Sommario
Si considera una struttura reticolare le cui aste presentino valori del carico di snervamento aleatori e comunque distribuiti attorno ai loro valori medi. Si dimostra che il coefficiente di sicurezza al collasso plastico calcolato deterministicamente, assumendo per ciascuna asta i carichi di snervamento pari ai loro valori medi, è maggiore od uguale al valor medio dei coefficienti di sicurezza di tutte le strutture che la aleatorietà dei carichi di snervamento rende possibili.
Summary
The safety coefficient relevant to the plastic collapse is considered for a framed structure, when the yield stresses of its beams are random quantities, however distributed. A value for the safety coefficient may be obtained through a deterministic calculation, assuming for each beam the yield stress equal to its average value. It is demonstrated that such a value of the safety coefficient is greater, or at least equal, to the average value of the safety coefficient of all the feasible structures corresponding to the various yield stresses of the beams.
Abbreviations
- F :
-
factor which multiply all loads
- n :
-
number of beams of the framed structure
- N i :
-
axial force in the beami, (i=1, ...,n)
- N si :
-
yield limit ofN i
- \(\bar N_{si} \) :
-
average value of the random variableN si
- P i (x):
-
probability density ofN si , i. e.,P i (x)·dx=Prob. (N si =x±dx/2)
- S :
-
safety coefficient of the structure relevant to the plastic collapse, for the actual values ofN si
- \(\bar S\) :
-
average value ofS
References
J. R. Benjamin,Probabilistic Structural Analysis and Design, ASCE, Journal of the Structural Div. ST 7, July 1968.
J. F. Borges andM. Castagnetha,Structural Safety, Laboratorio Nacional de Engenharia Civil, Lisboa, Nov. 1968.
V. Franciosi,Scienza delle Costruzioni, Edizioni Liguori, Napoli, 1965.
A. M. Freudenthal,Critical Apraisal of Safety Criteria and their Basic Concepts, Preliminary Publication of the 8th Congress of the IABSE, New York, September 1968.
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Additional information
The equationN sj =x±Δ/2 means thatN sj assume one value in the intervalx−Δ/2,x+Δ/2.
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Castellani, A. Average value of the safety coefficient in a framed structure corresponding to random distributions of yield stresses. Meccanica 4, 281–285 (1969). https://doi.org/10.1007/BF02133094
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DOI: https://doi.org/10.1007/BF02133094