Compression Load Tests on Composite Foundations of Spread Footing Anchored by Helical Anchors

Table 2

Definitions of representative interpretation criteria examined in this study.

Method	Category	Definition of interpreted capacity, Q
Chin method [31]	Mathematical modeling	QCHIN is equal to the inverse slope, 1/m, of the line, s/Q = ms + c, where Q is the load, s is the total displacement and m and c are the slope and intercept of the line, respectively.
Terzaghi and Peck method [32]	Displacement limitation	QT&P is the load that occurs at 1.0 inch (25.4 mm) total displacement.
Slope tangent method [33]	Graphical construction	QST occurs at a displacement equal to the initial slope of the load-displacement curve plus 0.15 inch (3.8 mm).
Tangent intersection method [34, 35]	Graphical construction	QTI is determined as the intersection of two lines drawn as tangents to the initial linear and final linear portions of the load-displacement curve and projected to the load-displacement curve.
L1–L2 method [28–30]	Graphical construction	QL1 and QL2 correspond to elastic limit and failure threshold loads, respectively, as shown in Figure 6.