Civil Engineering Reference
In-Depth Information
upper chords are calculated as eccentrically compressive members and the web and lower
chords as axial compressive or tensile members in accordance with rules in
Design Criteria
for Concrete Structure
.
58
58
58
29
4
3.01
5
3.01
6
7
1
298.5
5.85
201.7
9
8
10
11
3.0
3.0
2.85
loads and axial forces in bars (kN)
physical dimension of bars (m)
(a)
4
5
6
−985
7
1
201.7
298.5
11
9
8
10
(b)
4
5
6
−985
7
1
201.7
268.5
9
10
8
11
(c)
Fig. 3.45 The change in axial forces before and after retrofitting.
(2) Method of sticking steel
a. Technique: strengthening technique of sticking steel is widely used in both tensile
and compressive lack of carrying capacity. Much attention should be paid to the quality
of anchoring steel angles at tensile bars and the spacing between lacing bars in case of
instability in the angle. Two types of sticking steel are provided: dry condition type (see
Fig. 3.46(a)) and wet condition type (see Fig. 3.46(b)).
Fig. 3.46
The cross sections of members with sticking steel method.
This method performs especially well in raising the capacity of bar members in roof truss
systems, at the cost of minor effect on decreasing the number of cracks in tensile members,
especially for dry condition type.
b. Procedure: design for sticking steel angle to retrofitting reinforced concrete roof trusses
is summarized as follows:
a) Calculate the internal force under service loads following the scheme described previ-
ously;
