Design and seismic performance evaluation of 3D frame structures using advanced nonlinear static analysis method (granted by CNCSIS)
Summary In recent years, non-linear inelastic analysis
methods of steel and reinforced concrete frame structures has become
the focus of intense research efforts because of rapid development of
computer technology and the need of implementation in the new design
codes, the more rational advanced analysis techniques and
performance-based seismic design procedures.
the rapid advancement of computer technology, research works are
currently in full swing to develop the advanced inelastic analysis
methods. In spite of the availability of some fem algorithms and
powerful computer programs, the non-linear inelastic analysis of real
large-scale frame structures still posses huge demands on the most
powerful of available computers and still represents unpractical tasks
to most designers. On the other hand, structural response to strong
earthquake ground motions cannot be accurately predicted due to large
uncertainities and the randomness of structural properties and ground
motion parameters. Consequently, excessive sophistication in structural
analysis is not waranted.
The need for accurate yet computational efficient tools for
the non-linear analysis of 3d frame structures forms the main
motivation behind of this work. The research project is intended to
overcome the existing inconveniences and develop an integrated system
for advanced structural analysis and seismic performance evaluation of
3d steel and reinforced building frameworks with rigid or flexible
Chiorean,C.G.A fast incremental-iterative procedure for ultimate strength analysis and design of composite steel-concrete cross-seections, Proceedings of International Conference STESSA 2012, Chile.
Chiorean C.G., Tarta G., Barsan G.M., Gobesz ZS,
Nedelcu M., Computer based nonlinear analsysis method for seismic
performance assesment of 3D frameworks, Proceedings ofInternational Conference STESSA 2012, Chile.
Chiorean, C.G., Barsan, G.M., Ciplea C, A fast iterative procedure for ultimate strength analysis and design of composite cross-seections, Proceedings of International Symposium IABSE-IASS, Taller, Longer, Lighter, London, UK.
Chiorean, C.G., Barsan G.M., Nedelcu, M., Varga S.,
Ciplea, C, Large deflection distributed plasticity analysis pf 3D
composite steel-concrete frameworks, Proceedings of International Symposium IABSE-IASS, Taller, Longer, Lighter, London, UK.
GFAS-A finite element system for geotechnical applications (granted by
GEOSTRU SOFTWARE); Application of finite element method in Geotechnical Engineering
GFAS is a finite element package that has been developed
specifically for the analysis of deformation and stability analysis in
geotechnical engineering problems.
The basic program features include:
Graphical input of geometry models:
The input of soil layers, structures, loads and boundary conditions is
based on convenient CAD drawing procedures, which allows for a detailed
modeling of the geometry contour. From this geometry model, a 2D finite
element mesh is easily generated.
Automatic mesh generation: GFAS allows for automatic
generation of structured and unstructured 2D finite element meshes with
options for global mesh refinement. The program
contains a built-in automatic mesh generator that considerably
simplifies construction of the finite element model. Both triangular
(3-noded or 6-noded) and quadrilateral (4-noded or 8-noded) elements
Higher-order elements: Quadratic 8-node and 6-node triangular elements are available to model the deformations and stresses in the soil.
Optimization of the matrix bandwidth to reduce the
computer storage and calculation time can be performed by the program
using internal re-numbering of the system equations.
Staged constructions: Complex multi-stage models can be created and analyzed such as: tunnels, excavations, embankments, soil reinforcement, etc.
Beam-column elements: The program offers a wide range
of support modelling options such as liners, anchors and geotextile.
The beam -column elements in either Bernoulli or Timoshenko theory are
incorporated in the code and enabled the user to create complex finite
element models in which both plane and line elements interact each
other. Liner elements can be used in the modelling of tunnel lining or
sheeting structures. Bolt types include end anchored or fully bonded.
These elements can be assigned anywhere in the mesh.
Steady state flow analysis: The program includes the
steady state flow analysis built right into the general program. Water
pore pressures are determined as well as flow and gradient based on
user defined hydraulic boundary conditions and material permeability.
The water pore pressures are automatically incorporated into the finite
element stress analysis.
Dynamic and seismic analysis: The program allows the
users to carry out a dynamic analysis for determining the eigen values
and eigen mode for construction and consequently to determine the
seismic forces according with Eurocode 8.
Elasto-plastic material models: The present release
offers the following models: Mohr- Coulomb and Von-Misses models for
elasto-plastic behavior of plane elements. Both models are robust and
simple non-linear models and are based on soil parameters that are well
known in engineering practice. Both anchored and geotextile elements
could have either a linear elastic or elasto-plastic behaviour.
Ballistic impact in composite materials
Research developed at DEC, Faculdade de Ciencias e Tecnologia,
supported by contract 43228/EME/2001 with Fundacao para a Ciencia e
Tecnologia. (Silva MA, Cismasiu C, Chiorean C.G) Cooperation with
colleagues from INEGI, Porto and Comd. F. Neto from Navy School of
Lisbon is gratefully acknowledged)
A combined numerical and experimental study for the analysis of
Ceramic/Kevlar 29 composite armour system against 4.0g NATO 5.56 mm
calibre bullet has been invetigated. Ballistic impact was imparted with
simulated fragments designed in accordance with STANAG-2920 on plates
of different thickness. In all cases the projectiles impacted
orthogonal to the target and the ceramic tile is not bonded to the
ballistic performance of the lightweight armour systems was examined to
obtain an estimate for the V50 and the global damage of the composite
plates. All estimates were performed by varying the thickness of
ceramic tiles, while maintaining equal areal density of the system.
Simulation predictions and trial results is demonstrated both in terms
of deformation and damage of the laminates and ballistic performance.
Numerical modelling was developed and used to obtain an estimate for
the limit perforation velocity V50 and simulate failure modes and
damage. Computations were carried out using a commercial code based on
finite differences and values obtained are compared with the
experimental data to evaluate the performance of the simulation. Good
correlation between computational simulation and experimental results
was achieved, both in terms of deformation and damage of the laminates.
Silva, M.A.G., Cismasiu, C., Chiorean, C.G., Low
velocity impact on laminates reinforced with Polyethylene and Aramidic
fibres. In V.P. Iu, L.N. Lamas, Y.-P. Li, and K.M. Mok, editors, Computational Methods in Engineering and Science.
Proceedings of the 9th International Conference EPMESC IX, pp. 843-849,
Macao, China, 25-28 November 2003. A.A.Balkema Publishers.