Connection design can be difficult to teach, given the detailed nature of the topic and the fundamentally three-dimensional behavior of most connections. However, connections are critically important, and lessons learned in the study of connection design, including load path and identification and evaluation of failure modes, are general and applicable to structural design broadly. IDEA StatiCa uses a rigorous nonlinear analysis model and has an easy-to-use interface with a three-dimensional display of results (e.g., deformed shape, stress, plastic strain) and thus is well suited for the exploration of the behavior of structural steel connections. Building on these strengths, a suite of guided exercises that use IDEA StatiCa as a virtual laboratory to help students learn about concepts in structural steel connection behavior and design was developed. These learning modules were primarily targeted to advanced undergraduate and graduate students but were made suitable for practicing engineers as well. The learning modules were developed by Associate Professor Mark D. Denavit from the University of Tennessee, Knoxville.
Learning Objective
After performing this exercise, the learner should be able to describe prying action, the parameters that affect it, and how it affects the design of structural steel connections.
Background
Bolts in tension can be subjected to greater force than expected due to a phenomenon known as prying action.
While not limited to T-stubs and angles, prying action is most clearly identified and evaluated with these components. Consider the all-bolted double-angle connection shown in the figure below. The beam, acting as a chord or collector, is subject to 60 kips of tension (for simplicity, shear in the beam is neglected). 5 bolts connect each angle to the column flange for a total of 10 bolts between the angles and the column flange. Based on a simple analysis, one may expect the tension in each bolt to be 60 kips/10 bolts = 6 kips per bolt. However, the actual tension force is greater, about 14 kips per bolt for the connection shown below, because the toes of the angles are bearing on the column flange and the bearing force adds to the bolt tension.
