Experiment Studies On The Shear Performance Of Sea Sand Concrete Beam With BFRP Tendons

With the rapid development of Chinese economy and increasing expansion of various constructions, river sand is nearly exhausted because of its huge usage on concrete construction, so exploring the natural resource of sea sand becomes an inevitable tendency, which is also beneficial on environmental protection and economic effects. However, there are high concentration of chloride ion in sea sand, and without sea-sand washing, it may easily corrode steel in concrete, damage the durability of concrete and lead to the phenomenon called "Sea sand house". Scholars studied on the durability of sea sand concrete at home and abroad, and methods of using sea sand on construction were put forward, such as fading, rust and corrosion inhibiting, electrochemical protection and so on. Basalt fiber reinforced rebar (BFRP rebar) not only has the property of high strength, but also resistant corrosion, especially insensitive to chlorine ion. It can significantly improve the corrosion resistance of concrete materials for BFRP rebar directly applying to sea sand concrete structures, which may greatly broke the limitation of using sea sand as the aggregate of concrete directly.Research has been mainly focused on the flexural performance of FRP reinforced concrete components, but less on shear. Studies showed that the bonding force with FRP rebar and concrete was nonlinear along the direction of longitudinal bars and less than that with steel rebar and concrete. The elastic modulus of FRP rebar was relatively small. The deflection and cracks of FRP reinforced concrete beam developed faster than that of reinforced concrete. The bending damage types of the FRP reinforced concrete beam can be divided into rare reinforced, under-reinforced and over reinforced damage. The influencing factors on the shear capacity of FRP reinforced beam were including concrete strength, longitudinal reinforcement ratio and shear span ratio. The design specifications of FRP reinforced concrete structures were established in United States, Canada, Japan and other countries, and lots of calculated formulas on shear capability of FRP reinforced concrete beams without stirrups were created, which were divided into two categories:the first was corrected based on the theory of reinforced concrete members, the second was based on the pressure field theory.This paper studies on the shear performance of the sea sand concrete beam with BFRP reinforced sea sand concrete specimens, and two groups of experiment on BFRP reinforced sea sand concrete beams were carried out, including10beams without Stirrups and6beams with Stirrups. By observing the cracks develop on the beams in the process of experiment, recording the crack widths and collecting the strain, deflection and load of specimens via the computer, the main failure pattern of BFRP reinforced sea sand concrete beams was delivered, and the curves of load-deflection relationship were analyzed, as well as the effecting factors, including concrete strength, longitudinal reinforcement, reinforcement ratio, shear span ratio and stirrup ratio, on the shear capacity of BFRP reinforced sea sand concrete beams. Finally, based on the existed design specifications, a revised formula were derived to calculate the shear capacity of BFRP reinforced sea sand concrete beams, which offers good guidance for engineering practice to some extends.