Flexural behaviour of headed bar connections between precast concrete panels

Bending Tests of Connection Structure of Precast Concrete Slabs using Perfobond Strip

“…In replacing the slab of girder bridges, a precast concrete slab is often used in order to shorten the construction period on site. In this case, the precast concrete slabs are required to connect together, and conventionally the connection structures with the loop reinforcements [1] or the headed bars [2] are often used. However, it is expected to develop a connection structure with further reduced the dimension and the work-in-site than conventional ones.…”

Headed Bar Connections Between Precast Concrete Elements: Design Recommendations and Practical Applications

“…Headed bar spacing and lap length were varied in groups 4 and 5 respectively. Four flexural specimens, (see Figure 4), were tested in four-point bending with the headed bar joint located in the tension zone of the constant moment region [18]. Load was applied via four independent hydraulic jacks, forming two line loads 600 mm apart, from the underside of the specimen fed by a single oil supply to maintain even pressure.…”

“…However, strains close to yield were recorded in the offset flexural specimen, indicating increased out-ofplane stresses within the joint. Further details can be found in references [17,18].…”

“…STM1 accounts for the reduction in strut depth due to vertical offsets but also reduces the headed bar capacity to account for bending which is assumed to arise from eccentricity of loading [1]. The first two authors have previously shown [18] that headed bar bending did not significantly affect the strength of B2-26-2H20-S-10 with 10 mm out-of-plane offset. Consequently, the effect of vertical offsets is considered in STM2 through only the reduction in strut depth shown in Figure 7.…”

“…Flexural yield was achieved in B2-39-2H20-S-0 with two top 20 mm transverse bars, 12 mm shear studs and joint concrete cylinder strength of 39 MPa. Crack widths in the flexural headed bar tests[18] were greatest at the precast-to-joint interface crossed by two headed bars, but still within the limit of 0.4 mm imposed by EC2[19] at SLS for concrete inside buildings.In tests where joint failure occurred prior to headed bar yield, joint strength of both tension and flexural specimens increased with concrete strength. However, flexural joint strengths were greater than estimated with section analysis from corresponding tension tests.…”