Research on Static Behavior of Concrete-Filled Steel Tubular Arch-Column-Tie Beam Joints

In order to study the reasonable construction t echnology and mechanical properties of arch-tie beam joints， a new construction form of concrete-filled steel tubular circular arch beam-inclined column-tie beam joint was proposed based on the structural joint of the Shenzhen Museum. Static loading tests and finite element simulations were conducted on a 1∶3 scale model of the joint to verify its reliability. The testing program included two conditions： one with prestressed bars installed and one with them removed. The test results showed that the region of highest stress was located at the junction between the tie beam and the circular arch beam. The yielding area of the tie beam was more extensive in the case without the prestressed bars. Upon reaching the design load， the joint essentially remained in an elastic state， meeting the design requirements. Under both loading conditions， when the load reached 1.66 times the design load， extensive local areas of the steel components reached the yield strain， yet no obvious damage was observed， indicating a substantial safety reserve. The installation of the prestressed high-strength bars reduced the axial elongation of the tie beam by 48%. The finite element simulation results indicated that the junction of the circular arch beam and the tie beam was subjected to a complex stress state with high concentrations， making it the critical region governing the joint's bearing capacity. The joint reached its ultimate bearing capacity when the web of the tie beam and the steel tube of the circular arch beam yielded over a large area. Compared to the case with prestressed bars， the case without them exhibited a 6.4% increase in the relative vertical displacement at yield and a 12.4% reduction in stiffness. When the peak bearing capacity was reached， both the steel plates and the concrete in the core of the joint remained in an elastic state， ensuring reliable load transfer.