Civil Engineering Reference
In-Depth Information
Finally, screw down the nuts. If the purlin deflects overly, lift it a little before screwing the
nuts. This method is simple and convenient in application.
L
0
100
100
10 turnbuckle
10 turnbuckle
φ
8 bar
Round or rectangular timber
Fig. 5.17 Strengthening of purlin
(replacing purlin with bracketing beam, unit: mm).
Fig. 5.18
Strengthening of purlin (with round tension rods, unit: mm).
5.5.2
Strengthening of Wooden Stairs
Most damages of wooden stairs are caused when the close-to-ground part of the skew beam
is subjected to humidity or insect pests, which results in settlement of stairs. Additionally,
there are other damages such as loose trigonal timber resulting from long service.
Wooden stairs to be strengthened are of two types, namely exposed beam and hidden
beam stairs. For exposed beam stairs, it is feasible to replace the trigonal timber or add
splints. As for hidden beam stairs, the damaged skew beams are usually replaced by new
ones.
Before the skew beam is strengthened or replaced, temporary supports should be installed
if necessary. When the skew beam is replaced, trigonal timber should be fabricated accu-
rately and nailed firmly to the beam, while the nailing of step boards should be uniform. In
addition, the upper and lower ends of the skew beams of stairs should be fixed firmly, and
the regions close to the wall or on the ground should be treated to prevent corrosion.
When skew beams of hidden beam stairs are fabricated, the disposition of step slots in
the skew beams should be accurate, steps should be connected to the beam firmly, the ends
of the skew beams of stairs should be fixed firmly, and the connection of the skew beams
should also be reliable.
