Study On Temperature Effect Of Pultruded GFRP Bridge Deck

Pultruded Glass Fiber Reinforced Polymer(GFRP)is more and more widely used in bridge engineering,from GFRP plate,GFRP beam to GFRP cable,GFRP guardrail,GFRP profile is gradually replacing the traditional engineering materials.GFRP profiles have the advantages of light weight and high strength,but the temperature effect of GFRP profiles has been one of the hot research topics.Some studies have shown that GFRP profiles have obvious performance degradation at high temperature.Therefore,it is the basis of engineering design to clarify the temperature effect of GFRP composite structure.The main research contents of this paper are as follows:(1)Referring to the existing GFRP or GFRP composite structure bridge deck system at home and abroad,the design of different span and parameters of the full GFRP bridge deck,GFRp-steel composite bridge deck and GFRP-concrete composite bridge deck,through the heat conduction analysis and applicability,economic and other factors,GFRP-concrete composite bridge deck has certain advantage.(2)ECT specimens were used to study the high temperature fracture properties of pultruded GFRP profiles under different temperatures and different layings,and the failure modes and laws of high temperature fracture were analyzed and discussed.The temperature degradation function curve of GFRP was obtained by the hyperbolic tangent function fitting.In the middle period of the curve,the downward trend was increasing,and the slope was approaching zero at the end of the curve,which indicated that the material degradation was serious and the residual strength was small after the glass transformation temperature.(3)The representative value of Xi ’an air temperature and the change model of daily air temperature and solar radiation were calculated.Based on the actual temperature field,large-scale thermodynamic coupling numerical calculation was carried out to simulate the hourly three-dimensional temperature distribution of GFRP-concrete composite bridge decks under different structural parameters.The simulated vertical temperature gradient curves of GFRP-concrete composite bridge decks are compared with the specifications of steel-concrete composite beams in China and the United Kingdom.The results show that the time for GFRP to reach the maximum temperature in composite bridge decks is later than that of concrete,and the overall vertical temperature gradient curve is approximately three-stage.The temperature self-stress of concrete mainly concentrates on the contact surface with GFRP,and the maximum temperature self-stress of GFRP appears outside the rounded corner.Compared with steel-concrete composite beams,the temperature gradient of GFRP-concrete composite bridge decks is mainly concentrated in the upper part,including the concrete roof,GFRP wings and fillet,which should be taken into consideration in temperature calculation.(4)Combined with the temperature field simulation method of composite bridge deck and the performance degradation law of tensioned GFRP profiles obtained by high temperature tensile test,the performance degradation of tensioned GFRP-concrete composite bridge deck is analyzed at the highest ambient temperature.It is concluded that GFRP-concrete composite bridge deck is suitable for most cases except extreme temperature(such as fire).Its performance degradation at high temperatures is within the safe range.