Combined Tension and Bending Loading in Bottom Chord Splice Joints of Metal-Plate-Connected Wood Trusses

Abstract

Metal-plate-connected (MPC) splice joints

were tested in combined tension and

bending to generate data that were used in

the development of a design procedure for

determining the steel net-section strength of

bottom chord splice joints of MPC wood

trusses. Several common wood truss splice

joint configurations were tested at varying

levels of combined tension and bending

loading. The joint configurations were 2x4

lumber with 20-gauge truss plates, 2x6

lumber with 20-gauge truss plates, and 2x6

lumber with 16-gauge truss plates. All the

joints tested failed in the steel net-section of

the truss plates. The combined loading was

achieved by applying an eccentric axial

tension load to the ends of each splice joint

specimen.

Three structural models were developed to

predict the ultimate strength of the steel

net-section of the splice joints tested under

combined tension and bending loading. The

test data were fitted to each model, and the

most accurate model was selected. Data

from other published tests of splice joints

were used to validate the accuracy of the

selected model. A design procedure for

determining the allowable design strength of

the steel net-section of a splice joint

subjected to combined tension and bending

was developed based on the selected

model. The new design procedure was

compared with two existing design methods.

The proposed design procedure is

recommended for checking the safe

capacity of the steel net-section of bottom

chord splice joints of MPC wood trusses

subjected to combined tension and bending.