D3.C.6 Design Parameters

Available design parameters to be used in conjunction with BS5400 are listed in table 2C.1. Depending on the value assigned to the WET parameter, you can determine the stage under consideration. For a composite design check, taking into consideration the construction stage, two separate analyses are required. In the first, member properties are non-composite and the WET parameter is set to 1.0 . In the second, member properties should be changed to composite and the WET parameter set to 2.0. Member properties for composite or non-composite sections should be specified from user provided tables (refer to section 5.19 of the manual for specification of user tables). Rolled sections, composite or non-composite, come under WIDE FLANGE section-type and built-up sections under ISECTION. When specifying composite properties the first parameter is assigned a negative value and four additional parameters provided giving details of the concrete section. See user table examples provided.

Note: Once a parameter is specified, its value stays at that specified number until it is specified again. This is the way STAAD.Pro works for all codes.

Table 1. BS5400 Design Parameters
Parameter Name	Default Value	Description
ESTIFF	0	Specify the criteria used for the design of compression members with moments. 0. Member passes if either Cl. 4.8.3.3.1 or Cl. 4.8.3.3.2 check. 1. Member passes if both Cl. 4.8.3.3.1 and Cl. 4.8.3.3.2 check.
KY	1.0	K value for bending about Y-axis. Usually this is minor axis.
KZ	1.0	K value for bending about Z-axis. Usually this is major axis.
LY	Member Length	Length to calculate slenderness ratio for bending about Y-axis, in current units of length.
LZ	Member Length	Length to calculate slenderness ratio for bending about Z-axis, in current units of length.
MAIN	1.0	Grade of concrete: 1. 30 N/mm2 2. 40 N/mm2 3. 50 N/mm2
NSF	1.0	Net section factor for tension members.
PY	*	Yield stress of steel. Set according to Design Strength of steel SGR
RATIO	1	Permissible ratio of actual to allowable stresses.
SBLT	0.0	Steel 0.0 = Rolled Section 1.0 = Built up Section
SGR	0.0	Steel Grade per BS4360 0. Grade 43 1. Grade 50 2. Grade 55
TRACK	1.0	Used to control the level of detail in the output 0. Suppress all member capacities 1. Print all member capacities
UNL	Member Length	Unsupported length for calculating allowable compressive bending stress, in current units of length.
WET	0.0	Used to specify the stage of construction. 0. Wet stage with no data saved for composite stage 1. Wet stage with data saved for composite stage 2. Composite and wet stage combined 3. Composite stage only