Jordahl - Deutsche Kahneisen GmbH : FAQ for ETA

Is it possible to cut the anchor channels into the pieces?

Which is the standard filling material for which profile size?

Does the bracket with slotted holes for adjustment, and locked by a serrated washer, need to be considered as a slotted bracket and how do I classify the degree of restraint?

Is it possible to design the anchor channel for dynamic/fatigue loading in Expert^® Software?

How do I know which anchor channel is suitable for seismic and/or cracked concrete?

Is it necessary to use special anchor channels in cracked concrete

What is T_inst? Why is it necessary to maintain T_inst specified values?

What does "Cracked Concrete" mean?

Why is there a filler material inside the anchor channel and what is the difference between white and blue filler material?

What is the difference between round anchors (R) and I-anchors? Do they have same load carrying capacities?

How do I know that the bolt is correctly placed inside the anchor channel?

Can I improve the load carrying capacity of JORDAHL® anchor channels by using high quality concrete? 

What are the other ways of increasing the load carrying capacity of JORDAHOL^® anchor channels?

Can I position the loads along the longitudinal direction of the anchor channels without using the toothed anchor channels?

Can I increase the load carrying capacity of anchor channels with the help of additional reinforcement?

Can I fix the load position in Expert? 

Why does the load position change during the design of anchor channels in JORDAHL^® Expert software?

What does the JORDAHL^®ESA method mean?

Is it possible, that anchors other than the ones shown in JORDAHL® Expert software are utilized to a higher degree?

What are the benefits of hot-rolled profiles against cold-formed profil

Are there different types of stainless steel for anchor channels?

Is the ETA 09/0338 also valid for stainless steel?

Is the ETA 09/0338 also valid for toothed anchor channels?

Is there any information about dynamic loads for anchor channels in the ETA 09/0338?

What are the advantages of the new design according to ETA?

What is the meaning of the acronym ETA?

Can the calculation of the same situation according to ETA and to the old national approval lead to different results?

What are the changes in the profiles, anchors and spacing?

Is there a design software for anchor channels?

What is CEN / TS 1992-4:2009?

Are there any changes in the installation of the anchor channels?

How does Jordahl^® Expert determine the decisive anchor?

Is it possible, that other anchors than the decisive are higher utilised?

Cutting is possible bearing in mind that the allowable overlap at the end of the channel which is denoted by x in ETA must be maintained. After cutting, the raw edges must be galvanized with zinc spray to protect the anchor channels from corrosion.

top

Small cold formed channels (K28/15,K38/17) and mid size hot rolled channels (W40/22,W50/30) are usually filled with blue filler-PE. The bigger channels like W53/34 and W72/48) have the white filler –PS as standard because it is difficult to pull them out of bigger channels.´

top

When the bracket does not directly support the shaft of the T-bolt, the T- bolt is open to additional bending stresses. Therefore with JORDAHL^® Expert design software, you can consider having slotted holes in the bracket and additional bending of the bolt. The degree of restraint depends on the stiffness of the washer used. For typical bracket connections the recommended values are between 1.6 and 1.8. If the slots in the brackets will be filled with grout or cement floor pavement later, the bending can be avoided and no slots have to be considered in the calculation.

top

Fatigue verification should be carried out when anchor channels are subjected to regular load cycles (e.g. fastening of cranes, reciprocating machines and guide rails of elevators). Verification for the dynamic/fatigue loading can be done in JORDAHL^® Expert Software by activating the option “Dynamic fatigue loads” and by inputting the characteristic fatigue load range values (DN). In general, the calculations for the fatigue strengths are carried out on 2 million load cycles (2 x 106).

top

This depends on the category of the building, seismicity of the area and crack width limitation. For expected crack widths up to 0.5 mm, which fall in the ordinary building category and low to medium seismicity, JORDAHL® anchor channels JTA-W are tested and approved and are the recommended solution.

On the other hand, if requirements regarding the functionality and reliability of anchor channels in cracked concrete applications are very demanding and crack width limitations are higher, up to 1.5 mm e.g. safety relevant structures (power plants) and those with high seismicity, JORDAHL® provides special anchor channels JXA-PC.

top

No, there are no special anchor channels which are specifically used when considering the cracked concrete option in JORDAHL® Expert software. All the JORDAHL® anchor channels whether hot rolled (JTA-W) or cold rolled (JTA-K) are tested and approved for the normal loadings to be used in cracked and un-cracked concrete.  However, if concrete failure becomes decisive, activating the cracked concrete option might influence the load bearing capacity.

top

The design of reinforced concrete traditionally assumes that concrete is cracked wherever tensile stresses might occur. Cracks may be caused by external loads, as well as concrete creep and shrinkage, temperature variations, and settlement. As such, many reinforced concrete members are designed under the assumption that the concrete is cracked under service load. Additionally, concrete structures in regions of moderate to high seismic risk are designed assuming cracked concrete conditions. In exceptional cases, e.g. post tensioned slabs, columns and walls, the condition of the concrete can be assumed to be un-cracked.

top

T_inst refers to “Installation Torque” which is applied to the bolts during the nut tightening process. Maximum allowable values for the Tinst corresponding to the each profile type, bolt diameter and grade of T-bolt are given in the European Technical Approval (ETA-09/0338) annex 9.

If T-bolts are highly over-torqued, the bolt material can be overstressed and can damage the channel lips also causing a reduction of the load carrying capacity. On the other hand, if T_inst applied is less than the specified value it can cause movement in the fixture. Therefore, JORDAHL^® recommends using the given installation torque values as a guideline for installation.

top

The filler prevents the concrete entering the channel when it is poured into the formwork with anchor channels pre-installed. There are two types of filler materials that are used in the anchor channels: 1) white filler (polystyrol-PS) and 2) blue filler (polyethylene-PE). The blue filler was developed for environmental reasons to clean up the site. The white filler-PS is recommended when anchor channels are to be poured into self-compacting concrete.

top

Round anchors are prefabricated and are connected to the back of the channel by a mechanical process and the connection is similar to a riveted connection. Due to the automatic fabrication of round anchors, a consistent high quality can be achieved to allow a reliable connection. Compared to the I-anchors, R-anchors can be installed very easily due to a smaller anchor head.

I-anchors are welded to the back of the channel. They are wider than the round anchors.

Principally both anchors produce a similar breakout cone in concrete and attain the same load bearing capacities. 

top

On the back of the bolt, on the threaded part, there are notches called safety notches which are used to control the correct placing of the bolts into the channel. Toothed and double notch toothed bolts have two parallel notches. During the placing of bolts into the channel these safety notches must be perpendicular to the longitudinal axis of the anchor channel otherwise full load carrying capacity can not be achieved.

top

If the load carrying capacity is limited by steel resistance, there could be either a connection failure between the channel/anchor or the bolt/channel. In the first case, it is possible to reduce the distance between anchors by increasing the number of anchors. In the second case, by increasing the number of bolts, the load carrying capacity can also be increased.

top

Yes, the design of anchor channels is carried out according to the provisions of the ETA and when selecting high concrete grade, you can influence the load carrying capacity. However, it depends on the type of failure as well. If load carrying capacity is restricted due to a failure in the concrete then you can increase the concrete resistance by improving the quality of the concrete.  However, if it is a steel failure, increased resistance will not be possible.

top

Yes, basically you can increase the load carrying capacity of concrete by edge reinforcement. However, it depends on the type of failure, whether it is concrete failure or steel failure. If load carrying capacity is restricted due to a failure in the concrete then you can increase the concrete resistance with the help of additional reinforcement. However, if it is a steel failure, increased resistance will not be possible.

top

Yes, with JORDAHL^® hot rolled anchor channels it is possible to take small to medium loads along the length of the anchor channels. Then instead of using the Hook-Head or Hammer- Head bolts, special double notched toothed bolt types JKB and JKC should be used. The installation torques of these bolts are higher creating a groove inside the channel lips thereby enhancing its load carrying capacity along the longitudinal direction of the anchor channel.

top

Yes, Expert provides the option of fixing the load position. If you select the option user defined loads in the load drop down menu, you can specify the displacement field or the exact point of load application. Expert calculates on the safer side because if the fixed load position at the time of installation of the anchor channel is required to change, then there should not be any problem redesigning the anchor channel.

top

The calculation method for the anchor channels differentiates between verifying at the point where the load is acting (bolt) and the anchorage. JORDAHL® Expert automatically determines the worst load case scenario for the critical anchor. The anchor channel is then designed for this load position and is displayed on the screen and the printout.

top

Changes in the JORDAHL design methods ESA

In the European Technical Approval ETA 09/0338 the available materials are listed in Annexes 2 and 3.  ETA is also available for stainless steel in various grades for both channels and bolts. The resistances of the channels made of stainless steel correspond to those of hot-dip galvanized channels. Annexes 13 and 15 show the resistances of stainless steel bolts.

top

ETA 09/0338 is currently valid only for the JORDAHL^® anchor channels JTA for loads in tension and shear. Forces on the anchor channels in the longitudinal direction are currently being investigated. After completion of the investigation, the ETA 09/0338 will be extended for the toothed anchor channels.

top

Dynamic loads are currently not yet regulated in the CEN / TS 1992-4 and the ETA 09/0338. An enlargement of the European regulations is in progress. Currently, the dynamic load capacity of the anchor channels are taken from the national approval Z-21.4-151.

top

The design for the new ETA, in conjunction with the CEN / TS 1992-4 offers the user the exact knowledge of the safety of fastenings (e.g. in cracked or uncracked concrete) and a various other advantages. Thus, anchor channels can be calculated with different concrete strengths in the future, used with smaller edge distances, can be designed for any load positions and reinforced with stirrups. The existing conditions can thus be considered more accurate and provide a technically and economically optimized design of anchor channels.

top

ETA means European Technical Approval. The European technical approval is a proof for the fitness for use of a construction product within the meaning of the Construction Products Directive; transposed in Germany by the Bauproduktengesetz (‘Construction Products Law’).The European technical approval enables the manufacturer to place the CE marking on the construction product and thus the access to the European market.

top

A design based on the new proofs and conditions for the ETA and the CEN / TS 1992-4 can in some cases lead to different results than the previous channel selection tables for the national approval. The design methods with the new method take into account various boundary conditions and represent the current state of the art.

top

A design based on the new proofs and conditions for the ETA and the CEN / TS 1992-4 can in some cases lead to different results than the previous channel selection tables for the national approval. The design methods with the new method take into account various boundary conditions and represent the current state of the art.

top

With the introduction of the new design minor improvements were made to the products. The larger profiles get higher design resistances, the smaller anchor channels get smaller spacings. This changes will take place in early 2011. The optimized, ETA-compliant items will then have the CE mark.

top

Since the beginning of 2011 the Deutsche Kahneisen Gesellschaft offers a user-friendly software for free download. This facilitates users to switch from the previous rigid design according to tables on a flexible design according to ETA.

top

The new CEN/TS 1992-4 series is a pre-standard consisting of 5 parts which provides design methods for headed studs, anchor channels as well as post-installed mechanical and chemical fasteners for structural purposes to transmit actions into concrete and reinforced concrete structures. The CEN/TS applies to fasteners with established suitability for the specified application in concrete covered by provisions such as European Technical Approvals (ETAs). The design methods represent the actual state of the art. CEN/TS 1992-4 is valid for all applications that are within the scope of the EC 2 and will now be part of the EC 2.

top

As anchor channels are installed in principle straightforward, the installation has remained largely unchanged. Improvements were incorporated in the applied torque moments, which can now be optimised for various applications. Those can be found in the application documents or in the ETA.

top

The utilisation is calculated for every anchor and verification along the complete sliding area. The permitted sliding area is shown in the graphic display as thin line perpendicular to the load arrows. Load distances are respected. The maximum utilisation ratio for all anchors, verifications and load positions defines the decisive anchor and the critical load position.

top

Yes. E.g., if an interaction verification determines the decisive anchor, other anchors may be utilised to a higher degree by shear load while values for tension load are much smaller.

top