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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
     - Windows 98 and over
     - XGA  1024x786 screen card 64mb
     - Microsoft adopted Mouse
-Windows adopted print 

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.
 

 

 

 

 
   
 
   
 
   

 
 
   
 
 

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.
 

C-CALCULATING WIDTHS OF T-BEAMS  (TS 500)
 

 
 
 
 
   
 
   
 
 

D-CALCULATING TORSIONAL FACTORS OF COLUMNS AND FLOORS
 

 
 
 
 
   

E - STIFFNESS  MATRICES OF BEAM ELEMENTS
 

 
 
 
 
     
 
   
 
 

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.
 

 
 
 
 
     
 
   

G- BASIC STIFFNESSES OF BEAMS THAT ARE ON ELASTIC GROUND
 

 
 
 
 
     
 
   
 
   
 
 

TRANSFORMATION OF LOCAL STIFFNESS MATRICES OF BEAMS TO GLOBAL STIFFNESS MATRICES OF BEAMS
Transformation matrix of a beam element in xy plane
 

 
 
 
 
     
 
   

I-CALCULATING FIXED END VALUES OF BEAMS

Loads, which are applied to parts of beams that remain in columns, are transferred directly to columns and stiffness values of beams are found due to moment-area theory by assuming that beams are rigid in beam-column intersection region. In accordance with this, fixed end moments of beams are calculated according to axes that remain out of column widths. These fixed end values are again transferred to column axis. Especially if in beams with wide supports real fixed end moments are not calculated in that way , great differences can occur.
 

 
 
 
 
   
 
   
   
 
 
 

J-TRANSFERRING LOADS ON FRONT ENDS OF BEAMS TO GLOBAL AXES
 

 
 
 
 
     
 
     
 
   
 
 

K- TRANSFERRING RESULTANT GLOBAL END MOMENTS OF BEAMS,
      OF WHICH DEFLECTIONS ARE CALCULATED, TO LOCAL AXES
 

 
 
 
 
     
 
   

L-  ESTABLISHING STIFFNESS MATRICES OF COLUMNS

a) Finding moments of inertia of columns
 

 
 
 
 
   
 
 
 
 

b) Basic Stiffnesses of Columns and Shear Walls
 

 
 
 
 
   
 
   
 
 
 
 

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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This site was last updated 08/05/10