PSI - Issue 84

Stefano Bozza et al. / Procedia Structural Integrity 84 (2026) 686–693

691

Fig. 2: Mean maximum displacements of load bearings and joints.

Regarding the results of the reference model (with prestress and 2% damping), almost all load bearings exceeded the displacement capacity reported in the design documentation, with the exception of devices in PI04. Maximum longitudinal displacements in the first half of the bridge are slightly smaller compared to those in the second half of the bridge (5.5 cm versus 6.4 cm), probably related to the planimetric layout (the first part of the deck is curved, while the second one is straight). Instead, transversal displacements in AB01 and AB02 are very similar. Comparing the results of the reference model with those of other cases, neglecting the prestress action in the piers shows small differences in the results, while a high influence of the damping ratio can be noted. In fact, the displacements reported for the “NO Prestress (2%)” case show little differences to the reference model, mostly between -2% and +3%. The “Prestress (5%)” case and the “NO Prestress (5%)” case also show very close results, but with displacements from 18% to 30% smaller than those of the reference model. Assuming a higher damping reduced the maximum demand to capacity ratio from 1.30 to 1.03 in the longitudinal direction and from 2.6 to 2.0 in the transversal direction. Although the nominal displacements capacity is exceeded, total displacements are small compared to the dimensions of the devices (about 70 cm), thus loss of support in load bearings is not considered an issue for the case study bridge. 4.3. Joints and shear keys free displacements Closure of deck joints (labelled IJ for initial joint, MSJ for mid-span joint and FJ for final joint) and longitudinal displacements in shear keys (SK 1, SK 2, SK 3) were evaluated, and mean maximum values are reported in Fig. 3. The joint closure displacement capacity was assumed equal to the clearance between elements (gap between the abutment rear wall and the deck for the initial and final joint, and gap between the two parts of the deck for the mid span joint), while the nominal capacity specified in the design documentation of the bridge was assumed as the displacement capacity of shear keys.