Seismic Fragility and Thermal Performance Assessment of Reinforced Concrete Frames Incorporating Shale Powder under RPS 2011 Loading

The increasing environmental impact of conventional concrete production and the seismic vulnerability of reinforced concrete structures in Morocco have encouraged the development of sustainable alternative construction materials. This study evaluates the seismic and thermal performance of reinforced concrete frames incorporating shale powder from the Settat-Khouribga region as a partial replacement for natural sand.

Four concrete formulations containing 0%, 5%, 15%, and 25% shale substitution were evaluated using calibrated finite element modeling. Linear elastic analyses were done in SAP2000 as per the Moroccan seismic code RPS 2011. Pushover and Incremental Dynamic Analysis (IDA) analyses were carried out in OpenSees software with 12 spectrum-consistent ground motions. Thermal behavior was determined using steady-state analysis in ANSYS Mechanical.

The F15 mixture, which consisted of 15% shale substitution, demonstrated the best behavior in terms of structure and thermal stability. Compressive strength was achieved at 22.3 MPa, and the ductility index rose to 3.97. Median capacity for collapse was measured at 1.19 g, and the probability of surpassing the design level of earthquake protection is 9.8%, while in the case of the reference concrete, the same indicator is 12.1%.

The mixture F15, which was made up of 15% shale replacement, showed the best performance in respect of structural properties and thermal stability. Compressive strength was observed to be equal to 22.3 MPa, while the ductility factor increased to 3.97. The median collapse capacity reached 1.19 g, and the possibility of exceeding earthquake protection design levels was calculated to be 9.8%, as compared to 12.1% for reference concrete.

The addition of 15% shale powder is considered to achieve an optimum combination of seismoprotection, structural flexibility, and energy savings. The obtained results confirm the possibility of using the shale powder as a sustainable construction material for reinforced concrete structures in seismically active areas of Morocco.