Lateral Capacity Assessment of the Main Pyramid of Huaca de la Luna (Peru) Using 2D Finite Element Macroblock Model

This study contributes to the structural assessment of the main pyramid in the archaeological complex of Huaca de la Luna, Peru. Built with millions of adobe bricks by the Moche civilization (200–850 A.D.), the monument is one of the largest adobe structures in the world. Located in a seismically active area, the monument shows signs of severe natural and anthropogenic damage. The pyramid was built as a succession of taller and larger platforms, each formed by erecting adjacent but disconnected vertical piers made of adobe masonry. A multiscale 2D nonlinear FE model is introduced for assessing the contribution of this pier architecture to the dynamic response of the pyramid. A representative cross-section of the pyramid is analyzed under plane strain conditions. Critical regions are modelled with individual piers represented by macroblocks separated by frictional interfaces, while a continuous description is adopted for the remaining part of the model. The analysis is performed in Abaqus/CAE Explicit using concrete-damaged plasticity and Mohr-Coulomb formulation for adobe construction and soft soils, respectively. The time-evolution of elastic strain and dissipative plastic energy is used to follow the development of local damage conditions up to structural collapse. The structural assessment includes (i) a quasi-static analysis aiming to predict the stress state due to gravitational loads, and (ii) dynamic analysis to identify lateral capacity and failure mechanisms triggered by monotonically increasing ground acceleration. Sensitivity analyses was conducted to evaluate the effect of the contact friction coefficient and the number of macro-blocks used to discretize the critical area.