9 9. COMPARISON OF LARGE-SCALE (1:2) AND SMALL-SCALE (1:5) MODELS

The performance of large-scale and small-scale model buildings was very similar in many ways. The general development of cracks, the types of cracks, and the failure modes were similar. The effects of the retrofitting measures on the building's behavior were also similar. For the most part, the effects observed in the small-scale model tests were also observed in the large-scale models.

The principal physical difference between the large-scale and small-scale models was the lower gravity loads in the smaller models. These models do not fully replicate gravity loads because the mass loading at the base of the 1:5 model wall was very similar to that at the top of the wall, which was not the case for the half-scale building. As a result, there were small differences in both the out-of-plane and in-plane wall performance. On the other hand, the global performance was very similar.

The clearest difference in the behavior of the large-scale and small-scale models concerned the diagonal cracks in the in-plane walls. Diagonal cracks allow displacements that are cumulative and slippage that is exacerbated by vertical loads. As a result, diagonal cracks were a larger problem in the large-scale model and would be expected to be at least as serious a problem in full-scale buildings. Diagonal cracks near the end of piers and walls are of particular concern in real buildings.

Overturning of walls is less of a problem in full-scale buildings compared to small-scale models because the vertical loads resist overturning. On the other hand, the condition of the base of the walls in the model buildings was very good, while in many actual adobe buildings, the adobe at the base of the walls may have been weakened by exposure to moisture.