Abstract: This paper presents model scale tests for 1:50 geometrical scale laboratory modeling for the Texas Tech University (TTU) test building in a gust wind tunnel. This tunnel is able to add low frequency turbulence components for generation of large-scale turbulent flows by the conventional passive simulation technique or a technique combining active and passive turbulence generation devices. This paper mainly studies the effects of the turbulence integral length scale and turbulence intensity on wind-induced pressures on the flat roof of TTU full scale building. The results imply that the turbulence intensity has significant influence on the mean wind pressure coefficients at the leading edge of the flat roof under the separation bubble and in the corner zone for the conical vortex flow regime. Meanwhile, the turbulence intensity plays a predominant role in producing the fluctuation and peak pressure at the leading edge or in the corner area. On the other hand, the turbulence integral length scale has no noticeable influence on the mean wind pressure coefficients at the leading edge or in the corner zone. However, the turbulence integral scale length plays a slightly significant role in producing the fluctuation and peak pressure at the leading edge or in the corner zone.