This study examines the mechanical performance of blended sand core glass fiber-reinforced polymer (GFRP) pipes with varied cross-sectional geometries under transverse compressive loads. The multi-layered sandwich walls of the pipes are constructed using unidirectional, chopped strand, and surface mats made of glass fibers embedded in Crystic 491E isophthalic polyester resin, with a blended sand core bonded using Dicyclopentadiene (DCPD) resin. The effective elastic properties and tensile, compressive, and shear strengths of each layer are estimated using micromechanics-based analytical methods. Finite element analyses (FEA) of quasi-static lateral compression tests are performed using commercial software to assess failure and damage characteristics under high compressive strains. For intralaminar damage in the GFRP layers, a continuum damage mechanics approach incorporating Hashin’s failure criteria is employed. Interlayer delamination is modeled using surface-based cohesive behavior with a penalty stiffness method, while damage initiation is predicted using the energy-based Benzeggagh-Kenan (B-K) criterion. Numerical results are validated against experimental data for three cross-sectional geometries: circular, box-shaped, and semi-elliptical. The finite element model predictions align closely with experimental findings for ring stiffness (5% deflection) calculations. The geometries were designed to meet the requirements specified in ASTM D3262 and D2412. Among the evaluated designs, box-shaped pipes, which had a greater wall thickness relative to other cross-sectional dimensions, demonstrated the highest stiffness, significantly exceeding the 125psi stiffness class. In all geometries, damage initiation was observed at the inner surface along the bottom location of the symmetry line.