Main Challenges of National Seismic Guidelines for Lifeline Utilities in Iran

Despite many seismic design and retrofit standards, codes and guidelines for buildings and bridges, there is a big lack of similar documents for lifelines in the world. Japan and USA have already developed some seismic guidelines for their lifelines. More than one decade, Iran has done several seismic damage evaluation and retrofit projects for lifeline utilities in big cities and mainly in capital city of Tehran. This made the essential background for developing national seismic guidelines for design, damage evaluation and retrofit of lifelines including gas, water, power, wastewater and tele-communication systems. A guideline for seismic loading on lifelines, similar to the Iran 2800 seismic standard for buildings is developed as the seismic loading base for the seismic design guidelines. There are also 5 separated but harmonized guidelines for seismic design developed for 5 mentioned utilities. Seismic damage evaluation and retrofit guidelines are also additionally prepared for the same lifelines in 5 separated and harmonized volumes. The main points in the new serial seismic guidelines for the country may be summarized as two levels of input seismic hazard of 75 and 475 years return period earthquakes, two levels of performance as non-stop operation and minimum-stop operation expectation against two seismic hazard levels, respectively. Two design methods of ASD (Allowable Stress Design) and Ductility Design are mainly used for two performance levels, respectively in the guidelines. The main points in seismic loading guideline are using seismic coefficient method for calculating the inertial forces, while response displacement method is accepted for soil-structure interaction forces on buried structure such as pipelines, tunnels and reservoirs.