La Sagrada Familia: Approaches to Seismic Analysis

Abstract

La Sagrada Familia in Barcelona is currently 135 years into its construction, with an expected completion date of 2026. Since its inception by Antoni Gaudí in 1882, radical analysis and design methods have been required to imagine its architectural form and understand the engineering performance of what will be, once complete, the tallest church in the world. Gaudí famously used hanging chain models to realise the catenary form of his structures, a method which pre-empted modern form-finding software and enabled him to devise an organic optimised form long before this could be achieved with computers.

When Gaudi designed the Sagrada Familia in the late 19th century, the influence of seismicity on structures was not well understood, and therefore not considered in the original design. To justify the seismic design of six towers due for construction on top of La Sagrada Familia today, a detailed non-linear model has been created, and subjected to time history analysis. The model is excited in the time domain by the Spanish code design level earthquake, filtered by the presence of the church below. The analysis represents the non-linear behaviour of masonry to assess the ductility capacity and collapse limits of the towers. The model has been calibrated using on-site measurements taken of the dynamic properties of the current structure, modified by assumptions about cracking under seismic excitation.

This paper describes the modelling and analysis methodology undertaken, before highlighting further potential uses of the techniques.