PSI - Issue 78

Fabio Micozzi et al. / Procedia Structural Integrity 78 (2026) 1451–1458

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repeated for 10 times. The test is passed if no damage is reported. No specific requirements are given to guarantee that the school desk is a safe shelter in case of falling debris in case of earthquakes and the imposed vertical load (1kN) appears inadequate for this purpose. 2.2. Proposed testing procedure for impact loads As discussed in the introduction, a testing procedure should be easily replicable. Accordingly, the test methodology previously adopted by the authors in the SAFE project was abandoned given that realizing a block of bricks is time consuming (for each weight drop a new assembly is required) and the replicability of the tests is limited due to inevitable movements and rotations of the mass while falling. In addition, a uniform mass falling on the desk, although might sound impressive in terms of total amount, is not the most demanding loading condition, as a smaller footprint might generate much more damage. Following these considerations and taking as reference the loading condition in EN 1729-2 (CEN 2023), the proposed impact test uses a spherical steel mass that is dropped in the symmetry plane perpendicular to the longer horizontal side at 100 mm from the edge. In this way, the same loading point for static testing is replicated. Replicability of the tests is higher as compared to other shapes as possible rotations of the falling mass do not change the shape of the impact footprint. 3. Experimental results 3.1. Description of the impact test The tests were performed on July 15 th , 2025, using a spherical steel mass of 100 kg (diameter about 29 cm) dropped from 150 cm above the tabletop. The instrumented school desk and the steel sphere before testing are shown in Fig. 3. The sequence of the impact test is summarized in Fig. 4 from the moment the sphere is released to the moment the sphere impacts the tabletop and then bounces upwards and moves out of the desk. The damaged school desk after the impact is shown in Fig. 5. The plywood tabletop was removed (Fig. 5b) to show the minor bending damage to the perforated steel sheet.

Fig. 3. Instrumented school desk ready for the impact tests (the 100 kg steel sphere is on the left).