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One-dimensional semi-analytical model on longitudinal thermal loads of a tram track pile-plank structure buried beneath the pavement

Shan Yao, Zhou Xiangliang, Zhou Shunhua

Archives of Civil and Mechanical Engineering

2021

Vol. 21, no. 1

599--616

A novel pile-plank-supported ballastless tram track is employed in southeast of China to mitigate the foundation differential settlement in soft soil regions. In this structure, the channel rails are directly combined with the plank by fasteners and pads. In situ measurement data reveal that the foundation differential settlement is well controlled by this structure and the internal forces of the plank mainly depend on temperature variation. To assess the structural safety and improve the reinforcement design for the pile-plank structure, an efficient and precise calculation algorithm for internal forces of the structure is urgently required. In this work, a one-dimensional (1D) model is proposed to evaluate the longitudinal forces of the embedded pile-plank structure due to temperature variation. The constraints of rails and surrounding concretes (i.e., overlying pavement and the supporting layer) on the embedded structure are considered. The semi-analytical solution of this model is derived and a comprehensive calculation procedure is proposed. Based on the project of Shanghai Tram Line T1, a case study is undertaken to validate the proposed model. The results indicate that the maximum longitudinal displacement of the plank increases with the temperature variation. The critical displacement appears when the temperature variation rises to 15 ℃. The calculated longitudinal forces of the plank are in accordance with the in situ measurement data. This model provides a strong base to the reinforcement design of the pile-plank-supported ballastless tram track.

Optimal design of thin-walled columns for buckling under combined loadings controlled by displacements

Krużelecki J., Stawiarski A.

Czasopismo Techniczne. Mechanika

2010

R. 107, z. 4-M

61-84

In this paper the problem of the optimal design of thin-walled tubular columns under axial compression and torsion controlled by displacements is investigated. A radius of cross-sectional circular profile varying along the axis of the shell-column as well as a wall thickness, which lead to the maximal displacements caused by loadings before the structure buckles are sought. Both global (buckling of a column) and local (wall buckling of a shell) stability of a structure are taken into account. The geometry of the structure is approximated by the convex Bezier polynomial. The results are obtained using the simulated annealing method.

W artykule badano problem optymalnego kształtowania cienkościennych kołowych kolumn poddanych działaniu osiowego ściskania i skręcania sterowanych przemieszczeniowo. Poszukiwano zmiennego wzdłuż osi kolumny-powłoki promienia kołowego profilu przekroju oraz grubości ścianki, które prowadzą do maksymalnego przemieszczenia spowodowanego obciążeniami do momentu utraty stateczności. Uwzględniono zarówno globalną (wyboczenie kolumny), jak i lokalną (wyboczenie ścianki powłoki) stateczność konstrukcji. Geometrię konstrukcji aproksymowano wypukłymi wielomianami Beziera. Optymalizację przeprowadzono, stosując metodę symulowanego wyżarzania.