Trial Design And Research On Concrete Filled FRP Tube Stress Ribbon Arch Bridge

This paper focus on a trial design of a concrete filled FRP tube stress ribbon arch bridge (CFFT-SRAB) which taken a constructed concrete filled steel tube stress ribbon arch bridge (CFST-SRAB) as background project. It has good economic benefit by using FRP instead of steel to solve the problem of corrosion and prolong the service life of the bridge, enhanced the structural reliability used for a certain period of time and reduces the maintenance cost. Meanwhile, the components of FRP composite bridge can be transported to the site after the installation of prefabricated, that can save a lot of construction time and reduce the impact to the traffic. What is more, FRP has the characteristics of high strength to weight ratios, weighs only 15%-27% with the same volume of steel tubes, using only small machinery can put FRP tubes hoisting in place, thus brought great convenience to construction. In order to understand the mechanical characteristics and calculation methods of CFFT-SRAB, this paper carried out the design calculation, checking calculation and parameter analysis based on this type of bridge and goes further by comparing with the characteristics of CFST-SRAB. The main research results are as follows:(1) Design calculations and analysis on a CFFT-SRAB were carried out with a CFST-SRAB as background project. A FEM of CFFT-SRAB was established to analyze the mechanical behavior during construction stage and completed stage and the results of main components or structures of CFFT-SRAB were checked according to domestic and foreign regulations. The results show that the trial design meets the requirements of mechanical performance on the specification.(2) Compared CFST-SRAB with CFFT-SRAB by construction method, mechanical behavior, economy and dynamic characteristics. The comparison shows that the construction method of CFFT-SRAB is more convenient than CFST-SRAB and internal force of CFFT-SRAB is greatly reduced during the construction stage and service stage; During the construction stage when the stress ribbon completed, the maximum axial force of arch rib of CFFT-SRAB only 59.14% of CFST-SRAB, the tensile force of stress ribbon only 40.91% of CFST-SRAB. During the service stage, the maximum axial force of arch rib of CFFT-SRAB only 69.81% of CFST-SRAB, and the tensile force of stress ribbon only 34.78% of CFST-SRAB.(3) Parameter analysis has been done towards CFFT-SRAB after calculation checking. The calculation results show that the horizontal thrust, axial force of arch foot and tensile force of stress ribbon of CFFT-SRAB present a rapid decrease trend when the rise-span ratio in the range of 0.10-0.15; The internal forces continue to reduce and the decrease trends turn slow when the rise-span ratio in the range of 0.15-0.25;The maximal displacement of arch rib continues to decrease, the maximum displacement of stress ribbon continues to increase and the natural frequencies continue to decrease with the increase of rise-span ratio, while rise-span ratio is less than 0.20, the according first order vertical natural frequency is greater than 3.00 Hz. While the camber angle of main arch rib increased from 20° to 40°, the horizontal thrust and axial force of arch foot, tensile force and maximum vertical displacement of stress ribbon are increasing trend. With the increase of diameter-thick ratio, compression strength, flexural bearing capacity of CFFT are reduced, while first-order vertical natural frequency basically remain unchanged. The 100mm thickness of FRP bridge panel can be used to meet the requirements of the stress of the pedestrian bridge.