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8.1 Creep

This section describes the input syntax of creep models. Two models are available: metal creep and transient creep. Transient creep applies to the specific creep of concrete at elevated temperatures. For the creep of concrete under long term load, use viscoelasticity [Ch.7].

(syntax)

$\begin{figure}\centering \begin{tabbing} \texttt{'MATERI'} \\ [-1.0ex] \rule{14... ...{fc}}$_{r}\,$ \texttt{\textit{crpfac}}$_{r}\,${]} \end{tabbing} \end{figure}$

CREEP

COMPLI specifies that the uniaxial equivalent creep strain is translated to a multiaxial strain vector via the compliance matrix.

CRPVAL

nu is a value to set up the compliance matrix. By default nu is Poisson's ratio $\nu$ as specified in the linear elastic input.

TRCRP

specifies the transient creep for concrete at elevated temperatures: value fc is the uniaxial compressive strength f_c , value crpfac is the creep factor k . The transient creep strain is

$\displaystyle \dot{{\boldsymbol{\varepsilon}}}^{{\mathrm{tr}}}_{}$ = $\displaystyle {\frac{{\alpha k}}{{f_{\mathrm{c}}}}}$ $\displaystyle \dot{{T}}$ $\displaystyle \boldsymbol\sigma$

(8.1)

With k the creep factor (tests reveal 1.8 $\leq$ k $\leq$ 2.35 ), $\alpha$ the coefficient of thermal expansion, f_c the uniaxial compressive strength at room temperature 20 °C , T the temperature and $\boldsymbol\sigma$ is the stress.

(file.dat)

 1   POISON 0.2
     CREEP  COMPLI
     TRCRP  30.  2.35

For background theory of transient creep and other effects of thermal loading in DIANA see the article by De Borst & Peeters [23].

Next: 8.2 Shrinkage Up: 8. Creep and Shrinkage Previous: 8. Creep and Shrinkage Contents Index

DIANA-9.3 User's Manual - Material Library
First ed.

Copyright (c) 2008 by TNO DIANA BV.