Lateral Load Behavior of Traditional Assam-Type Wooden House

Abstract

The traditional Assam-type wooden house is one of the very few housing systems in India that has performed exceptionally well during past earthquakes. Due to the high seismicity of the northeastern region of India, local people have developed a unique earthquake resistant housing typology using locally available materials. The houses have a number of features, such as the light mass of the walls and roof, good wall-to-wall connection, and flexible joints that contribute to their earthquake safety. In spite of these exceptionally good features, these houses have not received due attention and their behavior has not been studied so far. In this study, full-scale frames of a single-story Assam-type house were tested under slow cyclic and monotonic lateral loads. Results showed excellent behavior in terms of lateral drift and ductility capacity without any significant drop in lateral load capacity even under large lateral drift. Failure was primarily due to the separation of secondary stud members at connections and flexural failure of vertical posts at a very high lateral drift levels during monotonic loading. However, the connections of the main posts with the foundation and with the top beam remained intact during the tests. Simplified analytical models were developed for lateral load analysis of the Assam-type housing frames and their lateral load behavior was validated with the experimental results. Finally, a simple empirical equation was developed for estimation of lateral load capacity of such frames from regression analysis of the experimental data.