Modeling, Analysis and Application of Dhajji-Dewari Structures in Pakistan

Abstract

Ohajji-Oewari (0-0) is the name given to construction composed of traditional timber braced framing and masonry infill, which is the prevailing construction for residential buildings in the northern parts of Pakistan and India, including Kashmir. It is also used in other parts of the world. In Britain, it is termed half timbered, in Germany, fachwerk, in France, colombage, and in Turkey Baghdadi, himis, dizeme. Ohajji means "interconnected" or "Patch work quilt" and dewari means "wall" in Kashmiri. It is constructed using locally available construction materials and traditional building techniques. The performance of 0-0 in the 2005 Kashmir Earthquake provided important information for historic preservation and lessons for the construction of affordable earthquake-resistant structures in those regions of high seismic hazard where modern, Western construction techniques are impractical. In the aftermath of this tragic earthquake, the Earthquake Reconstruction and Rehabilitation Authority (ERRA) in Pakistan decided against rebuilding lost housing stock using reinforced concrete and recommended the use of 0-0 Structures instead. There are more than 120,000 0-0 housing units in earthquake-prone regions of Pakistan. Buildings in the remote, mountainous regions of Pakistan have been badly damaged by moderate and severe earthquakes. Reinforced concrete buildings have fared poorly because the reinforcement detailing and concrete quality are both substandard. This form of construction requires engineering analysis and design and specialty construction that are generally unavailable in remote regions. 0-0 construction has performed comparatively better because engineering is not required and construction can be performed by locals using techniques passed down through generations. Consider the 2005 earthquake in Pakistan. The epicenter of the moment magnitude Mw=7.6 earthquake was in Kashmir. The earthquake shaking destroyed 460,000+ homes, 5,000+ schools and nearty -800 health facilities Page vi across 4000 villages, leaving 3.5 million people without shelter and access to schools and health care. Experts observed that 0-0 houses had performed reasonably well although severe damage was observed and collapses occurred. Many locals started rebuilding their homes after the earthquake using traditional 0-0 construction, because a) 0-0 construction was known to them and outside construction resources were not needed, b) the materials required for construction, timber and masonry, were readily available, and c) other building materials such as concrete and reinforcement were unavailable. Importantly, emphasis was placed on providing shelter for families ahead of winter, regardless of whether it was resistant to earthquakes or not. It is therefore timely to study the vulnerability of 0-0 construction and to develop cost-effective strategies and technical guidelines for their rehabilitation with the long-term goal of preventing substantial loss of life in DO construction in future earthquakes. In this project/thesis study is carried out regarding the seismic response of 0-0 components, connections, and systems. The study developed analytical and numerical modeling tools and techniques. The research/thesis delivered simplified analysis tools to assess the seismic performance of 0-0 construction, perform vulnerability assessments.