What Is A Tie Rod

If static and structural conditions require the anchoring of a pile wall, this is achieved by mutual support, for example with channel excavations. In most cases, however, piles need to be additionally tied back.
The anchorage constructions are chosen and constructed according to static and structural requirements. Reaction force A, resulting from static calculations of the pile wall, as well as the low skidding joint analysis are decisive for dimensioning.
Waling diverts forces from the sheet pile to the anchorage, and simultaneously aligns and stiffens the construction. The anchorage diverts the reaction force of the pile through the waling to the anchorage body.
The anchorage body, again, divert such forces from the main pile to the soil. An anchor wall forms the anchorage body for a round steel anchorage.
If the construction is embedded through anchor piles, e.g. steel bearing piles, injected bearing piles, forces from the pile are diverted to the soil through pile skin friction.

Dimensioning of the anchorage parts (E 20 of the EAU 1990)
Anchor piles, waling, beams and support plate: Bearing capacity analysis is to be carried out according to DIN 18800 or DIN V ENV 1993-5, if stress is mainly consistent. In case of waling and beams, the requirements for an increase of the partial safety coefficients according to E 30 must be considered.
Alternating stress requires the fatigue strength analysis according to DIN 19704-1. We would also like to stress the importance of DIN 18800, Part 1.
In general, dead steel according to DIN EN 10025 must be used.
Fitting bolts, with min. Tensile strength, are to be used for threaded waling and beam splices. The fatigue strength analysis is to be carried out according to DIN 18800, Part 1.
Tie-rods and waling bolts: Anchorages are mainly subject to static load. Strong fluctuating stress is rare in anchorages, but nevertheless occurs often in waling bolts. Tie-rods and waling bolts must be made of steel types according to DIN EN 10025. The steel type S 355 J2G3 is the most commonly used steel. In general, dimensioning for constructions with mainly static load are based on the anchoring forces which result from loads accor- ding loading case 2. Bearing capa- city analysis is to be carried out accor- ding to DIN 18800, part 1. The reducing coef- ficients for the loading cases 1 to 3, must be observed.

DIN 4125 applies for the construction and dimensioning of anchorage by means of grout anchors. Only completely dead steel types are to be used in construction with fluctuating loads. The bearing capacity analysis is to be carried out according to DIN 18800, part 1. If the static base load is less or equal to the alternating load, controlled and permanent stressing of anchorage and/or waling bolts above the stress amplitude is recommended.