Impact of Environmental Conditions on Rammed Earth Heritage Buildings Seismic Performance

Heritage buildings in high seismic hazard areas usually have high vulnerability due to many factors affecting their seismic performance, including material properties, construction procedures applied and preservation conditions. One especially vulnerable structural system used for thousands of years, is the one using compacted soils as a construction material, called rammed earth structure. As rammed earth walls dry and harden, material properties and strength increases. However, weather phenomena during time like storms, floods, ice and snow change walls water content and could change overall structural behavior if there is no protection covers over walls. The aim of this work is to analyze the influence of weather on the seismic performance of rammed earth walls. Water content profiles of two selected walls were calculated and evaporation flux was modelled from experimental data in reduced scale models inside a climatic chamber. After, a finite element model was used for computing dynamic linear and nonlinear performance of earthen walls subjected to selected strong motion records, in different weather conditions. Results indicated that wall shear modulus increase as matric soil suction increase, rising earthen wall’s stiffness in dry conditions, increasing vibration frequencies. Under different water content situations, wall’s stiffness change, vibration frequencies decay and seismic performance changes consider-ably. Nonlinear walls’ behaviour indicates variable differences between dynamic results under saturation and under residual dry conditions. Those differences will have considerable impact in the design, construction, strengthening or rehabilitation programs on rammed earth buildings, impact that has been neglected when considering earthquake resistance and vulnerability of heritage constructions.