Structural Concrete - Hassoun

16.6 Design of Frame Hinges 565
For a uniform load on top member BC,let
(
I2
K 1 = 2 + × h )
I 1 L
M B = M C =− wL2
6K 1
M A = M D = M B
2
H A = H D = 3M A
and
h
For a uniform load on half the top member BC, let
Then
M A = wL2
8
M C = wL2
8
K 2 = 1 + 6
(
1
− 1
)
3K 1 8K 2
(
2
− 1
)
3K 1 8K 2
H A = H D = wl2
8 × 1
K 1 h
M(midspan) = wL2
8 + M B
V A = V D = wL
2
(
I2
I 1
× h L
V A = wL
2 − V D and V D = wL
8
)
M B = wl2
8
M D = wL2
8
(
2
+ 1
)
3K 1 8K 2
(
1
− 1
)
3K 1 8K 2
(
1 − 1
4K 2
)
16.5 GENERAL FRAMES
The main feature of a frame is its rigid joints, which connect the horizontal or inclined girders of the
roof to the supporting structural members. The continuity between the members tends to distribute
the bending moments inherent in any loading system to the different structural elements according
to their relative stiffnesses. Frames may be classified as
1. Statically determinate frames (Fig. 16.11a).
2. Statically indeterminate frames (Fig. 16.12).
3. Statically indeterminate frames with ties (Fig. 16.13).
Different methods for the analysis of frames and other statically indeterminate structures are
described in books dealing with structural analysis. Once the bending moments, shear, and axial
forces are determined, the sections can be designed as the examples in this book are. Analysis may
also be performed using computer programs.
16.6 DESIGN OF FRAME HINGES
The main types of hinges used in concrete structures are Mesnager hinges, Considére hinges, and
lead hinges [19]. The description of each type is given next.