Experimental and numerical study of shear bearing capacity of geopolymer concrete beams with stirrup

Purpose This study investigates the shear performance of reinforced geopolymer concrete (GC) beams, focusing on how shear span ratio, stirrup ratio and concrete strength affect behavior. Using experimental and numerical methods, this study aims to develop reliable models for predicting diagonal cracking loads and ultimate shear capacity, thereby supporting the structural application of GC. Design/methodology/approach Eleven reinforced GC beams were tested under static four-point loading with different shear span ratios, stirrup ratios and concrete strengths. Load, displacement, strain and failure modes were measured. A diagonal cracking load formula was developed through regression analysis, and shear capacity was predicted using a model based on the modified compression field theory (MCFT), which considered equilibrium, compatibility and material behavior. The model was validated using test results. Three-dimensional finite element models were also created in ABAQUS to simulate mechanical behavior and failure, further confirming experimental findings. Findings Shear capacity decreased with increasing shear span and decreasing stirrup ratios. Higher stirrup ratios improved crack control. Concrete strength significantly influenced behavior under large shear spans. Proposed models showed good agreement with test results, and finite element simulations validated failure modes and load–displacement behavior. Originality/value This study investigates the shear behavior of reinforced GC beams through experimental, analytical and numerical methods. The proposed model incorporates the unique properties of GC, including a lower elastic modulus, high binder content and distinct tensile and compressive strength values. By adjusting parameters in the MCFT, the model improves the accuracy of shear capacity predictions compared to conventional concrete models.