Experimental investigation on the load carrying capacity of modified purlin to rafter connection
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Date
2017-06
Authors
Sheikh Hazwan Bin Humayunkabir
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Abstract
In Malaysia, almost all houses in rural area are non-engineered structures. The
roof of these houses is susceptible to failure and many types if roofing failure can be
expected. This study examines the pull-out capacity of several simple connections
meant for tying the timber purlin to rafter. The types of connections are single nail,
double nail, nail plus metal strap and nail plus rope. The tests were conducted on timber
type Damar Minyak and Dark Red Meranti, both are classified under strength group 5
and 6. The wind load was applied in the form of pull-out force generated via in-house
frame and Universal Testing Machine. The results showed that, for single nail
connection, two phases of response were observed. Other types of connections showed
three distinct phases from beginning until failure. This phenomenon is particularly true
for both types of timber. In the case of timber type Damar Minyak, the maximum pull out capacity exhibited by the nail and metal strap connection (1.55 kN) followed by
nail and rope (1.485 kN), double nail (0.825 kN) and single nail (0.445 kN). However,
for timber type Dark Red Meranti, the use of double nail spaced at 30 mm apart
exhibited the highest pull-out capacity (2.5 kN) followed by nail and metal strap (1.8
kN), nail and rope (1.53 kN) and single nail (1.22 kN). It was also noted that stronger
timber grade developed higher nail to timber connection compared to lower timber
grade. The most efficient connection for timber type Damar Minyak and Dark Red
Meranti was found to be nail plus rope and double nail, respectively.