PSI - Issue 5

Ivan Baláž et al. / Procedia Structural Integrity 5 (2017) 1057 – 1064 Ivan Baláž / Structural Integrity Procedia 00 (2017) 000 – 000

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Baláž, Ároch, 1991) and realised in 1993. In this proposal took part also one of the best Slovak structural engineer Ing. Ján Bustin, PhD., (*17.02.1926, † 11.02.2017). The bridge was strengthened by adding a Warren-type truss as a middle web to make a two-cell box girder along the whole length of the bridge. Six- meter spacing of the “nodes’’ and a diagonal area of 12,000 mm 2 provide fictitious wall shear thickness t s = 2.73 mm (Fig. 4). Adding a truss middle web along the length 140 m has increases the effective breadth when taking into account shear lag phenomenon caused by live (variable) loading at the support in the form of a framed pendulum wall (critical section in Fig. 1) on the Bratislava side. Table 1 shows rating factors calculated according to (ON 73 6220, 1976) and relating standards (ČSN 73 6203, 1986) and (ČSN 73 6205, 1984): a) without any changes, b) taking into account proposal for exception, c) taking into account proposal for exception and strengthening.

Fig. 4. Strengthening by adding the middle truss web along the length 140 m at Bratislava end of the bridge.

Fig. 5. Stress distributions in the critical section: a) before strengthening (left), b) after strengthening by inserting middle truss web (right) for the internal forces: N = – 370 kN, M y = – 255 956 kNm, V z = – 14656 kN, B = – 6142 kNm 2 , T t = – 10151 kNm.

8. Conclusion

Design, description and experience with 45 years old cable-stayed SNP Bridge over river Danube in Bratislava, Slovak Republic. Imperfection measurements, inspections, calculation of rating factors and evaluation of load carrying capacities, proposal for exception, strengthening and its influence. Local and global buckling combined with shear lag effects. Influence of torsion at box girders. Development of cable-stayed bridges and position of the SNP Bridge in the world rankings of the large span cable-stayed bridges after 45 years from it opening.