BS-Theory: 2nd order theory -Teil 1

The differential equation for a normal flexural member is:

EI w''''(x) = q(x)

The normal force N is taken into consideration for a buckling member:

EI w''''(x) + N w''(x) = q(x)

For the sake of completeness, the differential equation for an additionally bedded system is shown here since the program also allows parallel processing of systems with 2^nd order theory and elastic bedding. The equation is:

EI w''''(x) + N w''(x) + k_s w(x) = q(x)

Analysis is performed on the deformed system. In

• DIN EN 1993-5
  Design of Steel Structures,
  Part 5: Piling

analysis using 2^nd order theory is recommended for analysis of sheet pile walls under buckling loads. DIN EN 1993-5 refers to

• DIN EN 1993-1-1
  Design of Steel Structures,
  Part 1-1: General Rules and Rules for Buildings

for these analyses. Analysis using 2^nd order theory produces more accurate results than the usual and simplified equivalent member method.