PSI - Issue 70

Umeshkumar T. Mourya et al. / Procedia Structural Integrity 70 (2025) 35–42

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2. Experimental investigation EN15512 (2020) recommends a single cantilever test to ascertain the looseness in the connections. The load is applied on the connection to alternatively create sagging and hogging bending moment, and the slip is noted between the changing stiffness. The looseness values are equivalently converted to imperfection values and are implemented in the numerical model to account its effect on the frame behaviour. The following sections describe the experimental evaluation of the looseness. 2.1. Test configurations The connection configurations investigated in this study comprise four upright cross-sections and three beam cross sections with two end-connector depths. The upright profiles are designated with depth, width and thickness with a prefix T, for example T090 × 70 × 1.6 has 90 mm depth, 70 mm width and 1.6 mm thickness. Similarly, the beam is also designated but with the prefix B, for example, B50 × 080 × 1.6 has 50 mm width, 80 mm depth and 1.6mm channel profile. The beams are formed into a box section by crimping to channel sections facing opposite together, hence the flange is two times thicker than the web. The beams having depths 80 and 100 mm have 150 mm deep end-connectors and 3 tabs and the 140 mm deep beam has 5 tabs and 250 mm deep end-connector. The details of the 12 configurations of the connections are presented in Table 1. Due to the proprietary nature of these components, detailed dimensions cannot not be disclosed here.

Table 1. Details of the connection configurations S. No. Configuration

$ N

# d

Upright

Beam

tab

tab

1 2 3 4 5 6 7 8 9

B1T1 B1T2 B1T3 B1T4 B2T1 B2T2 B2T3 B2T4 B3T1 B3T2 B3T3 B3T4

T090×70×1.6 T090×70×1.8 T100×70×2.0 T100×70×2.5 T090×70×1.6 T090×70×1.8 T100×70×2.0 T100×70×2.5 T090×70×1.6 T090×70×1.8 T100×70×2.0 T100×70×2.5

B50×080 B50×080 B50×080 B50×080 B50×100 B50×100 B50×100 B50×100 B50×140 B50×140 B50×140 B50×140

3 3 3 3 3 3 3 3 5 5 5 5

150 150 150 150 150 150 150 150 250 250 250 250

10 11 12

$ Number of tabs in the end-connector

# Depth of the end-connector

2.2. Test Setup and Instrumentation This study employs a cantilever bending test configuration to assess connection looseness by analyzing the moment-rotation behavior. The experimental setup follows the guidelines outlined in EN 15512 (2020) (refer Fig. 3). The test assembly consists of a beam with an end-connector attached to the upright. The 700 mm long upright is secured to a rigid column using 10 mm diameter bolts and steel plates positioned at the top and bottom to distribute load and minimize stress c oncentrations near the bolt holes. Additionally, a wooden block is placed inside the upright’s profile to prevent localized buckling at the bolted locations. The load is applied by means of hydraulic push-pull jack, having a capacity of 10 ton, to the 600 mm long beam at an offset of 400 mm from the upright's face. To ensure