Puducherry is a coastal region in India where the growth of Ulva fasciata (Delile) is very abundant on all marine structures. Though the detrimental effect of this macro algae Ulva fasciata is a secondary one, its effect has to ascertain. To know its effect, the basic mechanism by which Ulva fasciata deteriorates concrete structures, M20 grade concrete cubes were casted and kept in the coastal area where there is abundant growth of Ulva fasciata and also laboratory simulation has been carried out. To ascertain the detrimental effect by the macro algae on concrete surface, samples were collected from the concrete cubes kept in the coastal area and also from the laboratory simulated one. The collected samples were analyzed by SEM, EDX and XRD to establish the degree of deterioration done by marine algae on concrete surface. The SEM and EDX results showed that there is a remarkable change in the base materials viz., Ca and Si content and XRD results revealed the absence of Calcium Hydroxide. Both the results confirmed the biodeterioration of concrete by the marine green algae.

The occurrence of wave and wind forces on tension leg platform (TLP) was assumed to be statistically independent but the intensity of wave force is a function of wind velocity because wave is a wind driven force. The focus of this paper is to study the effects of wind velocity on wave force. The contribution of steady and fluctuating wind to the response of the TLP over random wave only was also studied. Pierson Moskowitz wave and Emil Simiu wind spectra are simulated using Monte Carlo simulation. The variable submergence, drag force in Morison equation, tension fluctuation together with coupling between wind and wave contributed to the non-linearity considered in the single degree of freedom equation. The dynamic equation was solved using Newmark-Beta scheme. The statistical and power spectral density functions of the response quantities are reported. It is concluded that wind forces reduce the root mean square (RMS) tension force in the cable and thereby increased the motion responses in intact and a removed tendon TLP. The wind driven force (wave) has higher responses in severe sea states and the contribution of wind effect was suppressed due to hydrodynamic damping. The effect of the wind fluctuation is more pronounced in less severe sea state.Stochastic response of intact and a removed tendon tension leg platform to wave and wind loads