznym uzyskiwanym w procesie spalania łuski ryżowej. Bogaty w krzemionkę amorficzną RHA (84-90 % mas.) ma wiele zastosowań. Badania te skupiały się na możliwości wykorzystania RHA w procesie opracowywania zaprawy o niskiej przewodności cieplnej w celu zwiększenia komfortu cieplnego w budownictwie betonowym i murowym. Przewodność cieplną zaprawy określono metodą Lee's Disc, a wyniki porównano z danymi dla zaprawy konwencjonalnej oraz handlowych materiałów termoizolacyjnych. Wyniki wskazują na znaczne obniżenie przewodności cieplnej w zaprawie opracowanej przy użyciu RHA
Development of sustainable mortar using waste rice husk ash from rice mill plant: Physical and thermal properties
No full text
Finite Element Modelling on Flexural Performance of CFRP Strengthened Reinforced Concrete Curved Beams
No full textA numerical model was developed to investigate
the flexural performance of Carbon Fibre Reinforced Polymer
(CFRP) strengthened concrete curved beams subjected to outof-
plane bending. In this study, near surface mounted (NSM)
technique has been used to strengthen the curved beams due to
easy of application in curved beams subjected to out-of-plane
bending. A commercially available finite element analysis
software was used to simulate a numerical model and a nonlinear
analysis was carried out. Alternative bonding
arrangements were considered. The results indicate the highest
strength performance in the curved beams with CFRP strip
bonded in the radial direction of the beams. Further, it was
revealed that the CFRP thickness, Elastic Modulus of CFRP,
Concrete Grade, and the beam curvature affect the strength
enhancement
Effects of surface roughness and bond enhancing techniques on flexural performance of CFRP/concrete composites
No full text
