Abstract
Socket connection,as a main method of accelerate bridge construction is especially suitable for the municipal bridge and other bridges which have the limited construction period.And it does attract a lot of attention to its horizontal bearing capacity such as its seismic performance.Marsh and Motaref used cyclic loading to investigate the horizontal performance of the socket connection in 2011[1,2].But its longitudinal bearing capacity is neglected.
This paper totally studied 3 socket connection specimens with different thickness of bottom plate and compared with the cast-in-place specimen.Bonding failure condition is also considered between the grouting material and socket end.Model sketch is shown in Figure 1,gray part is prefabricated cap;green part is grouting material and red part is prefabricated column.Height of cap is 75 cm,inserted depth of the columns are 63 cm,50 cm,35 cm and the corresponding thickness of the bottom plate is 12 cm,25 cm,40 cm,respectively.
Figure 1 Model sketch
When bonding is well between grouting material and column end,the compress stress distribution of the whole structure is shown in Figure 2,longitudinal load is 5 000 k N,thickness of the bottom plate is 25 cm.
Figure 2 Compressive stress distribution under bonding well condition
When bonding failure between grouting material and column end under long service period,the distribution of compressive stress is shown in Figure 3.
Figure 3 Com pressive stress distribution under bonding failure condition
Comparing Figure 2 and Figure 3,after bonding failure between grouting concrete and column end,the main force is supported by the bottom plate of cap.After bonding failure,tensile stress of steel bars in the bottom plate increases from 78 MPa to 139 MPa.The tensile stress distribution is shown in Figure 4.
Figure 4 Bar stress distribution in the bottom plate of cap
About the longitudinal stiffness of each specimen,it can be reflected by the loading deformation,for the cast-in-place specimen,its longitudinal deformation is 0.52mm at the center of bottom plate.Deformation of other socket connection at the center of bottom plate is shown in Table 1.The longitudinal deformation of socket connection specimens is larger than the cast-in-place specimen and with the thickness of bottom plate decreasing,the longitudinal deformation increasing more and more.
Table 1 Deformation of socket connection at the center of bottom plate underbonding well condition
When bonding failure between grouting material and column end,the longitudinal deformation is shown in Table 2.
Table 2 Deformation of socket connection at the center of bottom plate underbonding failure condition
Comparing Table 1 and Table 2,after the cohesion invalid between grouting material and column end,the longitudinal deformation of the whole specimen increases about one time at the center of bottom plate.
Socket connection can have the comparative longitudinal bearing stiffness and capacity for the cast-in-place specimen.Bonding condition between grouting material and column end as an important factor influences the longitudinal performance of socket connection.When bonding is invalid,the longitudinal stiffness shows a discount.