Updated quick design tables for combined wall structures
February 17, 2021 8:27 CET 6 min read
Quick design tables for combined wall structures have been made to ease the design of retaining walls containing tubular steel piles and sheet piles. Now these tables have been updated to follow the latest versions of Eurocode design standards.
Figure 1. Combined wall structures
Previous version of the tables had also some type errors in cross-section values of the walls.
Cross-section values and resistance values in tables
The tables in the manual contain all standard pile sizes in the range of SSAB large diameter piles (D = 406 mm … D = 1220 mm). For all these piles sizes there are totally six tables for different types and sizes of sheet piles. For example Table 1 is for combined wall with secondary piles of double U type sheet piles having width of 600 mm, Table 2 is also for U type sheet piles having width of 600 mm but with triple piles.
Tables contain bending stiffness I [cm4/mm] as well as both elastic section modulus Wel [cm3/m] and plastic section modulus Wpl [cm3/m]. Bending moment resistance MRd [kNm/m] is included for three different steel grades, S355J2H, S440J2H and S550J2H. Example of the table is shown in Figure 2. These resistance values offer designer a valuable tool to compare the effect of steel strength to resistance of the structure. Often the reduction in material gained with higher steel grade offers significant reduction to total cost of material in combined wall structure.
Figure 2. Example of table values in the manual
Local buckling of cross-section class 4 piles
Design standard EN 1993-1-6 for strength and stability of shell structures is used to calculate the local buckling resistances of tubular steel cross-sections belonging to cross-section class 4. The resistance values against local buckling in the tables have now updated to follow the latest version of this standard. Due to this update the resistance values have increased slightly.
Design standard EN 1993-5 for steel piles allows designer to neglect the local buckling, if certain criteria is fulfilled. The criteria is explained in standard and it refers to filling of piles with high grade compacted soil or with concrete. For such cases the tables have also resistance values where local buckling has not been considered. These values are shown inside brackets .
More information on Combined walls www.ssab.com/infra