Field Observation and Vulnerability Assessment of Gonbad-e Qābus

Abstract

Gonbad-e Qābus, with a height of 52.8 m that makes it the tallest pure-brick tower in the world, located in the northern part of Iran, represents one of the most magnificent structures of the early Islamic centuries. This structure is still standing among the chaos of urban life and construction, catching the eyes of beholders even from far distances. This paper summarizes the historical and architectural background of this monumental structure and the important restorations carried out mainly in the past century. Various types of existing and potential structural and architectural damages are classified and elaborated in detail, and for each problem, a series of proposed solutions are presented. Utilizing the nonlinear finite-element simulations and equivalent lateral static force method, it is concluded that Gonbad-e Qābus is vulnerable to seismic demands with a return period of 475 years; therefore, retrofit strategies should be considered to improve its seismic performance.