National Design, Construction and Soil Mechanics Center

NRCS Structural Design Software

· This suite of web based software will structurally analyze and design various NRCS standardized, reinforced concrete hydraulic structures. The input includes structure geometry, backfill depths, water heights, soil parameters, and material strengths. The output includes stability safety factors, required member thicknesses, concrete volume, and reinforcing amounts. Availability of this software on the web was announced with National Bulletin 210-5-7.

· This suite was originally developed in FORTRAN for mainframe execution during the 1970’s. The assumptions, analysis methods, required inputs, design algorithms, and sample outputs for each program were documented and distributed in a series of Technical Releases (TRs). The concrete design is primarily based on ACI 318-54 Working Stress Design and should be adequate compared to most current criteria.

· The original programs and documentation were written by Dr. Ed Alling, Head and his staff at the former SCS National Design Unit in Maryland.

· The STRUCHAN and SAFBASIN programs have been enhanced by the U S Army Corps of Engineers (USACE) to add additional analysis and output features. Their versions, CCHAN and CBASIN, are included in their Computer Aided Structural Engineering (CASE) collection and are adopted here with their permission.

· The DROPSPIL program was further enhanced by Dr. Alling after retirement and obtained by SCS for unlimited use.

· These current versions were developed at Kansas State University with ARS and NRCS assistance.

PROGRAM	SUBJECT	REFERENCES
SINGCELL	single cell rectangular box conduit	former TR42	NEH636.58
TWINCELL	twin cell rectangular box conduit	former TR45	NEH636.59
CCHAN	U-shaped rectangular channel	former TR50	NEH636.66
CBASIN	Saint Anthony Falls stilling basin	former TR54 former TR54-1	NEH636.78
DROPWS3E	Type C or B straight drop spillway	former TR63	NEH636.74
Note: Links to above programs and documents will be added as they become available. CCHAN and CBASIN are currently the older SCS structural design software programs which will be updated to the CASE programs when available.

These design programs by nature make numerous design assumptions for structure geometry, backfill heights, water pressure, material parameters, etc. Many are software default values which can be overwritten. The user needs to review all assumptions and assure that the software designed structure will satisfy the particular site conditions.

Questions on the technical aspects of these applications should be directed to engineers at the NRCS National Design Construction and Soil Mechanics Center in Fort Worth, TX.

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