🏗️ Base Plate Deformation
Conventional approaches for steel-to-concrete connection calculation generally assume that the anchor base plate does not deform. Load distribution is simplified such that deformations are distributed linearly across the surface of the base plate. But does the base plate always behave according to these assumptions? 🤔
🖥️ Let's test this assumption in the #RFEM program from #DlubalSoftware. This program provides tools to simulate and design steel-to-concrete connections using a numerical FEA model. The reference example will be the connection of an HEB 200 column to a base plate anchored with four M24 anchors. We will compare two base plates with different thicknesses:
1️⃣ Rigid (40 mm)
2️⃣ Flexible (15 mm)
👉 Bending:
In the case of a flexible base plate, the distribution of contact stress leads to a reduction in the lever arm. The base plate corners near the tensioned anchors become compressed against the concrete, which induces additional prying forces. As a result, the tensile force in the anchors increases compared to the rigid base plate version.
👉 Compression:
From the contact stress distribution image, it is evident that for the flexible base plate, the concentration of contact stress around the profile projection results in higher values than in the case of the rigid base plate.
👉 Tension:
Similar to the bending case, a flexible base plate can generate compressive contact stress in the corners, causing the formation of prying forces. Although this effect is not as pronounced in the studied example, the contact stress distribution and anchor force values clearly show its occurrence.
📝 Modeling steel-to-concrete connections using numerical FEA models provides a realistic simulation of the base plate behavior based on its rigidity. Besides providing a more accurate determination of the contact stress distribution in the base plate and the tensile forces in the anchors, it is possible to simulate rotation in the anchor base plate. For the flexible variant, this rotation will be larger, resulting in greater deflection of the modeled structure.
