Determination of shear support capacity of transfer beam with varied section

In the RC structure with transfer beam, if the beam is fixed with the column under the transfer layer, it will cause very big reaction of the support at the supporting point and can cause the serious breaking because the section of the transfer beam is very big. It’s not easy to make the section big for the whole length, so I studied about how to applicate the transfer beam with varied section to increase the capacity by changing the section of the beam around the supporting point. In this thesis, I suggested the formulars of the shear capacity of transfer beam with varied section by using the program ABAQUS Keyword:transfer, beam, section, shear, capacity Received 12 July 2021|Revised 22 August 2021 | Accepted 26 August 2021


Introduction
There are two types of transfer beams. One is below convexed transfer beam, and another one is the haunched transfer beam ( Figure 1). Generally, the section of transfer beam is very big and the column under the transfer layer is relatively weak, and the linear stiffness of the beam is much bigger than the one of the wall in the structure with transfer beam [1][2]. If the transfer beam is fixed with the column under the transfer layer, there can be very big outer face bending moment in the bearing wall and can exceed the bending moment of the bearing wall. It can cause the crack and breaking on the bearing wall. The beam end bending moment can be lowered in the way of hinge joint between the transfer beam and the column below. In general making the end of the beam section small can resolve the pin structure.
This caused the below convexed transfer beam. Such below convexed transfer beam can effectively reduce the beam end bending moment but the bending moment at the span of the beam can be increased. In this thesis [6][7], if the opening in the frame-supported shear wall is near the supporting point of the transfer beam or if the shear capacity of the transfer beam is not enough, haunch have to be installed in the supporting point of the transfer beam.
In this thesis [8], through the experiment of the structure of the transfer beam with haunch, I proved that the structure of the transfer beam with haunch not only effectively prevent the excess of the stiffness of the transfer beam by reducing the section of the beam but also prevent the creation of the "stronger columns and weaker beams"mechanism. I also proved that the structure with haunch is "stronger columns, weaker beams and even stronger joints"structure and the seismic performance is good. After the crack appeared in the wall beam with haunch, it slowly worked as arch and the bearing structure was similar to the "tiearch" of the beam with constant section. The transfer beam of which the height of the section at the supporting point hs is higher than the height of the section at the center of span h is called transfer structure with haunch.

The Calculation of Shear Capacity of Sloping Section
Transfer beam with varied section has got various sections in its span, so after the crack appears at the sloping section, the "tie-arch" bearing structure has different characteristics from the transfer beam with constant section. Because of that, according to each bearing structure, the formulars of shear capacity of two types of transfer beams with varied section is determined. The main factors affect the shear capacity of the transfer beam of varied section are section size, pressure strength of concrete, shear-spane ratio, the rebar ratio of longitudinal rebar and horizontal distribute rebar and so on.

Below convexed transfer beam
To determine the formular of shear capacity according to the bearing characteristics of the below  (1) where -shear force that affects concrete and horizontal distribuite rebar which contains the curved rebar inside the concrete. In case the shear span ratio and supporting length are not considered the calculation can be simple. (1-1) Comparing the calculation result and experimentation result is as follows.
in equation 1 and in equation 1-1.

Transfer beam with haunch
To determine the formular of the shear capacity of the transfer beam with haunch, the finite element analysis about the calculation model as follows (Figure 14).

calculation of shear capacity of transfer beam with varied section
Generalizing upper formulars of shear capacity of two kinds of transfer beam with varied section, one formular of shear capacity of transfer beam can be come by. (10) where -correction factor of shear capacity.
-below convexed transfer beam: -transfer beam with hauch: As you can see, in case of the transfer beam with varied section, the height of section can be assumed as the height on the span center to check the crack of the sloping section.

Concluding remarks
In