Simplified Computation of a Base-Isolated Structure

This chapter explains how to carry out a simplified calculation of the seismic isolation of buildings and bridges. The importance of always carrying out the simplified calculation before proceeding with a more in-depth analysis is highlighted. A calculation example is then presented referring to a real building currently under construction in Taiwan. The calculation is carried out considering the use of three different types of seismic isolators: high-damping rubber bearings, lead rubber bearings, and sliding pendulum isolators. The results are then compared. All the details necessary for the design of the building are also examined: gaps to allow relative movement between the building and the foundations, details of stairs and elevators, connections of electrical cables and pipes between the underground and the isolated building, protection from fire of the isolators. An example of the calculation of a seismically isolated bridge is then given, using lead rubber bearings and sliding pendulum isolators alternatively and explaining the function of mechanical fuses in railway bridges.