Our lab has focused on new material development for structural members together with visualization of internal forces in complicated structures. Strut-and-tie models serve us basic concepts to understand force flows in such reinforced concrete structures at ultimate such as bar development and anchorage, shear and even deformability after yielding. Shear strength of steel plate concrete composite walls, precast Twalls, beam-to-columns joints have been investigated. Cyclic behaviors of Koreantraditional wooden frames under earthquake, structural stability of a stone pagoda, and arches in tumulus have been investigated for the understanding of structural aspects. The reinforcement method for fractured granite rock members for reconstruction of stone pagoda. Structural behaviors of arches are understood by graphic statics. Textile reinforced concrete with hybrid fiber concrete requires multi-scale mechanics. For the insulation performance of a new fire resistant mortar mixed with microspheres on the surface of concrete structures, our labinvestigates the thermal properties of the cement mortars.