1. SORMAT
BASICS OF ANCHORING THEORY, (Part 2)

2. Contents
1 Mechanical Anchors……………
2 Chemical Anchors………………………
3 Fire Resistance of Anchors……………
4 Corrosion Rsistance of Anchors
5 Throughbolts..……………………………………………… 18
Multi-Monti Concrete Screw
Drop-in Achors……………………………………………… 24
Undercut Anchors…………………………………………. 27
Chemical Anchors……………………………………….. 30

3. 1 Mechanical Anchors 1.1 General SORMAT ANCHORING THEORY
It is typical for mechanical anchors that they transfer loads into base material by direct contact and they are classified according to their physical principles to transfer loads from anchor into base material.
Friction
Undercut
Undercut + friction
Drop-in anchor
Through bolt
Sleeve anchor
Undercut anchor
Screw anchor
No further expansion
Further expansion

4. 1 Mechanical Anchors 1.2 Expansion Achors 1.3 Undercut Anchors
SORMAT ANCHORING THEORY
1 Mechanical Anchors
1.2 Expansion Achors
Expansion anchors produce wedge forces and frictional forces in the base material. With torque controlled expansion achors, a specified installation torque is applied. Thereby cone or cones is/are drawn into the expanding sleeve segments. Due to the pre-tension in the anchor rod or to an external tensile load, torque controlled anchors expand further, but only if the friction between cone and sleeves is smaller than between sleeves and concrete. Torgue controlled anchors are mainly used for group and single fastenings in the medium and high load ranges.
Displacement controlled anchors are expanded by driving the cone into the sleeve (drop-in anchor) or the sleeve over the cone (outcone anchor). These anchors are mainly used for multiply fastenings in the medium and low load range.
1.3 Undercut Anchors
Undercut anchors are anchors with parts that spread and mechanically interlock with the concrete base material. Much lower expansion forces are produced during installation and loading than with expansion anchors. If the shape of the undercut is well adopted and its depth is sufficient, an undercut anchor acts virtually identically to cast-in fixings, i.e. both achiev the same ultimate loads, because the undercut achor optimally uses the high resistance to compression forces of the concrete. Undercut anchors are used to fix medium and high loads with an exellent reliability.

5. 1 Mechanical Anchors 1.4 Screw Anchors (Concrete Screws)
SORMAT ANCHORING THEORY
1 Mechanical Anchors
1.4 Screw Anchors (Concrete Screws)
The thread of screw anchor cuts into the concrete and transmits tensile loads by this threaded undercut into the wall of the drill hole. Friction avoids the loosening and turning out of the screw. The working principle is mixture of undercut anchors and chemical anchors. Screw anchors are used for medium loads.

6. 1 Mechanical Anchors 1.5 Working Principles of Mechanical Anchors
SORMAT ANCHORING THEORY
1 Mechanical Anchors
1.5 Working Principles of Mechanical Anchors
Anchors used in walls and on floors are generally subjected to shear or compined shear and tensile loads. One of the few applications, where anchors are submitted to pure tensile load is the suspension of ceilings. Altough most of the anchors are subjected to shear loads, the shear resistance is mainly influenced by the substrate. Edge distances and quality of the substrate are more strongly influencing the shear behavior than the tensile resistance of anchor. Further for the shear load introduction into the substrate only the rod and if available the sleeve with the rod are relevant. The real anchor mechanism, normally placed deep in the hole, only prevent the anchor to slip out at further displacements.

7. SORMAT ANCHORING THEORY
1 Mechanical Anchors
1.6 Behavior of Mechanical Anchors in Cracked Concrete
In the areas where a concrete member is under tensile stress, the concrete is usually loaded over its tensile capacity and the cracks most often run through the anchor holes. Drop-in achors loose about 50 % of their bearing capacity in a crack of 0,3 mm width, and the capacity of torque controlled anchors is reduced to 70 % of the value attained in uncracked concrete. Under cut anchors with sufficient undercut depth may be used up to their full steel tensile capacity also in cracked concrete. The great advantage of undercut anchors, intelligently designed for steel failure, is that concrete quality and tensile or compression zone need not be considered in their calculations. However, the detailing rules concerning edge distances and spacing must be respected.

8. 2 Chemical Anchors 2.1 General
SORMAT ANCHORING THEORY
2 Chemical Anchors
2.1 General
Chemical anchors are characterized by the use of bonding agent fixing the anchor to the concrete and are detailed by the application method and the chemical ingredients of the adhesive. The usual application methods are the capsule systems and the injection systems. The ingredients are divided into organic and inorganic compounds.
2.2 Working Principles of Chemical Anchors
Similar to the mechanical anchors the shear behavior of the chemical anchors are mainly influenced by the rod. The mortar provides a very good behavior for dynamic loads by filling the gap between anchor and substrate completely and prevent the system from displacement. Therefore the further explanations are reduced to introduction of tensile loads.

9. 2 Chemical Anchors 2.3 Design of Chemical Anchors for Tensile Loads
SORMAT ANCHORING THEORY
2 Chemical Anchors
2.3 Design of Chemical Anchors for Tensile Loads
With adhesive anchors different failure modes can be observed. If the embedment depth is small, usually a concrete cone is pulled out. If the embedment depth is deeper, a combined failure including a shallow concrete cone with bond failure below the cone is typically observed. The bond failure can be at the adhesive / concrete interface or the anchor / adhesive interface or a mixture of both. If the embedment depth is deep enough, steel failure occures in the anchor. The minimum depth for steel failure represents the basic development length of the anchor, which depends on the steel quality, the properties of the bonding agent and the concrete quality.
Concrete
Resin/concrete
Anchor/ resin
Anchor/ resin and
Resin/anchori
Steel

10. SORMAT ANCHORING THEORY
2 Chemical Anchors
2.4 Behavior of Chemical Anchors in Cracked Concrete
For the load introduction into substrate it is necessary to transfer load from the rod into mortar and from mortar into the substrate. The load transfer into the mortar for anchors suitable in cracks is normally managed by a rod with cones. The cones can be described like an undercut in the mortar. The size of the cone has to be sufficient to transfer load in cracks up to 0,3 mm. The roughness of the substrate is not sufficient to transfer load, if crack is crossing the joint. Therefore it’s aimed to create the crack through the mortar. To prevent a detaching of the mortar from the substrate sometimes a coating of the rod is used.

11. 3 Fire Resistance of Anchors
SORMAT ANCHORING THEORY
3 Fire Resistance of Anchors
3.1 Temperature Curves
Figure shows the actual valid temperature-time-assumptions on which the fire tests for anchors are based. The significant point of the tunnel temperature curves is the very fast increase of the temperature over 1000 ºC.

12. 3 Fire Resistance of Anchors
SORMAT ANCHORING THEORY
3 Fire Resistance of Anchors
3.2 Fire Impact on Anchors
It is quite usual, that electromechanical installations, plumming and false ceilings are fixed by anchors. These anchors have to quarantee for the design fire load the safe access of the emergency crews. They have to be designed to withstand the impact of the relevant temperature/time curve, i.e. the emergency crews are not exposed to falling debris.
Fire in Mont Blanc tunnel

13. 3 Fire Resistance of Anchors
SORMAT ANCHORING THEORY
3 Fire Resistance of Anchors
3.2 Fire Impact on Anchors
Anchors have been therefore submitted to fire tests under different fire curves at the German Institute IBMB of Thecnical Univercity of Brunswick, Germany. Tensile loads of anchors made of normal steel and of high-corrosion resistant steel EN in cracks of 0,2 mm and direct fire impact without protection of the anchor, have been tested. The results of these tests are the followings:
At high temperatures, the base material breaks down (spalling of concrete). The damaged area increases with the duration of the fire according to the temperature exposure. Setting an anchor therefore deeper, helps to keep the anchor intact in cocrete substrate.
Allthough metal does not burn, its loading capacity decreases with increasing temperature (especially from about 500 ºC upwards). This is shown during the fire test, by slipping nuts or breaking of anchor rods.
As the temperature increases, the loading capacity of the base material and the anchor decreases. The conclusion is, that the load must be reduced below the level of the normal recommended load necessary for ordinary steels to achiev the desired fire rating.

14. 3 Fire Resistance of Anchors
SORMAT ANCHORING THEORY
3 Fire Resistance of Anchors
3.3 Summary
Fire tests have proved, that behavior of stainless steel is better than as of normal carbon steel. Generally it can be stipulated, that the tensile fire loads of stainless steels are twice as for carbon steels.
Fire resistant anchorings have to be carefully designed especially due to the exceptional high fire loads in tunnels. The relevant anchors are available on the market and the design method is known, but it will take quite an effort to convince tunnel owners to understand importance of ”Fire Fastening Design”, because the cost will be somewhat higher, but still reasonable in relation to the total tunnel costs.

15. 4 Corrosion Resistance of Anchors
SORMAT ANCHORING THEORY
4 Corrosion Resistance of Anchors
Ever since metallic materials have been used in the construction industry, building and civil engineers have faced problems of corrosion and protection against corrosion. As early as the Middle Ages, fasteners made of iron and iron alloys were used, e.g. as staple-like clamps and fasteners, for securing building components. They were positioned in such a way that they remained accessible and could be maintained. In the more recent past, however, engineers believed that corrosion problems could be overcome by using stainless steel and covering steel members and components more with concrete. During past decades, there has been a great increase in the exposure of certain areas to pollutants, e.g. technical facilities for traffic. This trend has resulted in previously used materials reaching the limits to their capabilities. Even today, materials used for building and structures situated in corrosive enviroments have an unsatisfactory service life in many cases.
In the field of composite construction, in particular, problems from corrosion are not restricted only to zones exposed to the atmosphere. As a rule, a corrosive medium gains access to a metal connector or other fastener, etc. through, for example cracks which appear in concrete or gaps which exist in structure. Gaps of this kind can be result of the structural design, such as those between original concrete and a concrete overlay on repaired bridges. In the course of time pollutants such as chlorides and corrosive acids, can accumulate, producing considerably more corrosive conditions in this way.

16. 4 Corrosion Resistance of Anchors
SORMAT ANCHORING THEORY
4 Corrosion Resistance of Anchors
Corrosion seriously impairs the functioning and service life of anchors as well as of other fasteners, while, as a consequence, possibly creating a considerable safety risk. There have been done several field tests and laboratory tests by different manufactures and univercities in different enviroments as tunnels, swimming halls, power plant’s chimneys and etc. These tests have proved that it is necessary to pay attention to right materials. For example it was found that the high-alloyed austenitic steel according to EN , which has a molybdenum content greater than 6 % and nickel content high over 20 %, is ideal for use in construction in highly corrosive surroundings (chlorides and sulphur dioxide).

17. 4 Corrosion Resistance of Anchors
SORMAT ANCHORING THEORY
4 Corrosion Resistance of Anchors
Pitting corrosion of the material (A4) after exposure to a road tunnel atmosphere for 2 years.
Principal of pitting corrosion
Development of pitting corrosion (only indicative).

18. SORMAT ANCHORING THEORY
5 Throughbolts

19. 5 Through bolts 5.1 Facts, which affect into function of the anchor
SORMAT ANCHORING THEORY
5 Through bolts
5.1 Facts, which affect into function of the anchor
Installation hole
- Too small hole (worn out drill bit, wrong drill bit).
 Difficult to install. Anchor can damaged.
- Too big hole (worne out drill bit, wrong drill bit).
 Easy to install, but pull-out values will decrease considerably.
- The depth of the hole is not deep enough.
 Anchor can not be installed deep enough, then the capacity will decrease. Also there is not enough space for the remaining dust.
- Hole is too deep.
 It is important to pay attention to member thickness. Otherwise too deep hole has no influence.

20. 5 Through bolts 5.1 Facts, which affect into function of the anchor
SORMAT ANCHORING THEORY
5 Through bolts
5.1 Facts, which affect into function of the anchor
Cleaning of the hole:
Clean
It is easier to install the anchor.
Anchor will go deep enough.
Friction between the hole and the anchor is higher.
Pull-out values are according to the the given values.
Dirty
Anchor is more difficult to install.
Anchor won’t go deep enough.
Friction between the hole and anchor is lower.
Pull-out values will decrease.
Tightening torgue:
Right
Anchor won’t slide too early.
Pre-tension according to the design values.
Behaviour of the anchor according to the design.
Wrong (too low or too high)
Anchor will slide too early. (low)
Pre-tension too high. (high)
 Danger of cracking.
Anchor might break by tightening. (high)
Behaviour of the anchor is not according to the design. (low)

21. 5 Through bolts F 5.2 Concrete Cone SORMAT ANCHORING THEORY n. 135 º
Expansion clip will create friction forces, which are higer than binding forces of the concrete.

22. 6 Multi-Monti (Concrete Screw)
SORMAT ANCHORING THEORY
6 Multi-Monti (Concrete Screw)

23. 6 Multi-Monti (Concrete Screw)
SORMAT ANCHORING THEORY
6 Multi-Monti (Concrete Screw)
6.1 Facts, which affect into function of the anchor
Installation hole
- Too small hole (worn out drill bit, wrong drill bit).
 Difficult to install. Anchor can damaged.
- Too big hole (worne out drill bit, wrong drill bit).
 Easy to install, but pull-out values will decrease considerably.
- The depth of the hole is not deep enough.
 Anchor can not be installed deep enough, then the capacity will decrease. Anchor might break after over tightening
- Hole is too deep.
 It is important to pay attention to member thickness. Otherwise too deep hole has no influence

24. 6 Multi-Monti (Concrete Screw)
SORMAT ANCHORING THEORY
6 Multi-Monti (Concrete Screw)
6.1 Facts, which affect into function of the anchor
Cleaning of the hole:
Clean
Anchor is easier to install.
Anchor will go deep enough.
Dirty
Anchor required high by the installation.
Anchor won’t go deep enough.
 Danger of breaking of the anchor.
Tightening torgue:
Multi-Monti doesn’t have required tightening torque. Anyway it is important not to over-tight Multi-Monti because it might break by over-tightening.
Recommended maximum tightening torques are:
6 mm 12 Nm
7,5 mm 20 Nm
10 mm 50 Nm
12 mm 80 Nm
16 mm 150 Nm

25. SORMAT ANCHORING THEORY
7 Drop-in Anchors

26. 7 Drop-in Anchors 7.1 Facts, which affect into function of the anchor
SORMAT ANCHORING THEORY
7 Drop-in Anchors
7.1 Facts, which affect into function of the anchor
Installation hole
- Too small hole (worn out drill bit, wrong drill bit).
 Difficult to install. Anchor can damaged.
- Too big hole (worne out drill bit, wrong drill bit).
 Easy to install, but pull-out values will decrease considerably.
- The depth of the hole is not deep enough.
 Anchor can not be installed deep enough, then the capacity will decrease. The fixture doesn’t tighten against the base material. - Hole is too deep.
 It is important to pay attention to member thickness.
 Longer screws are needed.
 Installation will be more difficult, because it is impossible to see when istallation tool touch the anchor.

27. 7 Drop-in Anchors 7.1 Facts, which affect into function of the anchor
SORMAT ANCHORING THEORY
7 Drop-in Anchors
7.1 Facts, which affect into function of the anchor
Cleaning of the hole:
Clean
Anchor will be easier to install.
Anchor will go deep enough.
Friction between the hole and anchor is higher.
Pull-out values are according to the given values.
Dirty
Anchor will be more difficult to install.
Anchor won’t go deep enough.
Friction between the hole and anchor is lower.
Pull-out values will decrease.
Tightening:
Right
Anchor won’t slide too early.
Pre-tension according to the design.
Behaviour of the anchor is according to the design.
Wrong (low or high)
Anchor will slide too early. (low)
Pre-tension too high. (high)
 Danger of cracking.
Anchor might break by the tightening. (high)
Behaviour of the anchor is not according to the design. (low)

28. SORMAT ANCHORING THEORY
8 Undercut Anchors

29. 8 Undercut Anchors 8.1 Facts, which affect into function of the anchor
SORMAT ANCHORING THEORY
8 Undercut Anchors
8.1 Facts, which affect into function of the anchor
Installation hole
- Too small hole (worn out drill bit, wrong drill bit).
 Difficult to install. It might be impossible to install the anchor.
- Too big hole (worne out drill bit, wrong drill bit).
 Easy to install
 Might effect to pull out values of the self cutting ucercut anchors.
- The depth of the hole is not deep enough.
 Anchor can not be installed deep enoug and installation will fail.
- Hole is too deep.
 It is important to pay attention to member thickness. Otherwise too deep hole has no influence.

30. 8 Undercut Anchors 8.1 Facts, which affect into function of the anchor
SORMAT ANCHORING THEORY
8 Undercut Anchors
8.1 Facts, which affect into function of the anchor
Cleaning of the hole:
Clean
Anchor will be easy to install.
Anchor will go deep enough.
Dirty
Anchor will be more difficult to install.
Anchor won’t go deep enough.
Tightening torque:
Right (superplus)
Pre-tension according to the design.
Behaviour of the anchor according to the design.
Wrong (too low or too high)
Anchor will slide a bit by the loading. (low)
Pre-tension too high. (high)
 Danger of cracking.
Anchor might break by tightening. (high)
Right (ultraplus)
Will attach only the fixture.
Wrong (too low or too high)
Practically there is no influence if torque is too low or too high.

31. SORMAT ANCHORING THEORY
9 Chemical Anchors

32. 9 Chemical Anchors 9.1 Chemical Capsules
SORMAT ANCHORING THEORY
9 Chemical Anchors
9.1 Chemical Capsules
9.1.1 Facts, which affect into function of the anchor
Installation hole
- Too small hole (worn out drill bit, wrong drill bit).
 Difficult to install. It might be impossible to install the anchor.
 The thickness of the mortar layer between the hole and stud will be too small – might affect to the pull-out values.
- Too big hole (worne out drill bit, wrong drill bit).
 Easy to install
 Might affect to pull-out values, because the hole won’t be filled up completely.
- The depth of the hole is not deep enough.
 Anchor can not be installed deep enoug and installation will fail.
- Hole is too deep.
 It is important to pay attention to member thickness.

33. 9 Chemical Anchors 9.1 Chemical Capsules
SORMAT ANCHORING THEORY
9 Chemical Anchors
9.1 Chemical Capsules
9.1.1 Facts, which affect into function of the anchor
Cleaning of the hole:
Clean
Anchor will go deep enough.
The dust won’t decrease the bond between the hole and the mortar.
Pull-out values according to the design.
Dirty
Anchor won’t go deep enough.
The bond between the hole and the mortar is lower.
Pull-out values will decrease (max. 20 %).
Tightening torque:
Right
Pre-tension is according to the design.
Behaviour according to the design.
Wrong (too low or too high)
The fixture might get loose. (low)
Pre-tension is too high. (high)
 Pull-out values will decrease.
Anchor might break by tightening. (high)

34. 9 Chemical Anchors 9.2 Chemical injection Resins
SORMAT ANCHORING THEORY
9 Chemical Anchors
9.2 Chemical injection Resins
9.2.1 Facts, which affect into function of the anchor
Installation hole
- Too small hole (worn out drill bit, wrong drill bit).
 The thickness of the mortar layer between the hole and stud will be too small – might affect to the pull-out values.
- Too big hole (worne out drill bit, wrong drill bit).
 Normally doesn’t affect to the anchorage (Note! Small stud – big hole)
- The depth of the hole is not deep enough.
 Anchor can not be installed deep enough and pull-out values will decrease.
- Hole is too deep.
 It is important to pay attention to member thickness.
 Doesn’t affect to anchorage

35. 9 Chemical Anchors 9.2 Chemical injection Resins
SORMAT ANCHORING THEORY
9 Chemical Anchors
9.2 Chemical injection Resins
9.2.1 Facts, which affect into function of the anchor
Cleaning of the hole:
Clean
Anchor will go deep enough.
The dust won’t decrease the bond between the hole and the mortar.
Pull-out values according to the design.
Dirty
Anchor won’t go deep enough.
The bond between the hole and the mortar is lower – Pull-out values will decrease up to 60 %.
Tightening toeque:
Right
Pre-tension according to the design.
Behaviour of the anchor according to the design.
Wrong (too low or too high)
Fixture might get loose.(low)
Pre-tension is too high. (high)
 Pull-out values will decrease.
Anchor might break by tightening. (high)

36. Thank you for your interest! SORMAT OY
SORMAT ANCHORING THEORY
Thank you for your interest!
SORMAT OY