PSI - Issue 44

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Marius Pinkawa et al. / Procedia Structural Integrity 44 (2023) 2342–2349 Marius Pinkawa, Cristian Vulcu, Benno Hoffmeister / Structural Integrity Procedia 00 (2022) 000–000

2344

CS-1

CS-2

CS-3

CS-4

CS-5

Fig. 1. Analysed double depth frames in cross-aisle (CA) direction

y 0

B*t

A* t

d

s

t

Z

y 0

Y

Y

d

0 Y

t

B* t

B* t

Z

A* t

0 Z

0

s

B*t

t

C* t

A*t

A*t

(a) upright

(b) bracing

(c) pallet beam

(d) base plate

Fig. 2. Cross-sections of elements and detail of the column base (illustrative)

2.2. Assessment procedure of the seismic performance For the seismic performance evaluation elastic time-history (TH) analyses were performed on 2D or quasi-plane 2D (partial 3D) models, for both cross-aisle (CA) and down-aisle (DA) directions. An elastic analysis was chosen because the response was expected to remain mainly in its elastic range. In total 15 earthquake time histories have been applied and the resulting mean values of seismic demands have been evaluated. The accelerograms correspond to the 15 ground motion record set defined in Kohrangi et al., (D.4.2 / STEELWAR project), representing the earthquake hazard at the specific site of the case studies, i.e. Montopoli in Italy. The chosen seismic hazard refers to the typical probability of exceedance of 10% (equivalent to a mean return period of 475 years). Fig. 3 shows the elastic code spectrum, the geometric mean of the 15 accelerograms, the mean of X-component of accelerograms (which was applied in CA direction), and the positions of fundamental periods of the case study frames in CA direction. The seismic performance of the investigated frames was assessed based on the following steps: First, the demand to capacity (D/C) utilization ratios have been computed. The seismic demands were obtained from the time history analyses in terms of stresses, section forces, displacements, drifts, and accelerations. The corresponding capacities were evaluated according to design verification formulas, analytical formulas and/or experimental test data. The spread of D/C ratios within the cross-aisle frame regarding different failure types (cross section, member stability, and connection verification) is exemplarily illustrated in Fig. 4. Second, the “hierarchy of criticalities” has been generated, i.e. the considered failure mode ratios were ordered by their D/C utilization ratios. In this way, the most critical failure modes could be identified, and the hierarchy of criticalities could be compared between the several case studies. The verification of cross-sections, member stability, and connections, and thus the demand to capacity (D/C) ratios were computed for the following members and connections: uprights; bracings (diagonal, horizontal); pallet beams; spacers; bracing-to-upright connections; pallet beam-to-upright connections; roof truss (chords, verticals,