Design load-carrying capacity estimates and an improved wooden shore setup

The design load-carrying capacities of wooden shores depend on factors, such as the wood species and properties, and construction methods. This paper focuses on the construction methods, including an upright single shore, group of upright shores, group of inclined shores, butt connections and lap connections. This paper reports experiments to obtain critical loads and then developed an empirical equation based on Euler' formula for the critical loads and design load-carrying capacities. The test results show that the critical loads for an upright single wooden shore are greater than the average values for a group of upright shores, and the latter are greater than the average values for a group of inclined shores. Test results also show that the critical loads become smaller when butt or lap connections are used, butt connections possessing greater critical loads than lap connections. Groups of inclined shores are very popular at work sites because they have some practical advantages even though they actually possess inferior critical loads. This paper presents an improved setup for constructing groups of inclined shores. With this method, the inclined shores have larger critical loads than upright shores. The design load-carrying capacities were obtained by multiplying the average critical loads by a resistance factor (or strength reduction factor, ${\phi}$) that were all smaller than 1. This article preliminarily suggests ${\phi}$ factors based on the test results for the reference of engineers or specification committees.