Page 52 - Modern Steel Construction (April 2019)

16 Rules for

Connection

Design

BY CAROL DRUCKER, SE, PE, PENG, BILL THORNTON, PE, PHD,
DOMINICK D’ANTONIO, PE, PATRICK J. FORTNEY, SE, PE, PENG, PHD, AND SNEHAL SUPE

Structural connections connect everyone—engineers, detailers, fabricators

and erectors. And the better they are designed, the better it is for

all parties involved with steel framing systems.

STRUCTURAL STEEL CONNECTIONS have a direct impact 3. Coordinate the ller plates at slip-critical connections.
on a project’s success. Oversized holes with slip-critical bolts are commonly preferred at

Those of us who design and build with steel are well aware of bolted ange-plated beam-to-column moment connections to allow
this, as well as the fact that connections should be strong and stiff for additional erection tolerance. Due to possible overrun of the beam

enough to resist the required loads, cost-effective to fabricate and depth and ange tilt, ller plates are needed at the beam bottom ange.
3

safe and easy to erect. Sound advice and insightful tips from indus- The gap left for the llers is typically ¼ in. to 8 in. If multiple llers
try experts can help you raise your connection game and achieve are used, there is a 15% reduction in bolt slip resistance due to the fac-

the most ef cient balance between these fundamental criteria. tor for llers, h f . The penalty for multiple llers should be considered
Here are some tips from around the structural steel world—educa- and coordinated with the fabricator and erector. To avoid an increase

tion, design, detailing, fabrication and erection—on how to pro- in bolts due to multiple llers, the fabricator can provide alternate ller

vide ef cient connection design and avoid costly missteps. thicknesses for the connection (but this may increase cost.) The exact

1. Read user notes and Commentary in the Speci cation. ller used will depend on the actual gap (see Figure 1).
The user notes in the AISC Speci cation for Structural Steel Buildings

(ANSI/AISC 360) contain helpful information that is not consid- Fig. 1.

ered Speci cation language. For example, the user note in Speci ca-
tion Section J4.3 indicates that typical cases where the block shear
reduction coef cient, U BS , should be taken as 0.5 are illustrated
in the Commentary, which contains a wealth of knowledge and

design guidance for the Speci cation.

2. Con rm the erector’s preferred hole type for single-
plate beam-to-column connections. While short slotted holes
are typically preferred at double-angle connections and end plate
connections, erector preferences at single-plate connections to

column anges and webs may vary. Some erectors prefer short-
slotted holes to allow for additional erection tolerance while oth-
ers prefer standard holes to help plumb the column. The exact,
preferred hole type should be con rmed with the erector before

nalizing the design.
52 | APRIL 2019