Seismic response of underwater concrete pipes conveying fluid covered with nano-fiber reinforced polymer layer

This research deals with seismic response of underwater fluid-conveying concrete pipes during the earthquake in Kobe. The pipe is reinforced with nano-fiber reinforced polymer (NFRP) layer. The displacement filed of the structure is considered based on the sinusoidal shear deformation theory. Navier-Stokes equation is applied to estimate the force due to the inner fluid. Furthermore, the effect of the outer fluid is taken into consideration as an equivalent force. The governing equations are derived on the basis of energy method and using Hamilton's principle. Differential quadrature method (DQM) and Newmark method are applied to obtain the dynamic deflection of the system. The effect of parameters such as NFRP layer, volume percent and agglomeration of nano-fibers, boundary conditions, inner and outer fluids, thickness to radius and length to thickness ratios on the dynamic deflection of the structure is examined. The results show that with increasing the thickness to radius ratio and volume percent of nano fiber and using NFRP layer, the dynamic deflection decreases while considering the inner and outer fluids and agglomeration effect of nano fiber and increasing the length to thickness ratio, the dynamic deflection of the structure increases.