Vízügyi Közlemények, 1956 (38. évfolyam)

2. füzet - VII. Kisebb közlemények

(16) Example 2. demonstrates the stress configuration of the floor plate (Fig. 9.) of variable thickness of a tank with dome-shaped cover. Stresses arising between the annular discs are determined by equating their radial displacements. Stresses thus calculated are tabulated under III. From the stress diagram (Fig. 10.) it is evident that tangential stresses have grown suddenly in comparison to the plate of uniform thickness. The thickened portion of the floor plate has become a ring stressed in tension. In example 3. the floor plate of the watertower reservoir of Fig. 11. is treated. First stress-strain formulas of the cylindrical wall under the effect of dislocation Л are derived (35, 37, 42) for conditions of support represented in Fig. 12. and 13. This loading case was not treated in previous papers of the author (Analysis o[ circular plates by the moment distribution method. Vízügyi Közlemények, 1952/1. : Analysis of circular storage tanks with plane cover and floor plates by the moment distribution method. Vízügyi Közlemények, 1953/IL), but it has to be treated in this example. Simplified formulas for high tanks (A. > 6) derived on the basis of the equality sh А. я» eh Я. for loadings according to Fig. 12. and 14 — 16. are also presented here. Similarly to the circular disc the stiffness coefficient of the cylindrical wall is also expressed (38, 39, 42). The calculation is executed for three cases : a) Own weight, b) Water in outer compartment, c) Water in inner compartment. In the first part of the calculation the floor plate is assumed to be horizontally strutted at points „2" and „3". Moments thus obtained are tabulated under IV. without details of computation. Support reactions are determined and — alike to frames with joints free to translate — unit horizontal translation is introduced at points „2" (moment distribution in Fig. 17.) and „3". For the latter loading cases moments (M ) and horizontal reactions (R) are again determined. Results are tabulated under V. and graphically presented in Fig. 18. Annular stresses arising on the lower sections of the cylindrical walls are tabulated under VI. The example shows that moments and annular stresses arising in the cylinder walls of reinforced concrete storage tanks with flat floor and cover plates can be computed with fair approximation by assuming the bottom joint horizontally strutted. Disc stresses, on the other hand, can be determined by distributing on the adjoining disc elements the forces transmitted by the cylinder walls, and acting the plane of the plate, according to their stiffness coefficients. The calculation thus executed is tabulated under VII. Therefrom it is evident that approximate values (Table VII.) hardly differ from exact ones (Table V.).