Abstract： Great wave triggered by typhoon may present severe danger to the construction safety of sea-crossing bridge cofferdam. Compared with regular wave, typhoon-induced wave has characteristics of longer periods and greater wave heights, which just coincide with those of focused wave. To better guide the design of the cofferdam’s resistance to the extreme typhoon-induced wave, a wave flume experimental study of the interaction between focused wave and bridge cofferdam is conducted. In the study, the influences of the cofferdam draught, maximum wave amplitude and incident wave angles of focused wave on wave elevation and wave force are discussed. The results show that changes of the cofferdam draught and incident wave angles have little influence on wave elevation. With the cofferdam draught increasing, effective projection areas of transverse wave-propagation directions increase, longitudinal wave force increases largely. Besides, as a result of wave energy attenuation with water depth, uplift force at the bottom decreases. With the increase of wave incident angles, the expansion of effective projection areas causes that the longitudinal wave force increases nonlinearly, while the uplift force at the bottom changes smoothly. When incident wave angles and wave amplitudes are relatively large, there are comparatively remarkable differences between positive and negative amplitude values of the longitudinal and transverse wave force. What’s more, the longitudinal and transverse wave force would present significant asymmetry, resulting in a relatively dangerous construction design if it’s based on symmetrical force. Compared with focused waves of the same wave amplitude, regular wave force is much more dangerous especially with longer period condition. Thus it’s necessary to consider the focused waves as the typhoon- induced wave for the actual sea-crossing bridge engineering.
