scholarly journals Application of the Generalized Nonlinear Constitutive Law to Hollow-Core Slabs

2021 ◽  
Author(s):  
Natalia Staszak ◽  
Tomasz Garbowski ◽  
Barbara Ksit
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Crack Opening ◽  
Constitutive Law ◽  
Fe Model ◽  
Hollow Core ◽  
Linear Finite Element ◽  
Deformation State ◽  
Non Linear ◽  
Nonlinear Constitutive Law

The non-linear analysis of hollow-core concrete slabs requires the use of advanced numerical techniques, proper constitutive models both for concrete and steel as well as particular computational skills. If prestressing, cracking, crack opening, material softening, etc. are also to be taken into account, then the computational task can far exceed the capabilities of an ordinary engineer. In order for the calculations to be carried out in a traditional design office, simplified calculation methods are needed. Preferably based on the linear finite element (FE) method with a simple approach that takes into account material nonlinearities. In this paper the simplified analysis of hollow-core slabs based on the generalized nonlinear constitutive law is presented. In the proposed method a simple decomposition of the traditional iterative linear finite element analysis and the non-linear algebraic analysis of the plate cross-section is used. Through independent analysis of the plate cross-section in different deformation states, a degraded plate stiffness can be obtained, which allows iterative update of displacements and rotations in the nodes of the FE model. Which in turn allows to update the deformation state and then correct translations and rotations in the nodes again. The results obtained from the full detailed 3D nonlinear FEM model and from the proposed approach are compared for different slab cross-sections. The obtained results from both models are consistent.

First and Second Order Elastoplastic Analyses of Thin-Walled Metal Members using Generalized Beam Theory

2018 ◽  
Author(s):  
Miguel Abambres
Keyword(s):  
Finite Element ◽  
Stainless Steel ◽  
Cross Section ◽  
Beam Theory ◽  
Second Order ◽  
Flow Rule ◽  
Non Linear ◽  
Thin Walled ◽  
Shell Finite Element ◽  
Generalized Beam Theory

Original Generalized Beam Theory (GBT) formulations for elastoplastic first and second order (postbuckling) analyses of thin-walled members are proposed, based on the J2 theory with associated flow rule, and valid for (i) arbitrary residual stress and geometric imperfection distributions, (ii) non-linear isotropic materials (e.g., carbon/stainless steel), and (iii) arbitrary deformation patterns (e.g., global, local, distortional, shear). The cross-section analysis is based on the formulation by Silva (2013), but adopts five types of nodal degrees of freedom (d.o.f.) – one of them (warping rotation) is an innovation of present work and allows the use of cubic polynomials (instead of linear functions) to approximate the warping profiles in each sub-plate. The formulations are validated by presenting various illustrative examples involving beams and columns characterized by several cross-section types (open, closed, (un) branched), materials (bi-linear or non-linear – e.g., stainless steel) and boundary conditions. The GBT results (equilibrium paths, stress/displacement distributions and collapse mechanisms) are validated by comparison with those obtained from shell finite element analyses. It is observed that the results are globally very similar with only 9% and 21% (1st and 2nd order) of the d.o.f. numbers required by the shell finite element models. Moreover, the GBT unique modal nature is highlighted by means of modal participation diagrams and amplitude functions, as well as analyses based on different deformation mode sets, providing an in-depth insight on the member behavioural mechanics in both elastic and inelastic regimes.

Specimen positioning effect on microshear test: Non-linear finite element analysis

2012 ◽  
Vol 28 ◽  
pp. e15-e16
Author(s):  
L.H.A. Raposo ◽  
L.C.M. Dantas ◽  
T.A. Xavier ◽  
A.G. Pereira ◽  
A. Versluis ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Element Analysis ◽  
Linear Finite Element ◽  
Non Linear

Nichtlineare Finite-Elemente-Analyse von Flachdecken im Bereich von Randstützen/Non-Linear Finite Element Analyses of Edge Column-Slab Connections

Bauingenieur ◽  
2015 ◽  
Vol 90 (05) ◽  
pp. 209-219
Author(s):  
Marcus Ricker ◽  
Frank Häusler
Keyword(s):  
Finite Element ◽  
Finite Element Analyses ◽  
Linear Finite Element ◽  
Experimentelle Untersuchungen ◽  
Finite Elemente ◽  
Non Linear

Während das Querkrafttragverhalten von Flachdecken im Bereich von Innenstützen (Durchstanzen) Gegenstand zahlreicher Untersuchungen ist, fehlen für Rand- und Eckstützen durch theoretische und experimentelle Untersuchungen abgesicherte Tragmodelle. Um das Tragverhalten im Bereich von Randstützen näher zu untersuchen, wurde neben vier Durchstanzversuchen eine umfangreiche Parameterstudie mit zwei nichtlinearen Finite-Elemente-Programmen durchgeführt. Dabei stand neben dem Einfluss der bezogenen Ausmitte e/c auf die Tragfähigkeit von Platten mit und ohne Durchstanzbewehrung der Einfluss der Vorspannung im Vordergrund. Es zeigte sich, dass das e/c-Verhältnis unabhängig von der Versagensart einen wesentlichen Einfluss auf die Durchstanztragfähigkeit hat. Eine Vorspannung erhöht die Durchstanztragfähigkeit signifikant bzw. reduziert die erforderliche Durchstanzbewehrungsmenge. Eine Steigerung der Maximaltragfähigkeit gegenüber gleich dicken hochbewehrten Stahlbetonplatten ist jedoch nur in geringem Maße möglich.

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