Civil Engineering Reference
In-Depth Information
3.10.4 Halving joints
Halving joints are used frequently at the ends of statically determinate bridge beams,
in order to reduce the depth of the support system. Truss analogy is the best tool
for designing the reinforcement in these complicated zones, and gives direction on
its arrangement and curtailment. A typical truss analogy for a halving joint is shown
in Figure 3.17
(a). The analogy makes clear the following points which may not be
obvious:
•
At point A, the bottom boom tension steel must be fully anchored, by turning up
the bars for instance.
Member B, the bottom boom tension steel for the reduced height section must
be carried back so that it can transfer its force into the truss system. Note that
anchorage lengths have not been shown, and this steel would need to be fully
anchored beyond point C. This force also increases the compression force in
member D, the lower part of the last compression strut of the deeper section.
Member E, the last web tensile member, has its tension signifi cantly increased due
to the increased compression in D.
•
•
Figure 3.17
Halving joint
