PSBEAM CAPABILITIES
Psbeam may be used to design or review prestressed concrete beams with either pretensioning or post-tensioning reinforcement. Options are available to calculate stresses, deflections, ultimate moment capability and shear stirrup design.
Program input may be supplied interactively by filling in the GUI tab control form or via an externally created file. Input files may be saved for later editing and reuse. This program currently supports English units only. Input paramters should be entered as specified under Units in the Program options section.
Prestressed concrete beam design may be performed using either AASHTO (1996), AREMA (2002) or ACI-318 (1999) design criteria. The program has built in default values for material properties, allowable stresses and prestress losses which change depending on the design criteria selected. The most conservative values are used when the codes allow optional increased allowables based on certain conditions. For example, ACI-318 allows higher compressive stresses in the concrete if the load is short term, however the default values show the minimum value allowed. Calculations for ultimate moment and shear are performed consistent with the selected design criteria.
The calculations may be made using either the gross or transformed section properties of the beam section. Only gross section properties are used when determining the initial prestress force.
Composite beams may be specified by including the composite slab option. The program can calculate the effective width of the slab or the user may specify it directly.
The program has built-in section properties for several standard precast beam sections, including I-girders, box girders, voided slabs, solid slabs and trapezoidal box girders. The user may also specify a general section for prestressed concrete beam design, however the program will not calculate the ultimate moment and shear capability due to lack of web and flange descriptions. Variations on the built-in sections may be made by specifying the dimensions and using the program’s built-in section property calculation capability.
A variety of loads may be specified at any number of locations along the beam, including beam dead load, non-composite dead load, composite dead load, live load plus impact, secondary prestress load and miscellaneous load. Only the locations specified will be checked, therefore it is important for the user to specify all critical sections of a beam.
The program allows specification of six prestress paths, including straight, harped, simple-simple parabolic, simple-fixed parabolic, fixed-simple parabolic and fixed-fixed parabolic. The program internally calculates the cable eccentricities from the specified prestress path dimensions.