|
The
structural analysis of slabs is carried out by the
finite elements method (FEM). The finite elements
consist of rectangular slab pieces having 4 nodes
and a degree of freedom of 12. Loads can be
defined as point load on nods, or as linear load
between two nods ,or as uniform distributed load
on slab. It is possible to define these loads in
any phase of the project on the slab.
The
user can determine in the slab setting dialog box
the finite element width of each slab.
The
slabs are then divided up into finite elements of
such width as determined. The nods formed at the
corner points of the finite elements are numbered
by the program automatically. Now the geometrical
characteristics and the loads of the rectangular
finite elements are determined. The program solves
the equations of the system and calculates the
displacements of the nodes, and the end forces. |
|
In
order to determine the design moments to be used
for the calculation of the reinforcement, the
relevant concrete calculation lines of finite
elements are defined by the program automatically.
At rectangular slabs the maximum values of the
moments are mostly in the middle of the slab. For
such slabs the concrete calculation lines are
automatically defined by the program in the middle
of the slab as soon as the slab is defined as
such. For polygonal slabs or for slabs with
irregular edges, the most appropriate concrete
calculation line can be calculated by ascertaining
the most critical areas of the respective slab by
examining the slab forces obtained from structural
analysis using several concrete calculation lines.
The user can define several concrete calculation
lines on one and the same slab, which are then
numbered automatically by the program. On the plan
the concrete calculation lines are represented by
consecutively numbered lines. For example for a
slab on which 4 different concrete calculation
lines are defined, a total 4 lines will appear
which are numbered consecutively as 1.2.3.4.
The
program detects automatically whether the slabs
are continuous one or simple supported, and how
their bearing, supporting and boundary conditions
are. At the edges of the slabs there can be any
beams, walls, shear walls or columns, or the slab
have free-ends. However one or more or even all
edges of the slabs can be hinged supported. If
there are any columns or shear walls at the edges
of the slabs, the program always assumes that the
slabs as supported with fixed-ends. But, if there
is a beam at the edges of the respective slab, the
program assumes such slabs as simple supported if
such slab is not non-continuous one, and as
supported with fixed-ends if it is a continuous
slab.
Each
slab is evaluated automatically and separately
depending on its individual supporting and
boundary conditions. For the supporting and
boundary conditions of the slabs, there are no
restrictions or limitations in the program. Also,
any mixed supporting is allowed, and any slab can
have n corners. Any in one way or in two way
working floor slabs, balcony slabs, landings or
eave slabs can be analyzed with the program easily
and independently of their geometry and supporting
(boundary) conditions.
|
|
As
soon as a concrete calculation line is defined for
a slab, the program determines automatically the
working style of the slab, and the type and the
arrangement of the reinforcement to be inserted in
accordance with the respective working style of
such slab. But nevertheless, for special cases,
the user is enabled to intervene in the working
style of the slab, and in the type and arrangement
of the reinforcement.
|
|
Below
are given the working styles of slabs and types and
arrangements of reinforcements as ascertained
depending on the relevant concrete calculation
lines:
The
program analyzes the following systems by the finite
elements method :
Slabs
working one way or two way
Mushrooms
(flat slabs)
Raft
foundations with or without strips
Single
footings
|
