FAQ’s PT

Can I create a DWG or DXF file for tendon or model geometry?
Yes, the program willl automatically generate a temporary file called “buildsum.dxf” when you generate a summary sheet of the envelope or load combination.  The file is located in  C:\Program Files\ADAPT\ADAPT-PT 2010\buildsum.exe.  Note that when you close the summary sheet, the file is automatically removed from this location.  Below is an example. 
Does the program consider pattern live loading for deflections?
No, if the user has set the program to consider patterned live load, the program will only consider the solution for fully-applied live load for deflection calculations.  For the design of sections and check of stresses, the program will consider the max and min envelopes from pattern live loading.  A scenerio could exist where the stresses reported may be greater than modulus of rupture (7.5 sqrt f’c) but the deflections are still based on gross properties if the moments calculated from fully-applied live load are less than the cracking moment.
What Live Load skip patterns does ADAPT-PT use?
Does ADAPT-PT check ACI 318-08 provisions 11.5.5.3?
Yes, the program checks all applicable code provisions relative to one-way shear for prestressed and non-prestressed systems.  The program will report **** when the maximum factored shear resistance, Vn, is exceeded.  The following technical note outlines the procedure for shear design in ADAPT-PT and Builder.
 
Do the assumptions made between unbonded tendon systems and the “Effective Force” method apply for bonded tendons as well?
The effective force assumption for post-tensioned tendons has been the primary method of design in North America for many years. Both ACI and PTI have been discouraging its use in favor of using the “Variable Force” method, but the practice is still common. The method applies to both bonded and unbonded systems. The application of the method is tied to a maximum tendon length for stressing. For unbonded tendons the practice is to limit the length to 38m (125 ft). For bonded tendons, this length is shorter. The practice is to select 33 to 35m (100 -115 ft) as maximum length. The shorter length for bonded tendons is due to a greater friction loss, which impacts the in-service performance for cracking and deflection. This, however, is compensated in part in greater increase in stress of bonded tendons at ultimate limit state.
 
 
What is the proper way to model a drop cap/panel at a corner of slab?  If the drop cap/panel extends beyond the slab edge, will it be considered properly in the Punching Shear check?
The program will correctly check the punching shear for either scenario (see image below) inside the drop panel/cap depth, however the check outside the face of the slab is checked differently in each case.  Outside the slab, for the condition where the cap/panel is centered on the column and extends outside the slab on two sides, the program uses the entire drop width in determining the critical sections (b1 and b2).  This results in allowable concrete shear stress values that are greater than actual.  In the second case, the program uses the entire drop width also, but the width is reduced to only account for that portion inside the slab boundary.  This is the proper way to model the condition.  The same can be applied to “End” and “Edge” conditions.
 
Why don’t the deflections in the graphical report match those in the tabular report?

The difference between the tabular and graphical report for deflection in ADAPT-PT is due to the creep factor used for the long-term deflection.  The total deflection in the tabular report indicates long-term deflection and will be calculated by:

 Total = (SW+SDL+PT)*(1+C.F.) + LL + XL

The results shown graphically do not include the creep factor and would be calculated by:

Service (Max) = SW+SDL+PT+LL MAX+XL
Service (Min) = SW+SDL+PT+LL MIN+XL

 The individual deflections in the cases above can be taken from each individual deflection graph.  These are the same values if you take successive load stages in the tabular report and subtract one from the other.  For example, to extract the SDL deflection from the report you would take:

(SW+PT+SDL) – (SW+PT) = SDL deflection. 
This is what is reported on the graph for individual deflection results. 

What is the most effective shape for post-tensioning cables in a cantilevered condition?
The distribution of loads on the cantilever will affect the response of the beam/slab to the post-tensioning, however, in general, Cantilever Down, Cantilever Up and Straight shapes located above the centroidal axis are often used.  One will find that when using a Cantilever Down shape, the amount of positive moment generated causing compression on top/tension on bottom is slightly more at each successive design section, since the location from centroid to CGS of PT steel is slightly greater.  Refer to the “Product Videos” page for ADAPT-Builder for an example of different shapes. 

Why don’t the stresses (Left/Center/Right) in the Recycler match the stresses in the tabular output?
The stress values reported in the Recycler Window are the maximum (tension or compression) values within the given location of the each span.  The values in the tabular report are those exactly at the supports and mid-span regardless of whether they are the worst-case or not. 

Why is the default CGS value for exterior spans set to 1.75″ as compared to 1″ when ACI is used?
If exterior spans are considered “unrestrained,” with respect to fire resistivity, they require a higher cover.

Does ADAPT-PT check punching shear at columns when a two-way slab includes transverse beams?
Yes, ADAPT-PT considers transverse beams similar to drop panels and drop caps.  If the transverse beam does not meet the necessary code-stipulated geometry requirements, the punching shear check will be carried out with respect to the slab geometry.  In reality, punching shear of columns that are in the vicinity of transverse beams are not typically a design consideration.  Our recommendation would be to simply disregard the output in these circumstances.  Note that ADAPT-Floor Pro does not check punching when a beam is connected to a column. 

In checking punching shear in ADAPT-PT, does the program use a minimum effective depth, ‘d,’  of 0.8h?
No, the program uses the centroid of the reinforcement (mild and PT steel) for the effective depth.  The code, ACI 318-05, specifically says that 0.8h limit is for the provisions of section 11.4 which is for one-way shear design. For other cases general notations will apply (See definitions in Section 2 of the code).

When I open a file in PT 2010 that was created in PT7 or PT8 and select to review results like moments, shears or Report Setup, I receive the error “No results available.  Please execute analysis first.”  Why am I receiving this error?
ADAPT-PT 2010 has a different file structure than the two previous versions.  When a .adb file is opened in PT 2010, the program will automatically create a sub-folder titled the same name as the file.  This sub-folder contains all intermediate files.  

If you open a file created in PT8, the program looks for files in a location where they are not found due to the file structure for PT8.  To overcome this you must do one of the following:

1. Rerun the analysis and the program will create new intermediate files.
2.  Open the .adb file in PT 2010 and then move all intermediate files from the PT8 run into the new folder created for PT 2010.

For beam design, does the program use full flange tributary when calculating minimum reinforcement as set forth in ACI-318 Section 18.9.2?
ADAPT-PT8 and PT 2010 base the calculation of minimum reinforcment on the section properties associated with the effective flange as calculated from ACI-318 Section 8.10.  The following scenerios apply:

1.  If effective flange is NOT considered, and Bf is greater than Beff, the program internally calculates Beff and uses this for the calculation. 

2. If effective flange is considered and the user allows the program to calculate Beff based on ACI-318, the program uses Beff for the calculation.

3. If effective flange is considered and the user sets the user-defined Beff value greater than the calculated value from ACI-318, the program uses the calculated value.

4. If effective flange is considered and the user sets the user-defined Beff value less than the calculated value from ACI-318, the program uses the user-defined value. 

Note that for determination of actions, stresses, etc., the program will use section properties associated with the calculated Beff unless user-defined input is selected. 

Why is my input screen cut-off at the bottom of the PT window?
The extent of the “Structure View” controls the location of each input screen as a user moves through the input wizard.  If the structure view window has been extended it will push the input screen below the level of the main screen, making some of the windows cut-off.  The default position of the input window is to be at the bottom of the structure view window.  To overcome this, the user must shrink the structure view window, click “Next,” and the input windows will be repositioned below the structure view window.

Are lateral load results included for one-way shear design in ADAPT-PT?  
Yes, ADAPT-PT considers shear results from all user-defined “Strength” and “Lateral” load combinations.  The program determines the worst-case stress ratio (Vu/PhiVc) at each design section.  Each combination, as referenced above, is evaluated using Section 11.4.1 and 11.4.2 of ACI 318.  The output results (Section 12 of Report Generator) show ONLY the design values associated with the worst-case ratio.  The user can also review results for each individual load combination by reviewing the sub-file, “STRUPRC_det.DAT.”  This file is located in the directory selected by the user where model files are stored. 

 

Why are my results different when I compare a design strip in Floor Pro and PT?  
When comparing results between the two programs, there are several things to consider in order to make an adequate comparison.

-Make sure that the load combinations include Prestressing or Hyperstatic actions.  If you open a project in ADAPT-Floor Pro RC and later open in Floor Pro PT, the auto-generated load combinations from RC will remain.  These do not include prestressing effects.  To include prestressing, you can modify the combinations manually or you can go to CRITERIA>General>Analysis/Design options and toggle between codes.  This will auto-generate the combinations and include the prestressing effects.   

-When you import tendons from ADAPT-PT, they are automatically “disregarded” in the FEM analysis.  To include the PT in the design, you must click on each tendon that has been imported and in the FEM tab, change from “Disregard” to “Consider.”  You can also do this for all tendons by selecting all tendons and using the MODIFY ITEM PROPERTIES tab.  On the left hand side you will see FEM and here you can also change to “Consider.”

 -Make sure that the design criteria and other variables match in the Floor Pro and PT.  Note that for Loading, Material and Criteria input there are options for both FEM and Strip Method.  If the results are to compared, make sure that the design parameters are similar for each model. 

-Results between Floor Pro and PT will not be exactly the same for such a structure, regardless of having identical input parameters.    The analysis methods are different (FEM vs. Equivalent Frame Method) and variation in results is to be expected since in one method (EFM) general approximations are used in equating a 2D frame to exhibit some two-way slab action through torsional members.

Is it possible to run PT v7 and PT v8 on the same computer?
No, we recommend that you would uninstall PT v7 and then install PT v8.
 Is PT v8.00 backwards compatible with older versions of PT
For versions 6.xx or 7.xx – yes
Yes, you can open your old files and solutions from v6.xx or v7.xx in PT v8.00 and all your input data including geometry, loading, design code selection etc. will be available.

In the Support Geometry and Stiffness input screen, what is the meaning of Left Edge and Right Edge?
Left edge and Right edge is used to categorize the supports for the punching shear calculation. Left edge is the edge of the left tributary of the support and right edge is the edge of the right tributary of the support.
If you select interior for both, the program will consider that support as interior for the punching shear check even if the support is exterior by geometry. If you select exterior, the support categorization will be based on the geometry and the code requirement.

How is the length of rebar calculated?
The PT program divides each span into 20 design sections and checks for and provides rebar if required up to the end of each section plus one additional full design section beyond that. So even though theoretically the rebar requirement might cease somewhere within this last design section, the rebar is extended to the end of that design section. This is a conservative approach.
So the length of the rebar is the length between the ends of these design sections plus the extension length you entered in the “Criteria-Minimum Bar Extension” input screen, if the rebar is from the strength case.
Minimum rebar is provided based on the user’s selection in the “Criteria-Minimum Bar Extension” input screen, and the default is 1/3 of the span length in positive moment regions and 1/6 of the span length on either side of support in the negative moment regions. Regardless of the load cases, the program conservatively considers one section beyond which requires reinforcement.

After selecting my report content, can I save the selection as a template for other models?
Yes, this is possible. You can save the content as default report content or you can provide any other name for your selection and use it as a template for any project.
If I have multiple spans with the same loading, do I have to enter the load individually for each span?
Certainly not. You can enter the loading by simply using one line in the Loads input screen. Enter “all” into the “Span” cell, select the appropriate class and load type. After entering the necessary load information, e.g. “w” for uniform load or “a” and “F” for concentrated load, the loading information is applied for all spans.
Once you go to the next input screen and come back to the Loads input screen, the loading information is distributed in the table for all the spans.

Why do my column layers have different forces for punching shear check?
If there is more than one strength load combination, the program checks punching shear for each layer for each load combination and reports the forces for the worst case ratio. Therefore, it is possible to have different forces for each of the layers.

Why are the options for ‘I’ section and extended ‘T’ section grayed out?
If you are trying to use either of these sections for the design of a flanged beam, make sure you turn off the consideration for effective flange.  This wil allow either of these sections to be active.

Why is my reinforcing output so much even though i have transverse beams?
The program does not include the depth of transverse beams in calculating reinforcement for strength unless the beam meets the code requirements for geometry of L/6 to each side of centerline. 

Why are the “I/L” and “Extended T” sections not avaible for beam design?
To activate these sections, select “No” to consider effective flange.

Which calculations use the section properties based on effective flange width?
The calculation of flexural stresses uses Beff.  The program reports precompression as a function of the full tributary width.