In-Plane Seismic Capacity of Interlocking CSEB and Fired Clay Brick Masonry Piers: A Comparative Numerical Study

Sammanfattning

Nepal is located in one of the most seismically active regions in the world, and the 2015 Gorkha earthquake clearly demonstrated the vulnerability of non-engineered masonry buildings. In the reconstruction efforts following the earthquake, interlocking Com- pressed Stabilised Earth Blocks (CSEB) have been highlighted as a potentially more seismically robust and at the same time more sustainable alternative to conventional fired clay brick masonry. Despite practical experience from their use, systematic engi- neering comparisons between interlocking CSEB and fired clay brick masonry under comparable conditions remain limited. In this master’s thesis, the in-plane seismic response of masonry wall panels, also re- ferred to as piers, made of interlocking CSEB and fired clay brick is compared through non-linear finite element analyses. The models were developed in ABAQUS using de- tailed micro-modelling, in which all materials were modelled explicitly and contacts and interactions allowed separation, re-contact, and sliding. The piers were analysed using static displacement-controlled pushover analyses. Two idealised support condi- tions were considered: cantilever and fixed at both ends. These were chosen to represent limited and strong restraint at the top of the wall, respectively. The effect of vertical pre-compression is examined through one low and one high pre-compression level, and selected cases also include vertical reinforcement based on the principles of the Nepal Building Code (NBC). The results are presented in the form of pushover curves (base shear, V , versus top lateral displacement) and through interpretation of damage patterns and governing failure mechanisms. The comparison shows how geometry (slenderness), support condi- tions, and pre-compression influence capacity, stiffness, drift capacity, ductility, energy absorption, and governing failure mechanisms, including the difference between shear- dominated mechanisms (diagonal localisation) and flexural- or rocking-dominated me- chanisms. The influence of reinforcement is discussed in terms of how it modifies the failure process and post-peak response, and how this relates to the prescriptive recom- mendations in the NBC. Overall, the study provides a mechanistic basis at pier level for understanding the differences between the systems and for guiding continued work towards building-level analysis and future validation against experimental data.