Seismic pounding of a 14-story reinforced concrete building, Nuevo León, damaged in the 1985 Mexico Earthquake is investigated by means of dynamic finite element analyses and cyclic loading tests of columns specimens. The building consisted of three adjacent units connected with 100-mm wide expansion joints. It was thought that the poundings caused impact lateral forces and frictions that resulted in serious structural damage. This study attempts quantification of the impact lateral load by the following four steps.(1) Two kinds of seismic response finite element analyses of a single unit of the building are conducted with /without simplified contact modeling with joint elements to approximately estimate the overall structural behavior. (2) Cyclic load test of two column specimens that represent a column of the building. One of the specimens is a simple column while the other consists of four pounding units, to which the column contacts during loading. Comparison of the two specimens indicates that the contact induces additional lateral shear force to the column. (3) Repeated cyclic responses of the two specimens are computed by static finite element analyses. The contact and friction behaviors are classified into normal and shear components to develop a constitutive model to be implemented into the two-node joint element. (4) A finite element model of two partial building units connected with the two-node joint elements is subjected to seismic response analysis. The analysis result indicates that the pounding causes an impact load equivalent to 0.9% of the total weight of a building unit.

Drop-weight tests and static loading tests of RC frames made of polypropylene fiber-reinforced concrete are conducted to observe shock resistance performance and residual ductility. Experimental variables are fiber content and mass of the drop weight. In the impact test, the maximum drifts of the specimens are proportional to the mass of the drop weight although several collisions occur due to rebounding and the maximum acceleration is not always increased as the mass increases. In a static loading test, the initial stiffness is improved and crack lengths in the hinge areas of the columns are reduced by mixing the polypropylene fibers.