Unified concepts of constitutive modelling and numerical solution methods for concrete creep problems

Technical Report · Thu Jan 01 04:00:00 EST 1976

OSTI ID:6786855

Argyris, J H; Pister, K S; Szimmat, J; William, K J

An internal variable model was developed for concrete creep with the following features: creep strain is a linear functional of stress history; application or removal of stress produces instantaneous elastic response; upon removal of stress, creep deformations partially recover, approaching in the limit an irrecoverable part. The mechanism of each creep component is affected by temperature, humidity, and loading age. The internal state variables were derived from concrete creep data with loading ages ranging from 7 to 4560 days and temperatures from 20 to 95 C. Several aging models were examined for which the parameters were determined via least square optimization. A root mean square criterion was used to assess the approximation. A step by step algorithm was developed for incremental solution of the time-dependent creep process, noting that the governing equation of evolution lends itself to an economic computer solution without storing previous results. The one-dimensional constitutive statements were extended to multiaxial conditions and subsequently projected from the local level onto the structural level via finite elements (incremental initial load method). The creep behavior of a prestressed concrete reactor vessel was examined for a loading history which includes hygrothermal effects due to drying and heating as well as prestress and cycling pressure.

• Research Organization: Stuttgart Univ. (TH) (Germany, F.R.). Inst. fuer Statik und Dynamik der Luft- und Raumfahrtkonstruktionen
• OSTI ID: 6786855
• Report Number(s): N-78-20370; ISD-185
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
220200* -- Nuclear Reactor Technology-- Components & Accessories
36 MATERIALS SCIENCE
360603 -- Materials-- Properties
AGING
BUILDING MATERIALS
CONCRETES
CONTAINERS
CREEP
HUMIDITY
MATERIALS
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
NUMERICAL SOLUTION
PRESSURE VESSELS
PRESTRESSED CONCRETE
STATIC LOADS
STRAINS
STRESSES
TEMPERATURE EFFECTS
TIME DEPENDENCE