Thesis or Dissertation STRUCTURAL BEHAVIOUR OF COMPOSITE GIRDERS USING HIGH STRENGTH FIBRE REINFORCED CONCRETE AND FIBRE REINFORCED POLYMERS

ISURU SANJAYA KUMARA WIJAYAWARDANE

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指導教員 : 睦好宏史
ABSTRACT ............................................................................................................................... iDEDICATION ......................................................................................................................... ivACKNOWLEDGEMENT ....................................................................................................... vTable of Contents .................................................................................................................... viList of Tables ............................................................................................................................ ixList of Figures ........................................................................................................................... xAbbreviations ......................................................................................................................... xiiiChapter 1: Introduction ........................................................................................................... 11.1 Types of FRP composites used in civil engineering ........................................................ 21.2 Literature review .............................................................................................................. 31.2.1 Use of FRP and UFC for short span pedestrian bridges ........................................... 31.2.2 Influence of elevated temperature on FRP materials ................................................ 51.2.3 Performance FRP composite structures subjected to elevated temperature .............. 71.3 Objectives and scope ........................................................................................................ 91.4 Organization of the dissertation ..................................................................................... 11Chapter 2: Flexural Behaviour of GFRP and UFC Composite Beams Having FRP Bolts as Shear Connectors .............................................................................................................. 132.1 Introduction .................................................................................................................... 132.2 Materials ......................................................................................................................... 132.2.1 GFRP I-beams ......................................................................................................... 132.2.2 UFC ......................................................................................................................... 152.2.3 FRP bolts and epoxy adhesive ................................................................................ 162.3 Test variables and methodology of GFRP and UFC composite beam flexural test ....... 172.4 Results and discussion .................................................................................................... 222.4.1 Comparison of bolt type .......................................................................................... 242.4.2 Comparison of UFC segment gap ........................................................................... 252.4.3 Comparison of bolt spacing ..................................................................................... 262.4.4 Comparison of FRP bolt diameter ........................................................................... 272.4.5 Composite behaviour of test specimens .................................................................. 272.5 Concluding remarks ....................................................................................................... 29Chapter 3: Influence of Elevated Temperature on the Mechanical Properties of Materials Used in FRP and UFC Composite Beams ........................................................................... 303.1 Details of test specimens and methodology ................................................................... 303.1.1 Glass transition temperature test on GFRP, HFRP, FRP bolts and epoxy adhesive323.1.2 Coefficient of thermal expansion test on GFRP, HFRP and UFC .......................... 323.1.3 Tensile and compression tests on GFRP and HFRP coupons ................................. 333.1.4 Compression test on UFC ....................................................................................... 353.1.5 Tensile, compression and shear tests on FRP bolts ................................................. 363.1.6 Shear test on epoxy adhesive .................................................................................. 373.2 Material test results and discussion ................................................................................ 383.2.1 Results of glass transition temperature tests ........................................................... 383.2.2 Results of coefficient of thermal expansion tests .................................................... 393.2.3 Results of tensile tests ............................................................................................. 393.2.4 Results of compression tests ................................................................................... 423.2.5 Results of shear tests ............................................................................................... 443.3 Concluding remarks ....................................................................................................... 45Chapter 4: Flexural Behaviour of FRP I-beams and FRP-UFC Composite Beams Subjected to Elevated Temperature .................................................................................... 464.1 Introduction .................................................................................................................... 464.2 Test variables and methodology ..................................................................................... 464.3 Results and discussion .................................................................................................... 504.4 Concluding remarks ....................................................................................................... 60Chapter 5: Fibre Model Analysis ......................................................................................... 625.1 Calculation procedure in the fibre model analysis ......................................................... 625.2 Fibre Model Analysis of GFRP I-beams and GFRP-UFC Beams with a Small Temperature Gradient .......................................................................................................... 665.3 Fibre Model Analysis of GFRP and UFC Beams with a Large Temperature Gradient . 695.4 Concluding remarks ....................................................................................................... 71Chapter 6: Flexural Performance of Short span Pedestrian Bridge Consisting of GFRP and UFC Composite Beams .................................................................................................. 736.1 Introduction .................................................................................................................... 736.2 Experiment details of the static loading tests on the short span bridge .......................... 766.3 Results and discussion .................................................................................................... 776.4 Concluding remarks ....................................................................................................... 80Chapter 7: Conclusions and recommendations for future studies ................................... 817.1 Flexural Behaviour of GFRP and UFC Composite Beams Having FRP Bolts as ShearConnectors ............................................................................................................................ 817.2 Influence of Elevated Temperature on the Mechanical Properties of Materials Used in FRP and UFC composite beams ........................................................................................... 817.3 Flexural Behaviour of FRP I-beams and FRP-UFC Composite Beams Subjected to Elevated Temperature .......................................................................................................... 827.4 Fibre Model Analysis ..................................................................................................... 837.5 Flexural Performance of Short span Pedestrian Bridge Consisting of GFRP and UFC Composite Beams ................................................................................................................. 847.6 Recommendations for future studies .............................................................................. 84PUBLICATIONS ................................................................................................................... 86REFERENCES ....................................................................................................................... 88Annexure: A ............................................................................................................................ 92
Fibre reinforced polymer (FRP) materials are being used for construction of the civil engineering structures because of their outstanding properties compared to the conventional construction materials. One of the main applications of the FRP is short span bridge construction. The superior features of the FRP include high tensile strength, high corrosion resistance, low weight, high fatigue resistance, etc. Furthermore, the use of the FRP reduces the life-cycle cost of a structure and the amount of carbon dioxide emission as compared to the prestressed concrete or steel bridges. The high durability of the FRP makes these materials suitable for short span bridges those are exposed to severe environmental conditions.In most of the FRP bridges, steel bolts are used to connect the members together. Therefore, maintenance and repairing of the steel connections need to be carried out time to time. At the first stage of this study, glass fibre reinforced polymer (GFRP) and ultra-high strength fibre reinforced concrete (UFC) composite beams were developed to address that shortcoming. Noncorroding FRP bolts were used instead of the steel bolts and the flexural behaviour of the GFRP and UFC composite beams was studied. The GFRP and UFC composite beams were made by connecting precast UFC segments to the GFRP I-beam top flange using the FRP bolts and the epoxy adhesive. The four-point flexural tests were conducted on the large-scale GFRP and UFC composite beams by changing the FRP bolt diameter, bolt spacing and FRP bolt type in order to find out the suitable FRP bolt parameters. The experiment revealed that the FRP bolts can be used in the GFRP and UFC composite beams, instead of the steel bolts. Both the flexural capacity and the stiffness of the composite beams containing the steel bolts and the FRP bolts were similar. There was full composite behaviour until beam failure in the GFRP and UFC beams having FRP bolts and in the GFRP and UFC composite beams having steel bolts.As well as the GFRP, the hybrid FRP (HFRP) also can be used for making the FRP and UFC composite beams. The GFRP consisted of glass fibres whereas the HFRP used in this study consisted of carbon and glass fibres. In both FRP types, the fibres were bonded together with the vinylester resin matrix. The polymer resin matrices contained in the GFRP, HFRP, FRP bolts, and the epoxy adhesive are susceptible to degrade their mechanical properties at glass transition temperature (Tg). Therefore, the flexural behaviour of the GFRP or HFRP (GFRP/HFRP) and UFC composite beams can be affected by elevated temperature. The temperature of the concrete bridge deck can reach 60°C or more when they are exposed to extremely hot climates or when they are located in hot industrial environments. Therefore, the second stage of this study was carried out to identify the influence of elevated temperature on the mechanical properties of the materials used in the GFRP/HFRP and UFC composite beams and to investigate the flexural behaviour of the GFRP/HFRP and UFC composite beams at elevated temperature.Experiments were conducted at temperatures between 20°C and 90°C to check the temperature dependence of the materials used in the GFRP/HFRP and UFC composite beams. The experiment results emphasized that the glass transition temperatures of the materials used in the GFRP/HFRP and UFC composite beams are in between 50°C and 60°C. The compressive strength of the GFRP, HFRP, and the FRP bolts is significantly affected by the glass transition. The tensile strength of the GFRP and the HFRP is greatly affected by the Tg of the vinylester resin whereas in the FRP bolts, the tensile strength is not significantly affected by the Tg. The compressive strength of the UFC also independent of temperature within 20°C and 90°C. The coefficients of thermal expansion of all the materials used in the GFRP/HFRP and UFC composite beams are constant at all temperatures between 20°C and 85°C. There is no influence on the longitudinal expansion rates of the materials by their glass transition temperatures. Shear strength of the FRP bolts rapidly reduced at the temperatures beyond 60°C whereas the shear capacity of the epoxy adhesive reduced with temperature regardless the Tg of the epoxy adhesive.The flexural behaviour of the GFRP I-beams, GFRP-UFC composite beams, and the HFRPUFC composite beams under room and elevated temperatures (between 20°C and 90°C) was studied. Prior to loading, all the beams except the beams at 20°C were heated up to the test temperature and kept constant at the same temperature for one hour. Similar to the material test results, the beam test results revealed that the flexural behaviour of the GFRP I-beams is influenced by the glass transition temperature of the vinylester resin. Both the flexural capacity and the stiffness of the GFRP I-beams are decreased at elevated temperature beyond the Tg of the vinylester resin. Use of the UFC segments significantly improves the ultimate flexural capacity and the stiffness of the GFRP I-beams at temperatures ranged from 20°C to 90°C. This is because the UFC segments can prevent premature delamination and kink failure of the GFRP I-beam compression flange. As a result, the tensile strength of the GFRP I-beam can be effectively utilized. It was confirmed that the bi-material bending effect in the GFRP/HFRP and UFC composite beams is negligible due to the close thermal expansion rates of the GFRP, HFRP, and the UFC materials. As well as the GFRP I-beams, the GFRP-UFC composite beams and the HFRP-UFC composite beams are affected by elevated temperature and their flexural capacities were decreased as the beam temperature increases. However, more than 85% of the flexural capacity (compared to the flexural capacity at 20°C) of three beam types can be retained when the beam temperature is below 60°C. As the beam temperature increases beyond 60°C, the flexural capacity of these beams severely degraded. Furthermore, in these GFRP/HFRP and UFC composite beams, the failure mode depends on the shear capacity of the FRP bolts at the beam temperature.Flexural behaviour of the GFRP I-beams and the GFRP and UFC composite beams was analysed using fibre model and the analysis results were verified by the experiment results. The fibre model can predict the flexural behaviour of the GFRP I-beams at temperatures between 20°C and 90°C. Regarding the GFRP and UFC composite beams, the fibre model results were be valid up to the slipping of the UFC segments. When there was no slip of the UFC segments, fibre model analysis results were agreed up to the failure of the composite beams. Under the actual circumstances, the GFRP and UFC composite beams may experience a large temperature gradient across beam top to bottom. According to the fibre model analysis, it was found that the stiffness of the GFRP and UFC composite beams, which is related to the main design criterion of the FRP bridges, is not significantly affected by the temperature gradient in the real situations. However, the flexural capacity of the GFRP and UFC composite beams at the slipping of the UFC segments is greatly influenced by the temperature of the beam top.The high corrosion resistant GFRP and UFC composite beams were used as bridge girders to construct a short span pedestrian bridge in Japan. This bridge was constructed in a fishery harbour where corrosion is a major issue. The overall length and the width of the bridge are 6,000 mm and 960 mm, respectively. The static load tests conducted on the bridge confirmed the excellent performance of the GFRP and UFC composite beams.
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