Civil Engineering Reference
In-Depth Information
Figure 1.7
Struts-and-ties models showing effectiveness of diagonal rebars
1.4.3.3 Knee Joint under both Closing and Opening Moments
The rebar arrangement in a knee joint subjected to both closing and opening moments, as in
earthquake loadings, is shown in Figure 1.8. This arrangement is a combination of the two
schemes designed separately for a closing moment (Figure 1.5d) and for an opening moment
(Figure 1.6f).
Knee joints can also be strengthened by adding a fillet, as shown in Figure 1.8(b). The rebar
arrangement could be simplified in such a joint, because the stresses at the joint region are
significantly reduced.
1.4.4 Comments
Despite the clear concepts inherent in the struts-and-ties models, they are difficult to use in the
actual design of the main regions of beams for three reasons.
Figure 1.8
Knee-joint rebar arrangement for both closing and opening moments (earthquake loading)
