Parametric study for post-tensioned composite beams with external tendons

Abstract

Strengthening of bridge superstructures composite beams with external post-tensioned tendons is a good technique for strengthening the existing structures. In this study, a numerical model is illustrated to study the nonlinear simulation of composite beams stiffened with externally post-tensioned tendons. The accuracy of the developed numerical model is validated using comparisons between the numerical and existing test data. The influence of various strengthening parameters is investigated, which include draped versus straight tendons, tendon length, the effect of post-tensioning on reinstating the flexural behavior of an overloaded beam, tendon eccentricity, and the degree of shear connection. A good agreement between the proposed model and the test data is obtained. The results demonstrate that at the same tendon eccentricity, the trapezoidal profile shows better behavior for the strengthened beams. However, more ductility is obtained when using the straight tendon profile. Applying post-tensioning through the beam of full length helps to reduce the creation of fatigue cracks, which always start at stress raisers, and subsequently increases the fatigue life of the composite beam. Also, the external post-tensioning effectively maintains the flexural behavior of the overloaded strengthened beam after unloading in comparison to the un-strengthened beam. It is observed that 80% degree of shear connection or higher is recommended to obtain the desired performance of the external post-tensioning force for strengthening composite beams.

A nonlinear geometric model for pre-stressed steel–concrete composite beams

“…For the particular case of beam BS2, there exists a more significant difference in the ultimate tendon force and load path evolution since the start of the analysis. However, a similar trend has been also reported by El-Zohairy and Salim [6] as shown in the Fig. 14.…”

“…The study shows that the influence of secondary moments on moment redistribution is less pronounced in aramid fiber reinforced polymers (AFRP) tendons than in carbon fiber reinforced polymers (CFRP) ones. El-Zohairy and Salim [6] present a FE threedimensional model using the ANSYS [7] software to model external pre-stressed composite beams including nonlinear material and geometric behavior. Therein, varying parameters such as tendon profiles, tendon length, degree of shear connection and pre-stressed load level are studied.…”

Behavior of Strengthened Composite Prestressed Concrete Girders under Static and Repeated Loading

“…El-Zohairy and Salim [14] performed a parametric study for posttensioned composite beams with external tendons. An FEM model is presented to simulate composite beam strengthened with externally posttensioned tendons, and the analysis results are veri ed with existing test data.…”

Fatigue loading characteristic for the composite steel-concrete beams

“…This can be considered a high cyclic fatigue load pattern with an average fatigue life over one million cycles. By adjusting the total number of shear connectors over the span length, we can control the degree of shear interaction [9,17]. For the effect of the shear interaction between the top flange of the steel beam and the concrete slab on the overall behavior of the composite beam, seven beams with seven different degrees of shear connection were evaluated under named sections ( (HB-N) where N was the degree of interaction as a percentage from full shear interaction case).…”