STRUCTURAL CONCRETE
DESIGN 
DETAILS  
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The
RAPT analysis and design package for reinforced and posttensioned
concrete structural systems has been written and developed by practising
structural engineers as an everyday design tool.
It is comprehensive in its treatment of the analysis and design of
structural concrete. RAPT
is developed for use with IBM compatible personal computers, and will
perform design and analysis to the following National concrete design
standards:


The
following design utilities are incorporated in RAPT:

The
input is fully interactive using spreadsheet format.
Typical design parameters are defaulted where relevant.
The emphasis is placed on minimizing laborious data entry, and
providing maximum flexibility in design options.
Program execution proceeds interactively, progressing through the
design sequence, showing all steps normally taken in standard design
office procedures.  
RAPT
and PARTIALLY PRESTRESSED CONCRETE DESIGN In
RAPT an integrated approach to reinforced and posttensioned design is
adopted, consistent with the concept of partial
prestressing. Fully
prestressed design specifies that a minimum compressive stress exists in
the concrete under all service conditions.
That is, the concrete is at no time cracked or subject to tensile
stresses. In
contrast, partial prestressing requires that structural elements comply
with design limit states of ultimate
strength and serviceability (as
with reinforced concrete). This
rational basis for design is in accordance with the philosophy adopted in
modern design codes, in which reinforced concrete design and design for
full prestress represent the two extremes of structural concrete design.  
GENERAL
CONCRETE MEMBERS RAPT analyses and designs a subframe consisting of the member to be designed with columns above and below. Nonprismatic concrete members with multiple concrete layers and voids can be defined using a series of trapezoidal and circular concrete shapes to define basically any concrete crosssection and elevation.
CONCRETE FLOOR SYSTEMS RAPT
will design the following floor systems: 
Flat Slab/Flat Plate. 
Beam and Slab. (1 or 2 way). 
Slab and Band systems.  Beam systems, transfer beams etc.  Columns of any shape  
RAPT MEMBER DESIGN TECHNICAL DESIGN FEATURES  

These floor systems can include any of the following standard concrete element types 
slab of variable depth 
drop panels 
drop caps 
beams/bands (upturn and/or downturn) 
rectangular/circular columns 
extra concrete layers 
vertical steps in all horizontal surfaces 
horizontal steps in all vertical surfaces 
sloping surfaces in all surfaces 
solid and void rectangular or circular elements These last 5 options allow the designer to define members with complex shapes with virtually unlimited variations in crosssection shape if necessary while maintaining a simple method to define normal members with little shape variation. Construction for any of these floor systems may be conventional reinforced, partially or fully prestressed concrete (bonded or unbonded), pretensioned. 

LOADING RAPT creates primary load cases to allow for 
self weight loads 
superimposed dead loads 
live loads (envelope) 
wind loads (envelope)  earthquake loads (envelope)  moving loads Extra load cases
can be added by the user to handle more complicated loading arrangements.
These primary load cases can include combinations of the following load
types 
uniform distributed loads 
linear distributed loads 
trapezoidal distributed loads (partial length of member) 
point loads 
point moments Alternate/Adjacent span pattern loads are automatically generated by RAPT from the live load primary case if requested. Combinations of these primary load cases are defined by RAPT to create envelopes of design moments and shears for design purposes. For standard primary load cases, RAPT adds the primary load cases to the appropriate combinations with multiplying factors for the design code being used. Extra load cases are added to combinations with factors defined by the designer. Designers can override the combinations created by RAPT or create extra combinations if desired.


PRESTRESS Tendon profiling may
be automatic, semiautomatic or fully manual allowing several different
profiles in any given run. Tendons may start and end at any user
defined location along the member, thus allowing the definition of
different tendons between pour strips for large floor slabs to correctly
model the tendon forces. At a crosssection, different tendons may be at different heights and have different prestress forces. Tendons are not required to extend over the full length of the member. Some sections can be plain reinforced concrete while other sections are prestressed. Tendon Profiles can be 
straight 
parabolic (with or without straight portions) 
single point load 
double point load. All prestress loss calculations are carried out automatically, followed by a complete equivalent load analysis, removing a majority of the time consuming computation associated with these aspects of prestressed concrete design. Secondary (hyperstatic) prestress effects are calculated automatically and are fully incorporated in the analysis and design. The designer can control the use of these in the load combinations. REINFORCEMENT The
designer can specify different cover zones in different areas of the
member. The
designer can specify simple or complex reinforcing patterns in the input
to be checked for capacity and their effect on ductility, shear and
deflections. RAPT automatically allows for end development of defined reinforcement depending on the location of a design crosssection from the bar end. 

MEMBER ANALYSIS AND DESIGN Member/joint
layouts and Frame properties are calculated automatically from the member
shapes defined in the input. Modelling of columns may use either full
column stiffness or the equivalent column approach and incorporate column
shortening and various restraint effects. RAPT executes a
stiffness analysis for all loads on the structure and combines them for
transfer, service, ultimate and several deflection conditions using
combinations specified in the relevant codes, or any user defined set of
combinations. Structural
actions are automatically distributed in twoway systems. Designers can
control the distribution factors if desired RAPT
automatically determines the points at which design checks are performed
and includes all critical points in the frame 
critical section at support

changes in section 
ends of prestress tendons 
reinforcing bars 
plus at intermediate points to
provide the designer with the distribution of reinforcement required in
the member 

Detailed reports are given at all design points (min 13 per span) 
moments and shears  reinforcement areas  stress conditions  deflections  shear reinforcement 
reinforcement spacings and bar numbers 

ULTIMATE CAPACITY Ultimate strength checks are performed for both primary and reversal moments at all points and include checks for  existing capacity (tendons and reinforcement)  minimum reinforcement  ductility (including determining of plastic hinge locations)  extra reinforcement requirements for ultimate strength A detailed concrete stressstrain relation is used in a moment curvature analysis to accurately analyse any crosssection configuration 

SERVICE CAPACITY Service stress checks are performed for both primary and reversal moments at all points. Transfer stress checks are performed for both primary and reversal moments at all points. A complete cracked section analysis is performed if any section is subject to tension under working or transfer loads. The cracked section results include the tabulation of the stresses in the concrete and steel layers. Reinforcement will be added to control cracking if necessary and requested by the designer. Crack Control calculations are performed automatically in different ways depending on the system type and design code. 
SHEAR CAPACITY Beam and punching shear are investigated for each
span and column respectively, with complete design of shear reinforcement
and spacing checks for each of the ultimate load combinations and also for
the reversal case. The controlling case
is reported at each design section. Shear
enhancement calculations are performed if allowed by the design code
(BS8110, CP65, SABS0100, AS3600).  

DEFLECTIONS Deflections are
calculated for 4 load stages to allow for transfer, short term, permanent
loading and initial loading stages using Moment Curvature principles.
The four deflections calculated are 
transfer (self weight) 
short term 
long term 
incremental Deflection calculations allow for 
cracking 
tension stiffening 
creep  shrinkage warping  time of loading  reinforcement layouts  load history. Creep, shrinkage and tension stiffening are considered in a detailed, advanced analysis of the member which determines their effect on the curvature and deflection of the member at different loading stages. Effects of tension and compression reinforcement on deflections are allowed for in the calculation of member curvature which considers loading and creep, where appropriate, and shrinkage warping. For twoway systems, deflections are calculated for both column and middle strips. 
RAPT
represents a continuing trend towards increasingly comprehensive analysis
and design software. The
traditional approach of iterative and distinct phases of analysis and
design is considerably enhanced. The
design process is reduced in its duration and complexity by the
interaction of the designer at various stages of design and analysis, the
minimization of superfluous data entry by employing default
parameters, and the ability to selectively automate
those components of the design process that are repetitive and time
consuming. These
elements of design are integrated in the one package, eliminating
discontinuities and incompatibilities existing between both analysis and
design software, and reinforced and prestressed design. Future
editions of RAPT will further develop these aspects with design detailing
output in plan and section form.  

COLUMN
DESIGN RAPT's
column design utility offers designers complete flexibility in defining
complex column (bending and compression member) shapes and reinforcement
patterns. Special
features include  Simple column generator for circular and rectangular columns and reinforcement patterns 
Complex column shapes built from a range of solid and void
rectangular, trapezoidal and circular quadrant shapes 
Complex reinforcement patterns to suit any column, bundled bars 
Prestressing steel patterns (pretensioned or posttensioned) 
Generate Single interaction curve with critical points defined 
Generate multiple interaction diagrams for range of bar sizes 
Tension zones included 
Compare design points graphically 
POSTTENSIONING THE ADVANTAGES The advantages of posttensioned concrete floor systems are well documented, and may be summarized:
In many instances partial prestressing represents the most economical and best performing structural solution.* * RAPT allows optimisation of a prestressed concrete solution with the ability to investigate a number of possible configurations to a high degree of accuracy very rapidly.  