Search Results (2)

This study develops a comprehensive analytical framework to predict the flexural behavior of externally prestressed steel–concrete composite I-girders (EPCIBs) subjected to positive bending. The analytical model is formulated using strain compatibility and internal force equilibrium and accounts for elastic–plastic behavior of concrete, structural steel, and external tendons. Validation against three independent experimental programs demonstrated strong accuracy, with differences in ultimate moment within 5–8%, mid-span deflection within 6–10%, and tendon stress increments within less than 6% compared with measured results. Additional validation against nonlinear ABAQUS finite element (FE) models confirmed similar accuracy, with ultimate moment discrepancies generally below 8%. A comprehensive parametric study quantified the sensitivity of EPCIB behavior to span length, shear-span ratio, prestressing level, concrete slab properties, and steel-section geometry. Increasing the initial prestressing force from 160 kN to 300 kN increased the ultimate moment capacity by 10–15% and reduced service-level deflection by 18%. Increasing slab thickness from 60 mm to 120 mm enhanced capacity from 230 kN·m to 380 kN·m (a 65% increase), while increasing slab width from 600 mm to 1200 mm produced a moderate 10–12% capacity gain. Enhancing steel section dimensions showed the highest influence: increasing bottom-flange width from 200 mm to 300 mm increased strength by 30–35%, increasing bottom-flange thickness from 8 mm to 14 mm improved capacity by 55–60%, and increasing web depth from 200 mm to 400 mm more than doubled the flexural capacity (up to 150% increase, reaching 780–800 kN·m). Web-thickness variations (4–8 mm) produced smaller gains of 25–30%. Full article

Composite steel girders with concrete have been used for many years and advances in structural and fabrication technology have established their optimization. One of the changes in structural steel I-beams during the past few years has been the availability of web corrugation. The economic design of steel girders normally requires thin webs. Moreover, using externally prestressed tendons as a strengthening technique controls deflections and stresses. However, this strengthening technique causes shear buckling of the steel beams. In this study, the flexural behavior of externally prestressed composite steel-concrete I-beams with a single and double corrugated web was experimentally and numerically investigated. Three simply supported prestressed steel-concrete composite I-beams with single corrugated web (SCW) and double corrugated web (DCW) were tested under four-point loading. The tested beams were externally prestressed by using straight tendons along the full length. The experimental results showed that using SCW was more efficient in shear buckling resistance than DCW with the same equivalent web thickness. The ABAQUAS package was used to simulate the nonlinear behavior of the tested beams. The developed model was validated against the experimental results to carry out a parametric study in order to investigate the effect of various parameters on the behavior of the composite beams with SCW and DCW. Using stiffeners at the loading points as deviators to maintain the prestressed tendon positions increased the beam capacity and improved the beam performance. Full article