AISC Verification Problem Example II.A-18

Problem Statement

This document presents a comparative study between the published American Institute of Steel Construction (AISC) Design Examples Version 16.0 and the results generated by SDS2 version 2025.01 connection software for Example II.A-18. The central problem statement is to verify the available strength of single plate shear tab of a beam to girder web connection. This connection involves an ASTM A992 W18×35 beam and an ASTM A992 W21×62 girder supporting beam end reactions of RD = 6.5 kips and RL = 20 kips, using an ASTM A572/A572M Grade 50 shear tab. The connection is shown in Figure 1.

Figure 1. Example II.A-18 elevation view

Connection design report output from SDS2 for this connection:

• Allowable Stress Design (ASD).pdf
• Load and Resistance Factor Design (LRFD).pdf

Note: To view the 3D model (U3D) of the structural joint in the PDF files, open the PDF using Bluebeam or Adobe Acrobat Reader.

Validation Method

The connection as shown in the AISC design example II.A-18 (see reference 1) was modeled in SDS2 and a connection design report was generated for both the ASD and LRFD design methods.

The core of this report features a comparison table for each connection limit state, showcasing the calculated capacities from both SDS2 and AISC. The order of the limit state table generally mirrors the sequence in which it was presented in the AISC example problem. This table also highlights the percent difference (% Δ) between these calculated values, providing a clear measure of any discrepancy, if any.

To further enhance understanding, this report includes relevant notes that discuss any differences or assumptions made during the calculation process. In certain cases where AISC did not calculate a connection capacity for a limit state, the connection capacity was back calculated based on the limit state values and documentation for this calculation is provided in the notes. The goal of this comparative study is to evaluate the precision and efficiency of the SDS2 connection design software in contrast to the AISC Design Examples and serves as a guide for better understanding and application of these two design calculations.

Comparison

Comparisons of the limit state checks are presented in Table 1 for ASD and Table 2 for LRFD. The limit state checks and calculated values aligned well between the published AISC Design Example document and the calculation generated by SDS2. The minor differences in calculated values, except where noted, were a result of rounding differences.

Table 1. Capacity comparison table for ASD
Limit state (ASD)	SDS2 Capacity	AISC Capacity	%Δ	Notes
Shear rupture of plate	39.0 kips	39.0 kips	0.0%	1
Block shear rupture of plate	43.6 kips
Rupture of weld to column	-			2
Bolt shear of web bolts	11.9 kips / bolt	11.9 kips / bolt	0.0%
Coefficient for eccentrically load bolt group, C	3.56	3.54	0.6%	3
Bolt bearing on plate	14.63 kips / bolt	8.23 kips / bolt	0.0%	4
Bolt tearout on plate at edge bolt	8.23 kips / bolt
Bolt bearing and tearout on plate at non-edge bolts	14.6 kips / bolt	14.6 kips / bolt	0.0%
Bolt bearing on web	17.6 kips / bolt	12.8 kips / bolt	0.0%	4
Bolt tearout on web at edge bolt	12.8 kips / bolt
Bolt bearing and tearout on web at non-edge bolts	17.6 kips / bolt	17.6 kips / bolt	0.0%
Bolt group shear of web bolts	42.5 kips	-	-	5
Bolt group bearing on plate	44.0 kips	-	-	5
Bolt group bearing on web	47.7 kips	-	-	5
Shear transfer at bolts	42.5 kips	38.9 kips	8.5%	6
Block shear rupture of beam web	63.6 kips	58.7 kips	7.7%	7
Flexure of coped beam	169.2 kips	-	-	8
Rupture of weld to girder web	-	OK	-	9
Shear of support	179.4 kips	-	-	10
Shear yielding of plate	57.5 kips	-	-	11
Flexure of plate	165.7 kips	-	-	11
Shear rupture of beam web	71.4 kips	-	-	11
Shear yielding of beam web	94.2 kips	-	-	11
Connection capacity	39.0 kips	38.9 kips	0.3%

Table 2. Capacity comparison table for LRFD
Limit state (LRFD)	SDS2 Capacity	AISC Capacity	%Δ	Notes
Shear rupture of plate	58.5 kips	58.5 kips	0.0%	1
Block shear rupture of plate	65.4 kips
Rupture of weld to column	-			2
Bolt shear of web bolts	17.9 kips / bolt	17.9 kips / bolt	0.0%
Coefficient for eccentrically load bolt group, C	3.56	3.54	0.6%	3
Bolt bearing on plate	21.9 kips / bolt	12.4 kips / bolt	-0.5%	4
Bolt tearout on plate at edge bolt	12.30 kips / bolt
Bolt bearing and tearout on plate at non-edge bolts	21.9 kips / bolt	22.0 kips / bolt	-0.5%
Bolt bearing on web	26.3 kips / bolt	19.2 kips / bolt	0.0%	4
Bolt tearout on web at edge bolt	19.2 kips / bolt
Bolt bearing and tearout on web at non-edge bolts	26.3 kips / bolt	26.3 kips / bolt	0.0%
Bolt group shear of web bolts	63.7 kips	-	-	5
Bolt group bearing on plate	66.0 kips	-	-	5
Bolt group bearing on web	71.6 kips	-	-	5
Shear transfer at bolts	63.7 kips	58.5 kips	8.2%	6
Block shear rupture of beam web	95.4 kips	88.2 kips	7.5%	7
Flexure of coped beam	254.3 kips	-	-	8
Rupture of weld to girder web	-	OK	-	9
Shear of support	269.1 kips	-	-	10
Shear yielding of plate	86.3 kips	-	-	11
Flexure of plate	249.0 kips	-	-	11
Shear rupture of beam web	107.1 kips	-	-	11
Shear yielding of beam web	141.3 kips	-	-	11
Connection capacity	58.5 kips	58.5 kips	0.0%

Table Notes

Note 1: AISC checks shear rupture, block shear rupture, and weld shear in one lookup value from Manual Table 10-10a.

Note 2: SDS2 shows the weld is sized to develop the full strength of the plate.

Note 3: The AISC C value was back calculated as: C/n * n = 0.885 * 4 = 3.54.

Note 4: AISC checks bolt bearing and tearout strength in one lookup value from Manual Table 10-10b.

Note 5: AISC does not calculate this individual limit state per bolt group.

Note 6: AISC designs the bolt bearing/tearout for eccentricity. SDS2 designs the bearing/tearout limit states for a concentrically applied load and bolt shear for eccentricity since this connection meets the requirements of the conventional configuration per AISC 16th Edition Steel Construction Manual pg. 10-49. For the conventional configuration, the plate bearing and tearout can be checked assuming the reaction is applied concentrically.

Note 7: AISC checks top edge, center, and bottom edge looked up from Manual Table 10-1c. The footnote in Table 10-1C notes that the tabulated values account for a 1/4" reduction in l_eh to account for possible underrun in beam length. The difference in this calculated value is due to AISC is using l_eh of 2.25" where SDS2 is using the full 2.5".

Note 8: AISC only notes that this limit state does not govern.

Note 9: SDS2 checks the weld size is 5/8 * (tab thickness) and shows the weld is capable of developing the strength of the plate. AISC checks the minimum support thickness to match the shear rupture strength of the supporting beam web. AISC does not check that that the weld is capable of developing the strength of the plate.

Note 10: Not checked by AISC, but it does check that the weld can develop strength of web. AISC checks shear yield and shear rupture of the supporting member web. Although not shown in AISC Ex. II.A-18, rupture of the supporting member is checked in AISC Ex. II.A-17B (page IIA-184) and it is noted that shear yielding doesn't control.

Note 11: Not checked by AISC.

References

1. AISC Committee on Manuals, Companion to the AISC Steel Construction Manual Volume 1: Design Examples, Version 16.0, American Institute of Steel Construction, 2023, https://www.aisc.org/publications/steel-construction-manual-resources/16th-ed-steel-construction-manual/manual-companion-for-16th-edition/.