Adding composite truss to improve mechanical properties of reinforced concrete T-girder bridge

Abstract

To solve the problem of insufficient transverse connection of T-girder bridges, this paper investigated the strengthening method of two composite trusses symmetrically installed in mid-span. The composite truss included two top plates, four diagonal braces, and one horizontal brace. An experimental investigation was carried out to study the mechanical properties of reinforced concrete T-girder using single-point loading method under four load cases. The experimental results showed that the maximum transverse stiffness of T-girder specimens strengthened with composite trusses improved by 12.4% compared with control beams. Simultaneously, it had an excellent restraining effect on the cracks development. The maximum percentage decrease in the deflection corresponding to the maximum load when the reinforced concrete T-girder strengthened with composite trusses over the control beam of up to 39.7 was observed. In addition, the load transverse distribution coefficient was investigated according to rigid-jointed slab (girder) method. The composite trusses were chosen as intermediate diaphragm to calculate moment of inertia. The analytical model was in an accurate with the experimental result under the same loading condition. The optimize spacing of composite trusses was given from 600 mm ( L/10) to 1200 mm ( L/5), and thickness of top plate was 30 mm when the load transverse distribution coefficient was homogeneously distributed. Finally, a three-dimensional finite element model was used to evaluate the effectiveness of composite trusses.

Investigation on mechanical performance of prestressed concrete box‐girder bridge strengthened using composite trusses with different shapes

“…As shown in Figure 16, δ 1À1 , δ 2À2 , and δ 3À3 are composed of three components: vertical deflection of the girder (ω), deflection caused by the torsion angle (α= αb 1 2 ), and deflection caused by the upper flange (f ). Therefore,…”

“…Small‐ and medium‐span bridges constitute approximately 80% of all bridges in China, 1,2 among which T‐shaped and box‐shaped bridges are the most typical structural shapes 3 . The diaphragm is one of the essential components of these bridges, which can transfer the load along the transverse direction and ensure that all the main girders support the force simultaneously, thus reducing the deflection and bending moment of a single beam 4–7 .…”

“…The results showed that the KCTs reduced the crack width, improved the failure mode and load transverse distribution, and reduced the maximum deflection by 38.6%. Yang et al 1 observed that using KCTs to strengthen a T‐beam bridge can improve the rigidity of the bridge.…”