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STA4-CAD PROGRAMME
Version 13.1
INTRODUCTION:
STA4 programme is a software package which analyses
multi-story reinforced concrete structures due to static,
earthquake, and wind loads concurrently. The programme makes
static and reinforced concrete analyses in accordance with standards
and codes. If the codes are changed or international standards
are to be applied, the user .can change
many of the parameters
The statical analysis method used
is Stiffness Method. In 12.0 Version, which makes 3-dimensional
analyses, structural equilibrium equations for finding dx, dy ve qz
deflections of storey plan are constituted by assuming that slabs in
horizontal direction have infinite rigidity. Therefore, by the
assumptions of qz, dx, dy deflections in floors and dz, qx, qy
deflections at end points of elements, equilibrium equations of the
whole structure are constituted. The programme makes structural
modelling automatically by defining structural data as plan
application input. It also constitutes and solves equilibrium
equations at once by considering rigidity of elements. Furthermore,
it finds real effects in statical analyses of structure and
determines effects of soil collapses and rotations in rigid upper
part of structure, taking into account structure-soil interaction.
Since static analyses are 3-dimensional, it analyses grid or
irregular beams in plan as finite elements and evaluates the results
as a single beam
The programme makes analyses by using 16 loading conditions which
use the most unfavorable load combinations in structure. These are 7
vertical load combinations (dead load, live load, checkered, band
combinations), 4 earthquake or dynamic analysis combinations (in x
and y directions, and by assuming ±%5 deflection of gravity center
of structure), 4 wind combinations (in x and y directions, and
by assuming ±%5 deflection of gravity center of structure), and 1
combination which is related with static load-bearing capacity of
structure due to effect of soil
Structure modelling determines relationship of unit of measurement,
loads, and elements accurately in irregular structures since
elements are rigid and load distributions on floors are vectoral.
Mostly used element types in structures are considered. Beams, which
have smooth, prizmatic, haunced, and variable sections or which rest
on wide shear walls, are taken into account in stiffness and load
matrices
Rectangular, prizmatic, circular and irregular (polygonal ) columns
are separately defined. Stiffness values in column static analysis
rigidities are arranged by checking shear walls for shear
deformations. Floors which are irregular, ribbed, and formed of
rectangles in large numbers are considered. Footings are analysed
both with and without interaction of structure, due to finite beam
theory (Winkler Hypothesis) which takes into account soil behaviour
Earthquake calculations are made due to both earthquake code
(equivalency method) and modal superposition (modal analysis).
Dynamic soil speed spectra for different regions exist in programme
library and can be changed by the user or new spectral values can be
defined
Reinforced concrete section calculations are made due to elastic or
ultimate strain method in accordance with TS 500. Ultimate capacity
is evaluated due to earthquake, deflection and ductility conditions
The programme makes reinforced concrete calculations by column
moment increasing factor due to column and floor torsions
In programming, easiness of entering data input is as much
important as soundness of scientific basis of theoretical principles
of programme. Entering data input by a fast editor, which has a low
error making frequency, and seeing floor plan on graphical screen in
proportion with entered input provide the user with easiness in
using the programme
Input definiton of STA4 programme is prepared by floor application
principle. Entering data input for every floor is seperate. Similar
data betweeen floors, in floors, and in symmetrical structures can
be easily copied, thus whole structure can be formed by a very
little data input. Data, which is entered completely in graphical
environment and by the help of mouse, can be seen graphically. Data
keys and intelligent user menu, which brings keyboard usage to a
minimum, can be used. Data can be transferred easily since 65 keys
can be controlled at the same time
Analysis of results, optimization and arrangement of bars can be
observed visually on graphical screen. Since printer is mostly
graphical in new version, output is sent directly to printer. Output
can also be optionally taken as graphical output. Drawings can be
taken automatically since input is defined by floor plan principle.
Data can be arranged interactively in drawings. Moreover,
correcting, erasing, defining units of measurement, adding functions
can be easily applied on drawings, which are automatically produced
by the programme, by using the drawing editor
Reinforced concrete structures, whose analyses consume too much
time and money, can now be designed economically by making use of
computer technology. Since static and reinforced concrete
calculations are made by computer, engineer has enough time to spend
on structural modelling which is of high importance. Although
structural modelling depends on experience, different structural
models can be formed easily by the help of computer programmes that
serve for right goals and depend on sound theoretical fundementals
STA4 programme is prepared for orthogonal and nonorthogonal
structures, for example houses, commercial buildings,etc., shifted
floors, and stepped structures. Vertically inclined elements are not
considered. STA4 programme has been developed from 1976 to 2005 by
practice. Its theoretical principles depend on international
scientific theories and its usage is very practical. It is first
prepared by Fortran IV, then developed by PDS+Assembler language.
Its 12 .0 version is completely Windows adopted
Minimum
computer configuration for STA4 programme
- Pentium IV and over
- Min. 254 Mb RAM
- Min. 4 GB Hard Disc
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Windows 98 and over
- XGA 1024x786
screen card 64mb
- Microsoft adopted
Mouse
-Windows adopted print
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B -LOAD COMBINATONS FOR
STRUCTURE
Horizontal Load
Combinations
These loads include soil effects on structure
at floor level in both directions and are multiplied by
dead load factors. As indicated in earthquake
code, eccentricity, minimum ±%5 of height of
building, must be added. Torsional moments of floors are
calculated in accordance with this obligation. Since
live load's effect is between %30 and %80 in earthquake
and gravity center of live load is eccentric, two
seperate loadings are made in the same direction.
In
the same way, 13, 14, 15, 16 loadings are also
considered torsional for wind calculations. Load center
of wind is considered to act on average lateral area of
respective floor. Similarly, eccentricity, minimum %5 of
height of building, of this point is calculated and
torsion of respective floor due to wind is
found.
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Dead, live, and horizontal loads on structure are
put in equilibrium equations before they are multiplied
by characteristic load factors. According to reinforced
concrete analysis option, they are multiplied by these
factors in order to find maximum unfavorable
values.
Load Combinations Essential For Finding
Maximum Effects
a) Characteristic load values
entered in optional part of the programme;
fg :
Characteristic dead load factor (1.4)
fq :
Characteristic live load factor (1.6)
fE :
Characteristic earthquake load factor (1.0)
Fw :
Characteristic wind load factor (1.3)
b)
Load combinations due to ultimate capacity
option;
Cg x G + Cq x Q
> 1.4 x G + 1.6 x Q
G + Q + Cd x
E > G
+ Q + E
0.9 x G + Cd x E
> 0.9 x G + E
G + Q + Cw x
W > G + Q + 1.3 x
W
0.9 x G + Cw x W > 0.9 x
G + 1.3 x W
c) Load combinations due to
elastic strain option;
(Attention: not
in accordance with 1997 Earthquake Code)
G + Q
(G
+ Q + E) / 1.33
(G + Q + W) / 1.25
Since
footings are assumed to rest on elastic soil and
analysed by finite beam theory, nominal loads are
considered in static analysis. Soil strain is checked
according to elastic strain load combination. But in
reinforced concrete analysis, load combination that is
convenient for analysis option is
considered.
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C-CALCULATING WIDTHS OF T-BEAMS (TS
500)
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D-CALCULATING TORSIONAL FACTORS OF COLUMNS AND
FLOORS
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E - STIFFNESS MATRICES OF BEAM
ELEMENTS
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F - BASIC STIFFNESSES OF
BEAMS
AI, AJ, BIJ
values are calculated by dividing the beam into 200
parts, performing numeric integration in accordance with
moment-area theory, and considering wide supports and
haunches.
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L- ESTABLISHING STIFFNESS MATRICES OF
COLUMNS
a) Finding moments of inertia of
columns
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b) Basic Stiffnesses of Columns and Shear
Walls
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Especially if dimensions of polygonal columns and
shear walls are same, effects of shear deformations are
expected to be great. Therefore, in STA4 programme
stiffness coefficients of polygons are formed in local
axes of polygon. Effects of shear deformations are
calculated according to these axes and then they are
transferred to
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