Steel Pile News
RR245 New pile size with mechanical splices and rock shoes
May 18, 2020 17:21 CEST 6 min read
SSAB presents new pile size RR245. New pile size is available as RR pile elements with mechanical splices and pile shoes.
New pile size fits well between RR220 and RR270 pile sizes and at the same time it widens the range of pile sizes having RR pile elements with mechanical splices and mechanically attached rock shoes.
High strength RRs245 piles made of SSAB’s S550J2H steel grade offer economical solution with higher resistances than RR270 piles made of S460MH steel grade. Besides being more economical solution, RRs245 piles made of high strength steel offer also more sustainable solution due to less steel material needed. Comparisons of these pile sizes are shown below.
Technical properties of new RR245 pile size
New RR245 pile size has two alternative wall thicknesses and two possible steel grades:
The design resistances of the new RR245 pile size in different soil conditions and in different countries are given in following tables.
Advantages of new RRs245/10 and RRs245/12.5 pile sizes
Following graphs show the design resistances of RRs245/10 and RRs245/12.5 pile sizes compared to RR270/10 (D=273.0, t=10.0) and RR270/12.5 (D=273.0, t=12.5) pile sizes. The graphs show the design resistances of piles in different soil conditions.
In graphs the undrained shear strength of soil (cu) is shown in horizontal axis and the design resistance (Rd) of pile is shown in vertical axis. With low values of cu the soil around the pile limits the design resistance of the pile and the pile buckles. This is shown with rising curves in graphs. After certain strength of soil, the geotechnical end bearing resistance of pile toe limits the design resistance. This is shown with vertical lines in graphs.
The graphs have been prepared to Finland, Sweden and Norway. In all these countries the design rules of piles are based on Eurocodes and national rules. Due to national rules the calculation methods and therefore also the resistances of piles are different in each country. The presumptions of the calculations are given in the graphs.
The graphs show that in most soil conditions the new RRs245 pile sizes made of S550J2H steel grade have higher design resistances than RR270 pile sizes made of S460MH steel grade. Due to lower weight of the pile, RRs245 pile offers also more economical and environmentally friendly solutions.
Testing of new pile sizes
New RR245 pile size has been tested and it fulfills the criteria given for rigid pile splices and rock shoes. Tests consist of two phases, first impact blow tests at site conditions and then laboratory tests for the same samples.
At impact blow tests the piles are driven against the bedrock. The test consists of at least 500 impact blows with stress level of ≥ 0.75 times the yield strength of steel grade in question. With S550J2H steel grade this means stress level of at least 412.5 MPa. The stress level is monitored with PDA equipment throughout the whole test.
New RRs245/12.5 pile with mechanically attached rock shoe after impact blow test.
After impact tests the piles are lifted up and inspected visually. The piles are taken to laboratory to go through set of another type of tests. The splices are tested for bending resistance, bending stiffness, compression resistance and tension resistance.
More information on RR® and RD® piles www.ssab.com/infra