1. Main Menu:  This menu allows for easy access to all program functions.  One can select the design or analysis mode, the type of geometry, and the reinforcing material.  Input data and various stability runs are accessible by a click of a button.  Note that semi-complex geometry pertains to tiered slopes (up to 10 tiers) comprised of only three soils; input data for such system is quick compared with the complex option.

2. Input Data Menu for Simple Geometry: All parameters needed in the analysis mode are grouped into categories. Each group can be accessed individually.

3. Simple Geometry: ReSSA considers simple geometry as a slope having sloping toe, broken-back crest, and subjected to some surcharge loads.  The input data defining such a problem are quick; the drawing to the right adjusts automatically to the input data.

4. Strip Footing Surcharge:  This dialog allows for up to three different strip footings located on the crest.  This surcharge can represent loads such as footings, highway lanes loading, etc.

5. Phreatic Surface: Porewater pressure can be calculated utilizing a specified phreatic surface.  Data is input using a spreadsheet-like table.  As data is input, the drawing to the right is updated.  Porewater pressure is used in the effective analysis mode; it might be invoked also in mixed analysis.  If the phreatic surface is above the soil surface (i.e., pseudo phreatic surface), the effect of ponding water is considered as surcharge. 

6. Tensile Crack:  A crack with constant depth, starting at a specified distance from the toe and extending backwards, can be considered.  Such a feature is useful in case negative normal stresses develop near the crest (ReSSA calculates and displays the normal stress over the critical Bishop circle); introduction of a crack can alleviate negative stresses.

7. Soil Data:  In simple slopes, three soils are considered.  For each soil the user needs to input the unit weight, friction angle and cohesion.  It is recommended to limit the cohesion of the reinforced soil to zero in design.

8. Seismicity:  ReSSA conducts pseudostatic analysis considering horizontal ground acceleration.  The design acceleration is taken as half the maximum ground acceleration.  This is in lieu of perceived conservatism inherent in the pseudostatic approach; it also follows FHWA recommendations.

9. Reinforcement Choice:  To facilitate the input of data, the user can select one type of reinforcement (quickest input) or multiple types in the same slope (limited to five different types). Alternatively, an unreinforced problem can be specified.  

10. Geosynthetic Reinforcement: For single type reinforcement, the user can select reinforcement at fixed spacing and length (quickest).  Alternatively, the elevation and length of each layer can be input.  Furthermore, the ultimate strength, the corresponding reduction factors, the coverage ratio and the designated name, need to be input using the spreadsheet-like table or retrieved from a user-created database (ReSSA enables the user to create a database).   The relevant interaction parameters can be accessed from this dialog. Furthermore, up to 10 layers of reinforcement can be embedded below the user-defined "toe." This means that 10 layers can be embedded in the foundation soil to increase, for example, bearing capacity.

11. View Input Layout: By clicking on a button within the reinforcement dialog, the user can review the specified layout superimposed on the geometry of the problem.  This option provides a convenient visual mean that assists in reviewing the input data.

12. Interaction Parameters (geosynthetics): By clicking on a button within the reinforcement dialog, the user can access the dialog for input of data related to interface strength properties.  These values control the pullout resistance as well as resistance to direct sliding along the reinforcement. 

13. Front-end Strength:  ReSSA allows the user to specify available strength at the front-end of the reinforcement.  This strength, for example, may represent the connection strength of a particular facing element.  ReSSA calculates the strength away from the slope by adding the resistance developing along common interfaces with the soil.  The long-term specified strength and front-end or rear-end pullout, whichever is smaller, is used in analysis.  Note that the term front-end pullout signifies a situation in which the soil moves relative to the embedded reinforcement.  This parameter may control surficial stability. ReSSA can assess surficial stability if the search domain is properly specified.

14. Procedure of Calculating Direct Sliding:  ReSSA is using 2-part wedge mechanism combined with Spencer method to assess resistance to direct sliding.  As a result, effects of reinforcement strength can be considered.

15. Multiple Reinforcement:  Up to five types of reinforcement can be specified.  Data can be retrieved from a database or entered manually. 

16. Manual Input of Reinforcement:  Using the table as a spreadsheet, one can select the elevation, length, front-end strength and type of each layer of reinforcement.  The drawing to the right adjusts automatically as the data is input.

17. Specified Search Domain in Rotational Analysis:  The user need to input a range of likely starting points and exit points for potential slip circles.  The figure to the right shows the specified points at their respective location.  ReSSA considers all combinations of such points attempting to find the critical circle for each pair of points by internally examining all feasible circles through these points.

18. Results of Bishop Analysis:  The first screen appearing after running rotational analysis is shown.  It includes the trace of the critical slip surface (based on the specified search domain) as well as the corresponding factor of safety.  In case the search domain has not captured the absolute minimum, the user can redefine the domain and rerun the problem from this dialog.  This dialog also includes many relevant results related to the search or to the critical results.  The user can print the figure or save it as a bitmap file.

19. Fs Distribution:  Using the Bishop dialog menu (RESULTS), the user can select to view the distribution of minimal safety factors along the specified search domain (entry and exit points of circle).  Upon pointing the mouse on each vertical bar, the corresponding Fs is displayed at the bottom of the screen.  The display of this distribution is useful since it allows the user to confirm whether the minimum case was indeed captured.  This is particularly important in reinforced or complex slopes since there is a possibility for several local minima.  Also, the designer can get a sense how 'flat' is the minimum for a particular problem.  That is, it serves as a diagnostic tool.

20. Available Reinforcement Force:  By clicking on the numeral on the left of this dialog (each button corresponds to reinforcement layer), a graphical display of the distribution of long-term available strength along the respective reinforcement layer appears.  Also, the numerical long-term strength values appear at the upper left side.  

21. Display Analyzed Circles:  The user can retrieve a large sample of analyzed circles.  Superimposing the critical circle on the many analyzed circles indicates how well the critical circle falls within the search domain (i.e., is it on the edge of the search domain? are there unexplored gaps?)

22a. Display Effective Stress and Slices: Upon clicking on the DISPLAY menu in Bishop's results, the effective normal stress over the critical circle is displayed.  The slices and porewater pressure can be displayed as well.  This option can be useful in case tensile stresses tend to develop over the slip surface (quite common in cohesive soil).  In such a case, the user may introduce a tensile crack. Hence, a rational tool is provided to determine the depth of the tensile crack that is likely to develop so as to produce only compressive normal stresses .

22b. Safety Map: For a selected failure mechanism and specified increments of safety factors starting at the minimum, the user can display the distribution of safety factors within the soil mass. This display is a useful diagnostic tool in assessing the stability of reinforced or unreinforced slope. Click here to download a pdf file demonstrating the effectiveness of the safety map.

23. Search Domain for Translational Analysis:  Translational failure is defined by a 2-part wedge mechanism analyzed using Spencer method.  In this dialog the user can specify the search domain along each layer of reinforcement as well as the foundation interface.  In most cases, pressing the Default button will set a reasonable domain.

24. Results of Direct Sliding:  This dialog shows the critical 2-part wedge along a user-specified interface (by clicking on the numeral on the left side of the screen).  Also shown is the distribution of the factor of safety along the interface at the specified points in the search domain.  This distribution appears after clicking on the respective button in the RESULTS menu.

25. Display Effective Stress, Slices and Line-of-Thrust:  Upon clicking on the DISPLAY menu in Spencer's results, one can select to display the effective normal stress and the porewater pressure over the slip surface, the slices, and the line-of-thrust.  This line is important in judging the reasonableness of the results (it should be within the sliding mass).  The user can select to view these results along any analyzed interface.  In case the results are not reasonable, the user can rerun the problem for different surfaces.  Note that ReSSA uses the reinforcement force only at the slip surface and not at the interslice sides.  That is, since the internal force distribution along the reinforcement is not known (only the strength can be assessed), incorporation of such a distribution in the analysis requires some assumptions.  To avoid such assumptions, ReSSA deals with the strength value at the slip surface only.  The trade off can be a jump in the line-of-thrust whenever a reinforcement layer intersects the slip surface.  Tabulated results in the RESULTS menu allow for numerical assessment of such a situation.

26. Sample of Explored Surfaces:  By a click of a button the user can view a significant sample of the two-part wedges used in the minimization process.  This can assist in assessing the comprehensiveness of the specified search domain in relation to the identified critical surface.

27. Specified Search Domain for 3-Part Wedge: ReSSA is capable of conducting stability analysis for user-specified 3-part wedge using Spencer method.  The user needs to input grid points defining the boundaries between the active and central wedge and the passive and central wedge.  ReSSA will check all combinations between these two grids while changing the angles of the active and passive wedges to produce the critical surface.  As shown in the dialog, the user can review a large sample of the wedges to be analyzed and if needed, to adjust the specified search domain.

28. Results of 3-Part Wedge Analysis:  If a 3-part wedge intersects reinforcement layers, their effects on stability are included.  The user can view the critical surface captured by ReSSA, as well as the details of the calculations (shown are the slices used, the normal stress distribution over the surface and the line of thrust).  Such display allows for quick review of reasonableness of results.  Detailed tabulated results and Spencer numerical tolerance and theta can also be viewed. The user can display all examined slip surfaces. 

29. Metallic Reinforcement Input:  If metallic reinforcement is selected in the Main Menu, this dialog will appear in response to clicking on Reinforcement.  This dialog is suitable for metallic mat; however, it can be modified to deal with other types of metallic reinforcement.  Data can be typed directly or retrieved from a user-prepared database (database can prepared using ReSSA functions).

30. Corrosion Calculator:  This dialog is convenient for assessing the corroded area for a given lifespan assuming the soil is mildly corrosive. The result can be imported directly into the table characterizing the design properties of the reinforcement. 

31. Interaction Parameters:  The pullout parameters for metallic reinforcement depend on embedment depth (per AASHTO).  The user can use the default values or replace them with more appropriate values.   The parameters required to resist direct sliding are similar in nature to those for geosynthetics.

32. Semi-Complex Geometry:  The option for semi-complex geometry allows for quick input of data relative to the complex geometry.  It is limited to three types of soils (similar to simple geometry).  However, up to 10 tiers of reinforced and/or unreinforced slopes can be input quickly.  The user has to specify the height, offset and slope of each tier. 

33. Results for Rotational Stability of Semi-Complex Geometry: As is the case for simple or complex geometry, the results of Bishop analysis can be displayed in full details.  The critical slip circle, the slices, the normal stress distribution, and the distribution of Fs (in green) along all specified points of entry and exit of examined circles are shown . Such display allows for assessment of reasonableness of results and whether the absolute minimum Fs was captured.  All examined surfaces can be displayed by a click of a button. 

34. Results for Translational Stability of Semi-Complex Geometry: Here the critical two-part wedge representing direct sliding along Layer 2 is shown.  Note that the line of thrust and the normal stress distribution can also be displayed.  Furthermore, the critical surface for sliding along any reinforcement or the foundation interface can be displayed.  All the details of Spencer analysis results for each such surface can be retrieved.  All examined slip surfaces can be displayed. 

35. System Setup before Input of Complex Geometry:  Input of complex geometry can use mouse functions and may involve up to 25 different types of soil.  Using this dialog the user can select the scale of the drawing considering the potential extent of the problem.  Also, realistic elevations can be used in the plot.  Colors of the various soils can be selected from a large array of preset colors.  The sensitivity of the mouse can be set if the user prefers to draw the geometry of the problem rather than insert numbers into tables. 

36. User Defined Coordinates: The "red" rectangle represents the viewable area on a computer screen. Hence, the user can optimize the size and region of the displayed area by defining the coordinates .  It facilitates the input of the complex geometry. 

37. Input of Complex Geometry:  Each soil boundary can be described by up to 100 sections.  The elevation of each layer can either be typed into the table or inserted by using mouse functions (see above drawing area).  Soil properties for each layer are also input in this dialog.  The drawing adjusts to the input data automatically.

38. Results for Rotational Failure - Complex Geometry:  This dialog shows the screen appearing after running Bishop analysis and it includes the resulted distribution of Fs for the defined search domain.  This distribution is particularly important for complex geometries where several minima may exist.

39. Specifying Reinforcement in Design Mode:  Design mode in ReSSA is limited to simple geometry only.  For given factors of safety ReSSA should produce an approximate reinforcement layout (the search is limited to internally prescribed constraints; hence, the designer is prompted to switch to analysis after running the design mode to ascertain that safety and economics are met for the actual problem; upon such a switch, all data produced in design is retained and used in Analysis).   This dialog is similar to Analysis; however, it provides the user with an approximation for minimum suitable strength of reinforcement.

40. Target Factors of Safety:  Using this dialog, the designer can specify the minimum desired safety factors for the specified reinforcement (strength and spacing).  ReSSA will attempt to produce reinforcement length (only in simple geometry) that meets these target values.

41. Results of Bishop Analysis in Design Mode:  This dialog shows the resulted layout, based on rotational stability only, considering target Fs of 1.30 for stability and Fs =1.5 against pullout.  The search in Design is limited to circles emerging at the toe (see the distribution of Fs; it shows points used in ReSSA at the crest only).

42. Results of Spencer Analysis (Direct Sliding) in Design Mode: This dialog shows the resulted layout satisfying the prescribed factor of safety against direct sliding, Fs = 1.30.  The length of each layer satisfies this design requirement. 

43. Synergistic Results in Design Mode:  This dialog shows the superimposed layouts of reinforcement.  The designer can clearly see the predominant stability requirement.  From within this dialog, the user can rerun the problem to verify the safety factors for the synergistic layout.

44. Printing of Report:  ReSSA can print a comprehensive report of results, including the details of input data.  Upon clicking on Print (or Print Preview) on the toolbar, this dialog appears.   The user through the selection of the desired subjects determines the content of the report.    Note that the printed report is in addition to the option to print certain graphical results screens. 

45. Drawing Exchange Format (DXF): Upon clicking on a button on the toolbar, the user can create a DXF file.  The content of the file may include the soil profile, the reinforcement, tension crack, water surface(s) and all critical slip surfaces.  Such a file can be imported to AutoCAD® for further processing and integration into construction blueprints. 

46. Publication No. FHWA-NHI-00-043:  By clicking on the Help menu, the new edition of Demonstration Project 82 can be invoked.  It is provided as a pdf file.  A copy of the Adobe® Acrobat® Reader is provided with the installation CD of ReSSA in case the user does not have this software.  The manual can be accessed via links in its table of contents, just scrolled through, or searched using keywords.  Its content can be printed.