METHOD FOR ATTACHING ATTACHMENTS TO CONCRETE OR MASONRY

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a method for dimensioning and implementing the fastening of attachments to a mounting base formed by concrete or masonry. Furthermore, it relates to an associated computer program for dimensioning such fastenings. BACKGROUND AND RELATED ART

[0002] It is known in the art to fasten fixtures made of different materials to a concrete or masonry base. In this case, secondary (i.e., subsequently installed) anchors are always arranged perpendicular to the component surface. This is particularly evident in the international regulations currently applicable in construction technology for anchoring systems in concrete, which all require anchoring perpendicular to the concrete surface.

[0003] The basis for the design of anchorages in concrete is the characteristic resistance of the anchor for the various failure mechanisms under tensile and shear loading. The most relevant failure mechanisms with regard to tensile loading are steel failure, concrete contusion, and pull-out failure. The most important failure mechanisms under shear loading are also steel failure, concrete contusion on the opposite side of the load, and concrete edge failure. If shear forces with a lever arm occur, a bending analysis must also be performed, which in turn influences the characteristic resistance of the anchor under steel failure and can significantly reduce it, depending on the length of the lifting arm.

[0004] The following design rules must generally be observed: Quotient tensile load action and resistance: N Sd / N Rd ≤ 1, and Quotient of shear load action and resistance: V Sd / V Rd ≤ 1, Interaction condition: N Sd / N Rd + V Sd / V Rd ≤ 1.2, and bending proof: M Sd / M Rd + N Sd / N Rd ≤1. where: N Sd = Design value of the tensile load V Sd = Design value of the transverse load M Sd = Design value of the bending load --- N Rd = Design value of resistance to tensile load V Rd = Design value of resistance to transverse load M Rd = Design value of resistance to bending load

[0005] For a detailed description of the design verifications, reference is made to the GUIDELINE FOR EUROPEAN TECHNICAL APPROVAL of METAL ANCHORS FOR ANCHORING IN CONCRETE (ETAG 001, Annex C 1997).

[0006] Taking these design regulations into account, the expert can determine, based on specified design values ​​for tensile loads, shear loads, and bending loads, whether a planned fastening of fixtures to concrete or masonry using a group of anchors, referred to below as the "fastening group," is feasible, i.e., whether it complies with the design regulations. Typically, the expert uses a computer program to do this. Information representative of the tensile load, shear load, and, if applicable, a bending load is interactively entered. This program automatically calculates whether the planned fastening with the planned anchors complies with the design regulations. Common computer programs typically also indicate the extent to which the regulations are met.For example, it might turn out that the design specifications are significantly exceeded. In this case, the expert can modify the design, for example, using fewer anchors or using more cost-effective anchors with a smaller cross-section, and re-examine the design. Conversely, the computer program might indicate that a planned fastening does not meet the design specifications. In this case, the expert can provide additional anchors and / or use anchors with a larger diameter and re-examine the modified design.

[0007] The result is not satisfactory in all cases. For example, it can be difficult to select suitable anchors for areas close to edges. Especially in areas close to edges, the use of larger diameter anchors is often not possible, despite the higher costs, as this can cause problems with concrete edge failure. As a general rule, when designing the characteristic resistance to shear loads, concrete edge failure must be taken into account if the distance of the anchor from the edge is less than 60 times the diameter of the anchor. It is therefore clear that it would often be particularly advantageous to use an anchor with a smaller diameter. There is therefore a need for improved methods for attaching fixtures to masonry or concrete.

[0008] DE 2834200 discloses a fastening of a fixture to a mounting base using dowels whose dowel shafts are inclined by 30° relative to the surface of the mounting base. The inclined dowel shafts are located in different planes, and the angles are oppositely oriented. This fastening is proposed to counteract tensile forces perpendicular to the wall surface without requiring a frictional connection between the dowel shafts and the wall of the respective bore.

[0009] EP 2816171 A2 discloses a mounting plate for fastening a component to a wall, wherein the mounting plate has through holes for receiving fastening elements for fastening the mounting plate to the wall and a device for fastening the component to the mounting plate. At least two through holes are inclined relative to the mounting plate, and at least two through holes are orthogonal to the mounting plate. The angles of inclination of the inclined through holes are opposite.

[0010] DE 10 2004 033 472 A1 discloses a similar mounting plate designed for attaching an awning to a house wall using a thermal insulation system. The mounting plate includes anchor holes for inserting anchors to secure the mounting plate to the house wall. At least two of the anchors in the anchor plate are arranged diagonally apart.

[0011] CN 2 632 374 discloses an anchor plate that is attached to an anchoring base with bolts, with the two bolts arranged at an angle to each other. This V-shaped mounting is intended to increase the resistance to tensile forces acting on the plate.

[0012] GB 1 111 587 A discloses a load suspension device for ceiling fixtures subjected exclusively to tensile loads. The load suspension device is attached to an inclined anchor, the inclination of which serves to convert the tensile load into a shear force and transfer it to another bolt.

[0013] From the "Technical Manual of Fastening Technology for Building Construction and Civil Engineering" by HILTI (01-2014), characteristic resistances under shear load and tensile load for various anchors are disclosed, whereby the ratio of the characteristic resistances under shear load and tensile load is less than 1.1. SUMMARY OF THE INVENTION

[0014] The present invention is based on the object of providing an improved method for fastening attachments to masonry or concrete. This object is achieved by a method for dimensioning and carrying out the fastening of attachments to a mounting base according to claim 1 or claim 3. Advantageous further developments are specified in the dependent claims.

[0015] The invention provides a method for dimensioning and carrying out a fastening of attachments with a group of anchors to a fastening base formed by concrete or masonry.

[0016] The method is applied in cases where the ratio V Sd / Nsa of the design value of the shear load V Sd and the design value of the tensile load N Sd of at least one anchor of the anchor group is: V Sd / Nsa ≥ 0.3, preferably V Sd / Nsa ≥ 0.6 and particularly preferably V Sd / Nsa ≥ 1.0, and where for this anchor the characteristic resistances under shear load V Rk or under tensile load N Rk satisfy the following relationship: V Rk / N Rk ≤ 1,1 .

[0017] The characteristic resistances V Rk, N Rk each denote the lowest characteristic resistance resulting from the different failure modes to be taken into account in the design, for example V Rk,s , N Rk,s in the case of steel failure, particularly taking into account a possible lever arm, V Rk,c , N Rk,c in the case of concrete failure (concrete failure under tensile loading, concrete failure on the side facing away from the load or concrete edge failure under shear loading), etc.

[0018] According to the invention, the at least one anchor of the fastening group is inserted at an angle α anchor to the vertical of the surface of the fastening base in such a way that: α Anker = k * 3 4 * arctan V Sd / N Sd für N Sd > 0 , and α Anker = k * 67,5 ° für N Sd = 0 , with: 0.6 ≤ k ≤ 1.34, preferably 0.8 ≤ k ≤ 1.34, under the proviso that α anchor ≤ 75°, where α anchor is the angle of inclination of the anchor relative to the perpendicular to the surface of the base material. The angle of inclination α anchor is to be measured in the plane in which the shear load V Sd on which the design is based lies. Within this plane, the orientation of the angle α anchor is to be chosen such that the angle between the longitudinal axis of the anchor and the resulting load is smaller than with vertical installation. This means that one head of the anchor is tilted in the direction of the shear load V Sd compared to the vertical installation position.

[0019] According to the invention, when fastening an attachment to concrete or masonry, the anchors used for this purpose are inserted at least partially at an angle α anchor to the surface of the fastening base that deviates from 90°. This contradicts common practice, according to which anchors in concrete must always be inserted perpendicular to the concrete surface. The angle α anchor is selected according to the rule α anchor = k * ¾ * arctan (Vsa / Nsa). For the case N Sd = 0, i.e. the case of pure shear loading, α anchor = k * 67.5° applies. The parameter k can be selected in an interval from 0.8 to 1.34.

[0020] The invention is based on the finding that for a certain class of applications, an inclined anchor allows for better load-bearing capacity than an anchor installed perpendicular to the surface of the fastening base according to the prior art. Very good load-bearing capacities can be achieved if the angle α anchor is 75% of the angle at which the resultant tensile load and transverse load is to the surface normal of the surface of the fastening base, and this angle can be calculated using arctan (Vsa / Nsa). This corresponds to the case where the parameter k takes on the value 1. The range 0.8 ≤ k ≤ 1.34 defines a corridor around this preferred choice of angle, which also promises good load-bearing capacity. Within this range, however, the value of the parameter k must always be chosen so that α anchor ≤ 75°. Preferably, the parameter k should be chosen so that α anchor ≤ 70°.

[0021] Basically, steel failure limits the load level of the anchor. With regard to the resistance to tensile loading, the characteristic resistance N Rk,s of the anchor at steel failure represents an upper limit that cannot be exceeded regardless of the nature of the base material, the arrangement in the base material, etc. The value N Rk,s is derived from the equation N Rk , s = As * fuk , where As is the cross-sectional area of ​​the anchor and fuk is the characteristic tensile strength of the steel. Although steel is always assumed as the material of the anchor in this disclosure, it is understood that the invention is not limited to steel anchors.

[0022] However, the actual tensile strength may be reduced by failure mechanisms other than steel failure. Other possible failure mechanisms include concrete congealing and pull-out failure. For further details, reference is made to the GUIDELINE FOR EUROPEAN TECHNICAL APPROVAL of METAL ANCHORS FOR USE IN CONCRETE (ETAG 001, Annex C, 1997 edition), which is incorporated into this disclosure by reference.

[0023] The characteristic resistance under tensile loading N Rk relevant for the design is the lowest resistance that can result from the different failure mechanisms to be considered in the design.

[0024] With regard to the resistance to shear loading, V Rk,s the characteristic resistance with regard to steel failure without lever arm represents the upper limit. If there is no lever arm, it can be assumed that with regard to pure steel failure, the shear resistance can be a maximum of 0.5 times the tensile resistance of the anchor, which means that V Rk , s = 0,5 * N Rk , s = 0,5 * As * fuk .

[0025] However, if the shear load is applied via a lever arm, a "characteristic resistance to bending" must be considered. Further details on this and the corresponding calculation formulas can be found in the above-cited approval guideline ETAG 001. The failure mechanism in this case is still steel failure, so the resistance can still be referred to as V Rk,s, although in this case it is typically significantly lower than the maximum value of 0.5*As*fuk.

[0026] In addition to steel failure with and without lever, there are also other failure mechanisms in the case of shear loading, in particular concrete pry-out failure on the side facing away from the load (so-called pry-out failure) and concrete edge failure, which is usually considered when the anchor is less than ten times its installation depth or less than 60 times its diameter from the edge of the base material. Each of these failure mechanisms has a characteristic resistance, and the lowest resistance represents the relevant characteristic resistance V Rk for shear loading.

[0027] The inventor has systematically investigated various failure mechanisms of anchors in concrete for the case where, contrary to usual practice, the anchors are not installed perpendicular to the surface of the base material, but are inclined by an angle α anchor relative to the surface normal to the surface of the base material.

[0028] In practice, installation situations often arise in which anchor groups close to the edge are subjected to shear loads, such as when fixing balcony railings and parapets, or in which bending loads must be taken into account. The unsatisfactory results that repeatedly emerge in design services for customers prompted us to consider whether it is possible to make better use of anchor groups. After a detailed analysis of the design system according to ETAG_001, it was recognized that the capacity utilization of an anchor group can be improved by better utilizing the tensile capacity. To achieve this, it was considered to install the anchor not always perpendicular to the surface of the fixing base, but rather in the direction of the resulting load share of the tensile and shear load components to be transferred by the individual anchor.

[0029] By comparing the conical surfaces of the breakout body of an inclined anchor with the same anchorage depth measured perpendicular to the surface with the conical surface of a vertically installed anchor, it can be shown that the area of ​​the inclined anchor is at least the same, except for a small angular range, but is always larger with increasing angles than the breakout conical area of ​​the vertically installed anchor. Even limiting the area by a concrete edge does not lead to smaller areas. This analogy supports the assumption that an inclined anchor can achieve the same tensile capacity as a vertically installed anchor. Based on this, component tests and FEM simulations were able to confirm a better utilization of the anchors.

[0030] The inventor has found that there is a broad class of applications in which the load-bearing capacity can be improved, and in some cases significantly improved, compared to the load-bearing capacity with vertical installation of an anchor if the angle α anchor is selected according to the invention, i.e. if α anchor = k * ¾ * arctan (V Sd / N Sd ), with 0.8 ≤ k ≤ 1.34. Specifically, considerable improvements in the load-bearing capacity were found for applications in which V Rk / N Rk ≤ 1.1, i.e. in which the characteristic resistance under shear stress V Rk is smaller or only insignificantly larger than the characteristic resistance N Rk under tensile stress. The smaller the ratio V Rk / N Rk, the greater the improvements compared to conventional vertical installation.Improvements can be achieved in particular when compared to vertical installation if the anchorage depth hef measured perpendicular to the surface is kept constant, which means that the anchor must be selected to be longer by a factor of 1 / cos (α anchor ) than with vertical installation. In practice, however, this does not pose any problems, since a slightly longer anchor hardly increases the costs. However, it is much more problematic if anchors with a larger diameter have to be selected in order to comply with the design. These anchors are not only noticeably more expensive, but often cannot be used, especially in edge areas where design problems occur, because they lead to an increased risk of concrete edge failure (which ultimately leads to a lower value for V Rk).

[0031] However, this method only applies to cases where the design value for the shear load represents a significant proportion of the total load, specifically cases where V Sd / Nsa ≥ 0.3. For smaller shear loads, the increase in load-bearing capacity is either nonexistent or not so significant that it does not justify the additional effort of an inclined installation. Although the parameter k can generally be selected within the defined range, an additional condition is that k is always selected sufficiently small so that: α anchor ≤ 75°, preferably ≤ 70°, so as not to unduly complicate installation.

[0032] There are a number of typical situations in which the ratio V Rk / N Rk becomes small, and in particular ≤ 1.1, and in which the method of finding is advantageously applied.

[0033] A typical application is fastenings close to the edge, where the characteristic resistances of the transverse load are usually significantly smaller than the characteristic resistances for tensile load, i.e. V Rk <N Rk .

[0034] Another typical application is fastenings without edge influence with large embedment depths, where the pure steel failure is the decisive design limit, and therefore V Rk,s = 0.5* N Rk,s in good nutrition applies, so that in any case V Rk <N Rk .

[0035] Bending stress can also significantly reduce the load-bearing capacity. As mentioned above, bending stress with a lever arm leads to a reduced value for V Rk , and thus also regularly leads to a situation with V Rk <N Rk .

[0036] Bending stresses on the anchor must be taken into account if there is a non-compressive intermediate layer between the fixture and the base material, or if there is a gap or distance between the fixture and the base material. Bending stresses must also be taken into account if the fixture itself is not compressive, i.e., if it is not made of metal or concrete, but rather of wood, for example. Finally, bending stresses regularly play a role if the hole clearance of the connection is too large. With increasing distance from the load introduction into the anchor in the fixture to the joint between the fixture and the base material, the bending stress increases for the same effect on the fixture.

[0037] Due to the inclined installation, the anchor is, in simple terms, subject to greater tensile loads than a vertically installed anchor under the same load situation. The method according to the invention envisages, as an extreme case at k = 1.33, the situation in which the anchor assumes the same inclination to the surface of the mounting base as the total load, i.e., the resultant of the shear load and the tensile load. In this case, the anchor would only be subjected to tensile loads.

[0038] However, according to the inventor's calculations, the best results are generally not obtained when the longitudinal axis of the anchor is aligned parallel to the resulting force, but when the angle α anchor is selected to be smaller than the angle of the resulting load relative to the surface normal to the surface of the fastening base. Therefore, in preferred embodiments, k ≤ 1.2, preferably k ≤ 1.15 and particularly preferably k ≤ 1.1. This is at least the case when pressures can be transmitted via the joint between the attachment and the fastening base. In installation positions with k ≤ 1.2, the anchor is predominantly subjected to tensile stress (relative to the axis of the anchor, not relative to the surface normal to the fastening base), but also slightly subjected to shear force. However, the shear load is absorbed directly by the anchor being applied to the borehole wall in the attachment via pressures.By redistributing the reaction forces, the attachment is pressed against the mounting base. In preferred embodiments, therefore, k ≤ 1.2, preferably k ≤ 1.15, and particularly preferably k ≤ 1.1. In an advantageous embodiment, the at least one anchor is guided through a bore in the attachment, wherein the diameter of the bore exceeds the diameter of the anchor in a section in which it is accommodated in the bore in the assembled state by less than 22%, preferably less than 12%. With such a small amount of play of the anchor in the bore of the attachment, the transverse load can be effectively absorbed by compression.

[0039] A different assessment is required in the case where there is a gap between the fixture and the base material containing a non-compression-resistant material. An example of a non-compression-resistant material could be a non-compression-resistant plaster layer, wood, an insulation layer, or even simply air. In this case, the parameter k is preferably chosen to be larger, so that k ≥ 1.1, preferably k ≥ 1.2, and particularly preferably k ≥ 1.25. The ideal case could be k = 1.33, according to which the anchor is aligned parallel to the direction of the total load, so that the anchor is only subjected to tensile stress (relative to its own axis, not to the surface of the base material!).

[0040] Although the relationship described above defines special inclination angles α anchor that promise a particularly pronounced increase in load-bearing capacity, in practice it is not necessary to calculate the appropriate angle individually for each application. Instead, significant progress can be achieved compared to the current method if, as an alternative to the vertical installation, only a possible alternative standard installation angle α anchor is considered, i.e. one that represents an alternative to the currently only valid installation angle of 0°. According to the inventor's investigations, this alternative standard installation angle α anchor should be between 35° and 55°, preferably between 40° and 50°, and particularly preferably approximately 45° to the perpendicular to the surface of the fastening base, because this can already achieve a significant improvement in a large number of applications.In this simplified version of the method, the alternative standard mounting bracket is considered at least if the ratio V Sd / N Sd of the design value of the shear load V Sd and the design value of the tensile load N Sd of at least one anchor in the anchor group is: V Sd / N Sd ≥ 0.8 and preferably V Sd / N Sd ≥ 1.0, and if for this anchor the characteristic resistances under shear load V Rk or under tensile load N Rk satisfy the following relationship: V Rk / N Rk ≤ 1.1. By limiting the method to this one alternative standard mounting bracket, the method is considerably simplified in terms of both installation and design. At the same time, in many cases the load-bearing capacity can be considerably increased using this alternative standard mounting bracket.

[0041] The inventor carried out pull-out tests specifically for an installation angle of 45° and found that this allows considerable improvements to be achieved, both for the case of a resultant load at this 45° angle (i.e. V Sd = N Sd ), and for the case of a pure shear force (Nsa = 0). Especially in the case of installation close to the edge, the resistance with regard to the case of a pure shear force could be increased by a factor of three compared to a vertically installed anchor with the same effective anchorage depth hef, i.e. measured perpendicular to the surface of the fixing base. For a force that is also at a 45° angle to the surface normal (i.e. V Sd = N Sd ), the failure load could even be increased by a factor of four. It is noteworthy that the tensile strength perpendicular to the concrete surface - again with the same effective anchorage depth - was comparable to that with vertical installation.To achieve the same effective anchorage depth hef, the anchor installed at a 45° angle must be longer by a factor of 1.41 than the vertically installed anchor. However, the significant increases in load-bearing capacity are by no means solely due to the longer anchor length. Instead, the tensile experiments show that, even with the same anchor length, installation at an angle of 45° to the surface normal regularly leads to significant improvements in load-bearing capacity, as long as the shear load V Sd is similar to or greater than the tensile load N Sd attributable to the anchor.

[0042] Within the framework of the simplified procedure, whenever it is suspected that inclined installation with the alternative standard mounting angle could result in an improvement over vertical installation, a design calculation could be carried out to determine whether the load-bearing capacities increase, and if so, by how much, in order to decide whether to use this alternative standard mounting angle. In advantageous embodiments, this alternative standard mounting angle would be automatically considered and suggested to the user.

[0043] In preferred embodiments, the characteristic resistances under transverse stress V Rk or under tensile stress N Rk satisfy the following relationship: V Rk / N Rk ≤ 1.0, preferably ≤ 0.8, and particularly preferably ≤ 0.6.

[0044] In anchor groups, i.e., attachments secured with multiple anchors, the load transfer can also be distributed by arranging some of the anchors at an angle, while the others are arranged vertically. By appropriately selecting the size of the through holes in the attachment, the tensile load can be assigned to the vertically arranged anchors and the transverse load to the inclined anchors. This allows for further optimization of the connection in anchor groups.

[0045] For example, the anchor mentioned, which is installed at the angle α anchor defined above, can be an anchor closer to the edge within the anchor group, and the anchor group can contain an anchor further away from the edge, which is installed perpendicular to the surface of the fixing base. The reasoning behind this is that, according to the applicable design regulations, an anchor close to the edge must be suitable for carrying the full shear load, and the characteristic resistance to shear stress V Rk is lower in areas close to the edge than in areas far from the edge. Since the anchor inclined at the angle α anchor offers significantly greater resistance to shear loads, this criterion can be met more easily within the scope of the invention than in the prior art. In contrast, the requirements for the characteristic resistance to shear stress V Rk for the anchor far from the edge are less stringent, so that it can be installed vertically as usual.In the present disclosure, an anchor is referred to as "near the edge" if it is less than ten times the effective, ie vertical, anchorage depth hef, preferably less than five times the effective manufacturing depth from the edge of the fastening base.

[0046] In an advantageous development, the anchor inserted at the above-defined angle α is an anchor further from the edge within the anchor group, and the anchor group contains an anchor closer to the edge, which is accommodated in a slotted hole in the attachment and inserted perpendicular to the surface of the mounting base. In the context of the present disclosure, a "slotted hole" is understood to mean a hole that is sufficiently large that it can be assumed that an anchor accommodated therein will not experience any significant transverse load. This can be a slotted hole in the narrower sense of an elongated hole, but also a round hole with a sufficiently large diameter. In this embodiment, the anchor closest to the edge is thus inserted vertically and is therefore less suitable for withstanding transverse loads.However, since this anchor near the edge is housed in a slotted hole, it is subjected only to tensile forces, not shear forces, and therefore the latter need not be considered in the design. The anchor far from the edge has to bear correspondingly higher shear forces. However, the inclined installation is advantageous for this.

[0047] The method described above is applicable to any anchor, some of which are briefly mentioned below. In the simplest case, the at least one anchor can be formed by a one-piece anchor comprising the following: a load introduction region arranged in the region of a leading end of the anchor and suitable for introducing a load into the fastening base, a shank section, a section or an element for fixing the anchor in the region of a trailing end to the fixture, and a power drive for setting the anchor.

[0048] The one-piece anchor can, for example, be formed by a conventional concrete screw. In this case, the load introduction area is formed by a concrete thread, the force drive is formed by a screw head, and the section for securing the anchor to the fixture is also formed by the screw head. However, the one-piece anchor can also be formed by an expansion anchor or undercut anchor.

[0049] In other embodiments, the at least one anchor is formed by a two-part system comprising an anchor sleeve and a tensioning element, wherein the anchor sleeve is suitable for introducing a load into the fastening base and has an internal thread, and wherein the tensioning element a shaft portion having an external thread in the region of its leading end with which it can be screwed into the internal thread of the anchor sleeve to transmit a load, a portion or element for securing the shaft portion of the tensioning element to the attachment in the region of a trailing end, and a power drive for screwing the tensioning element into the anchor sleeve.

[0050] The said section for fixing the anchor or the tensioning element to the attachment part can be formed by a screw head, which at the same time forms the said power drive.

[0051] Alternatively, the at least one anchor is formed by a two-part system comprising an anchor sleeve and a tensioning element, wherein the anchor sleeve is suitable for introducing a load into the fastening base, and wherein the tensioning element a shaft portion having in the region of its leading end a stop element, in particular a screw head or a screwed-on nut, against which the anchor sleeve can strike in order to transmit a load, and comprising a portion or an element for fixing the shaft portion of the tensioning element to the attachment part in the region of a trailing end.

[0052] The advantage of this design is that the anchor sleeve does not need to be provided with an internal thread, which reduces manufacturing costs.

[0053] Preferably, a thread is provided at the trailing end of the anchor or tensioning element, and said element for fixing the anchor or tensioning element is formed by a nut which can be screwed onto the thread against the attachment part.

[0054] In an alternative embodiment, the anchor is formed by a multi-part system comprising: a first anchor sleeve which is suitable for introducing a load into the fastening base, a second anchor sleeve which is suitable for introducing a load into the attachment part, and an elongated tensioning element which is suitable for being passed through the second anchor sleeve and inserted into or passed through the first anchor sleeve, and which is suitable for axially tensioning the first and the second anchor sleeve such that the first and the second anchor sleeve form opposing bond stresses in the fastening base or attachment part.

[0055] Here, the statement that the elongated tensioning element is suitable for "passing" through the two anchor sleeves is not intended to suggest that the anchor sleeves are necessarily inserted before the tensioning element. Rather, even in this embodiment, it is possible for the tensioning element to have a stop element, in particular a screw head or a threaded nut, near its leading end, against which the anchor sleeve can strike to transfer a load. In this case, the elongated tensioning element is first inserted into the borehole, and the anchor sleeves are subsequently placed or "threaded" onto the tensioning element and inserted into the borehole sliding over the elongated tensioning element, whereby the elongated tensioning element, although itself at rest, is "passed" through the anchor sleeves.

[0056] In an advantageous further development, the measurement is carried out using a computer program product, wherein the computer program product comprises a plurality of instructions which, when executed on a computer system, carry out the following steps: Output of a Graphical User Interface (GUI) via a display device, wherein the GUI has input fields that allow a user to enter information regarding a planned fastening of an attachment to a concrete or masonry base using a group of anchors, wherein this information represents at least a design value of the transverse load V Sd and a design value of the tensile load N Sd of at least one anchor in the anchor group, or these design values ​​V Sd and N Sd are derivable from this information, wherein the GUI is further configured to indicate whether the planned fastening complies with predetermined design regulations, wherein the computer program is configured to, at least in cases where the ratio V Sd / N Sd of the design value of the transverse load V Sd and the design value of the tensile load N Sd of an anchor in the anchor group is: V Sd / N Sd ≥ 0.3, preferably V Sd / N Sd ≥ 0.6 and particularly preferably V Sd / N Sd ≥ 1.0,and in which the characteristic resistances under shear load V Rk or under tensile load N Rk of this anchor satisfy the following relationship: V Rk / N Rk ≤ 1,1, a calculation of the design of this anchor of the anchor group for an installation with an angle α anchor to the perpendicular to the surface of the base material, for which the following applies: , α Anker = k * 3 4 * arctan V Sd / N Sd für N Sd > 0 , and α Anker = k * 67,5 ° für N Sd = 0 , with: 0.8 ≤ k ≤ 1.34, provided that α anchor ≤ 75°, where α anchor is the angle of inclination of the anchor with respect to the perpendicular to the surface of the base material, the angle of inclination α anchor being to be measured in the plane in which the shear load Vsa underlying the design is located, and the result of the design being output.

[0057] Alternatively, a computer program product may be used that is directed to the simplified method described above, in which, in addition to the usual mounting of the anchors at 0°, an alternative standard mounting angle is considered. This computer program comprises a plurality of instructions that, when executed on a computer system, perform the following steps: Outputting a Graphical User Interface (GUI) via a display device, wherein the GUI has input fields that allow a user to enter information regarding a planned fastening of an attachment to a fastening base made of concrete or masonry using a group of anchors, wherein this information represents at least one design value of the transverse load V Sd and one design value of the tensile load N Sd of at least one anchor in the anchor group, or these design values ​​V Sd and N Sd are derivable from this information, wherein the GUI is further configured to indicate whether the planned fastening complies with predetermined design regulations, wherein the computer program is configured to carry out a calculation of the design of this anchor of the anchor group for an installation with an angle α anchor to the perpendicular to the surface of the fastening base, for which 35° ≤ α anchor ≤ 55°, preferably 40° ≤ α anchor ≤ 50°,Particularly preferably, 43° ≤ α anchor ≤ 48°, whereby the angle of inclination α anchor is to be measured in the plane in which the shear load Vsa underlying the design lies, and the design result is to be output. In this simplified embodiment, the angle α anchor is a predetermined angle that does not need to be individually calculated depending on the actual design values ​​of the shear load V Sd and the tensile load N Sd.

[0058] In the advantageous embodiment, the input fields of the GUI allow the user to enter information regarding one or more of the following characteristics: type or nature of the fastening base; type, size, shape, material of an anchor plate; design values ​​regarding tensile force, shear force, torsional moment, and / or bending moment; type and / or dimension of the anchor.

[0059] In an advantageous further development, the computer program product is designed to first calculate a design for an anchor installed perpendicular to the base material and, in the event that this anchor does not meet the design requirements, to alternatively propose an inclined installation that meets the design requirements. BRIEF DESCRIPTION OF THE CHARACTERS

[0060] Fig. 1 shows a schematic sectional view illustrating the fastening of an attachment using two inclined concrete anchors. Fig. 2 shows a sectional view illustrating the fastening of an attachment in a near-edge area to concrete, using two vertically placed anchors. Fig. 3 shows the same situation as Fig. 2 , in which the anchor closer to the edge is set inclined relative to the surface normal. Fig. 4 shows the same situation as Fig. 2, in which the anchor closest to the edge is arranged in a slotted hole in the fixture, and the anchor farther from the edge is inclined to the surface normal. Fig. 5 shows a fastening of a fixture using two inclined anchors subjected only to tensile loads. Fig. 6 shows a screenshot of a GUI of a computer program suitable for performing designs according to the inventive method. Figs. 7-11 show various anchors that can be used in the method according to embodiments of the invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0061] Further advantages and features of the invention will become apparent from the following description, in which the invention is described using an exemplary embodiment with reference to the accompanying drawings.

[0062] Fig. 1shows a sectional view of a fastening of an attachment 10 to a concrete base 12 by means of two anchors 14, which in the embodiment shown are formed by schematically illustrated concrete screws. In the embodiment of Fig. 1 The attachment 10 is formed by a metal plate, such as could be used, for example, to attach a balcony railing or the like. However, the invention is not limited to specific attachments. Instead, any attachment 10, particularly those made of concrete, can be attached to the mounting base 12.

[0063] The attachment 10 is subjected to a transverse load with a design value V Sd and a tensile load N Sd , which are evenly distributed between the corresponding loads V Sd, 1 , N Sd, 1 with respect to the upper anchor and V Sd, 2 , N Sd, 2 with respect to the lower anchor, ie the following applies: V Sd, 1 = V Sd,2 = ½ V Sd , N Sd, 1 = N Sd, 2 = ½ N Sd . The resulting or total load is inclined at an angle of arctan (V Sd / N Sd ) = 40° to the surface normal.

[0064] In the embodiment of Fig. 1 The anchors 14 are not set perpendicular to the surface of the mounting base 12, as is usual in the prior art. Instead, they are set at an angle α anchor of 30°, i.e., ¾ of the angle of the actual resulting load. This allows a significantly higher load to be carried than with a vertical installation. Fig. 1The effective installation depth hef is also shown. In this case, the effective installation depth hef does not correspond to the length of the anchor 14, but rather to its vertical projection, or in other words, the length of the anchor 14 multiplied by cos(α anchor ).

[0065] Fig. 2 shows a cross-sectional view of a fastening of an attachment 10 using two anchors 14 in a near-edge area of ​​a concrete base 12. In this case, according to the applicable design regulations, the near-edge anchor must be designed to support the entire shear load corresponding to the design value of the shear load V Sd, i.e., V Sd,2 = V Sd . This is sometimes difficult to achieve in practice because small edge distances reduce the characteristic resistance to shear loading V Rk.

[0066] A solution to these difficulties is in Fig. 3shown, in which, in the otherwise identical situation, the anchor closest to the edge is inserted at an angle of α anchor = ¾ * arctan (V Sd,2 / N Sd ), but has the same setting depth relative to the surface of the fixing base 12 as the vertically set anchor 14 of Fig. 2 Since in this case no shear forces are applied to the anchor furthest from the edge, there is nothing to prevent this from being designed as in Fig. 3 shown, set vertically in the usual way.

[0067] Fig. 4 shows an alternative variant, the situation of Fig. 2 In this variant, the anchor 14 closest to the edge is placed in a slotted hole 16, so that no part of the shear load V Sd is allocated to this anchor during the design, while the tensile loads are distributed evenly, ie N Sd,2 = N Sd,2 = ½ * N Sd . The inclined anchor 14 far from the edge in Fig. 4Compared to this comparatively high transverse load V Sd,1 = V Sd, it has an improved load-bearing capacity than a vertically installed anchor.

[0068] Finally, Fig. 5 a variant in which there is no pressure-resistant material between the attachment part 10 and the mounting base 12. In Fig. 5 A gap is shown, which in practice can be formed by a non-compression-resistant material, such as an insulating material or a non-compression-resistant plaster. In the arrangement of Fig. 5the design values ​​of the transverse load V Sd and tensile load N Sd are distributed evenly among the individual anchors 14, i.e. V Sd, 1 = V Sd, 2 = ½ * V Sd , and N Sd, 1 = N Sd, 2 = ½ * N Sd . In this embodiment, α anchor is selected such that it corresponds to arctan (Vsa / Nsa), i.e. the anchors 14 are each arranged parallel to the resulting force and are therefore only subjected to tensile loads (relative to their own longitudinal axis). In the general representation, this corresponds to the case k = 1.33 for the angle α anchor.

[0069] The measurement described above can be carried out using a computer program product that contains a plurality of instructions that, when executed on a computer system, output a GUI via a display device, as exemplified in Fig. 6is shown. Such computer programs are generally known and common and help the user determine whether a planned application, in this case the fastening of a fixture 10 to a concrete base 12, complies with the design regulations. For this purpose, the GUI contains input fields that allow the user to enter information regarding a variety of characteristics, for example, a field 20 for specifying the base (in this case, concrete), a field 22 for entering information regarding the type, size, shape, and material of an anchor plate, fields 24 for entering design values ​​of the loads, in particular tensile force, shear force, torsional moment, and bending moment, and a field 26 for specifying the type and dimensions of the anchor 14.

[0070] On the right side of the GUI of Fig. 6The results of the design calculation are displayed according to the entered values ​​and parameters. As can be seen in the example screenshot, the planned fastening meets the design requirements with regard to all failure mechanisms considered here with regard to tensile loading (steel failure, pull-out, concrete contusion). Furthermore, the design requirements with regard to shear loading with regard to steel failure without lever arm and with regard to concrete contusion are also met, but not with regard to failure with regard to concrete edge failure. Here, the shear loading exceeds the resistance under shear loading with regard to the concrete edge contusion failure mechanism by approximately 20%, and the interaction condition is even exceeded by 60%. These results refer to the design for the usual installation, in which the anchors 14 are set perpendicular to the surface of the fastening base 12.

[0071] The computer program can also suggest designs where the anchor is not set vertically, but at an angle α anchor to the surface normal of the fastening base 12. In the embodiment shown, the program automatically suggests a design for an inclined installation if certain criteria are met. One such criterion may be that the design specifications cannot be met with a vertical installation of the anchor. Another criterion may be that a significantly better load-bearing capacity can be expected with an inclined installation, for example in cases where a limit with regard to the ratio Vsa / N Sd is exceeded, or a limit for V Rk / N Rk is not met. In some cases it is advantageous to consider a more load-bearing construction, even if the design specifications for the planned fastening can also be met with a vertical installation.For example, this may prompt the user to consider mounting with anchors of smaller cross-section. In some embodiments, the computer program can also suggest suitable, usually most cost-effective, anchors that can be used to implement the fastening while taking advantage of the possibility of inclined mounting.

[0072] In the Fig. 6 The screenshot shows that at an anchor angle α of 34.23°, the design requirements are not yet met, but the load-bearing capacity is already significantly better than with vertical installation. At an angle of 38°, however, all design requirements are met.

[0073] It is understood that there are currently no officially recognized design rules for inclined installation of anchors in concrete. If, in connection with Fig. 6When reference is made to "design regulations," this refers to the design regulations expanded to include the possibility of inclined installation. The inventor's research clearly indicates that this can produce significantly better load-bearing capacities in a wide variety of applications than is currently possible.

[0074] In a simplified embodiment of the computer program, it can be provided to only carry out a design for a predetermined alternative standard mounting angle, for example a mounting angle of 45°. The design can be carried out on request, i.e. in response to a user input, and / or automatically. Automatic execution can be considered, for example, if, due to the installation position (near the edge, lever arm, etc.) and the loads on which the design is based, in particular tensile force and shear force, there are indications that the load-bearing capacity would be increased if the installation were carried out using the alternative standard mounting angle compared to vertical installation. It is also possible that the design calculation is always carried out for installation using the alternative standard mounting angle and the result is displayed, or at least displayed if it promises an improved load-bearing capacity.

[0075] The method described above is not limited to a specific type of anchor. Rather, in the present disclosure, the term "anchor" is to be understood broadly and can be formed by a one-piece anchor in the narrowest sense, as well as by two- or three-piece systems, which are briefly described below.

[0076] In the Fig. 1 to 5 The anchors 14 are each formed by concrete screws. Such concrete screws are known in the art and typically have a self-tapping concrete thread that forms a load introduction area, a shank portion, and a head that serves both as a power drive for setting the anchor and for securing the attachment 10.

[0077] Fig. 7shows another example of a one-piece anchor, namely an undercut anchor that is inserted at an angle into the mounting base 12. At its trailing end, the undercut anchor has a metric thread 28, onto which a washer 30 is placed, and which is tightened against the attachment 10 with a nut 32.

[0078] Fig. 8 shows a two-part anchor comprising an anchor sleeve 34, which also provides an undercut. The anchor sleeve 34 is in Fig. 8 shown partially in section, and has a metric internal thread into which a threaded rod 36 is screwed. A washer 30 and a nut 32 are arranged at the trailing end of the threaded rod 36.

[0079] Fig. 9shows a further example of a two-part anchor, comprising an anchor sleeve 40 with a self-tapping external thread 38. Inside the anchor sleeve 40, a metric internal thread is formed, into which, as in Fig. 8 a threaded rod 36 is screwed in. A washer 30 and a nut 32, which are tightened against the attachment 10, are used to fasten the attachment 10 to the mounting base 12. The threaded rod 36 represents an example of a "tensioning element" mentioned above. The anchor sleeve 40 also has a power drive (not shown in the figure) with which it can be screwed into the concrete of the mounting base 12.

[0080] Fig. 10shows an anchor 14 according to a related embodiment, which is formed by a three-part system comprising a first threaded sleeve 40 of the type described above and a second threaded sleeve 42 which does not contain an internal thread. In the illustration of Fig. 10 The attachment 10 is also a concrete part that is joined to the mounting base 12 using the anchor 14. Examples of such concrete attachments are bridge caps or similar.

[0081] As in Fig. 10As shown, the first threaded sleeve 40 is screwed into the fastening base 12, while the second anchor sleeve 42 is screwed into the attachment 10. The tensioning element here is again a threaded rod 36, which is guided through the (internally thread-free) second anchor sleeve 42 and screwed into the internal thread in the first anchor sleeve 40. When the nut 32 is tightened, the first and second anchor sleeves 40, 42 are axially tensioned such that the first and second anchor sleeves 40, 42 form opposing bond stresses in the fastening base 12 and the attachment 10, respectively.

[0082] Fig. 11 shows a side view and a sectional view of an alternative two-part system, which is similar to the system of the anchor 14 of Fig. 9is fundamentally similar. The difference is that the anchor sleeve 40 in this case has no internal thread, and the tensioning element in this case is formed by a screw 44, which is to be inserted upside down, i.e. with the head 46 facing forward, into the borehole before the anchor sleeve 40 is screwed in. The head 46 is then located at the leading end of the tensioning element 44 and forms a stop element against which the anchor sleeve 40 can strike in order to transfer a load. This variant is advantageous in that the anchor sleeve 40 can be designed without an internal thread. Even for a three-part system as in Fig. 10 As shown, such a clamping element 44 can be used with a stop element 46 at the leading end, wherein again the clamping element 44 is first introduced into the borehole, and then the first and second sleeves 40, 42 are guided over the clamping element and screwed into the fastening base 12 or the attachment part 10.

[0083] It should be noted that all embodiments with concrete threads, which transmit the load to be transferred into the concrete via a composite mechanism, can also be designed with a shear connector, which transfers the load into the concrete via a composite mass. Furthermore, it should be noted that the previously described embodiments are to be considered purely exemplary and not limiting the invention, and that the described features can be significant in any combination. List of reference symbols

[0084] 10Attachment 12Mounting base 14Anchor 16Elongated hole 20, 22, 24, 26GUI fields 28Metric thread 30Washer 32Nut 34Anchor sleeve 36Threaded rod 38External thread 40First anchor sleeve 42Second anchor sleeve 44Screw 46Head

Claims

1. Method for rating and carrying out an attachment of mounted parts (10) on a mounting base (12), which is formed by concrete or masonry, with a group of anchors (14), with the following steps: determining a rating value of the transverse load VSd and a rating value of the tensile load NSd, for at least one anchor (14) in the anchor group, wherein for the case that for the ratio VSd / Nsa of the rating value of the transverse load VSd and the rating value of the tensile load NSd of at least this anchor (14) in the anchor group the following applies: VSd / Nsa ≥ 0.3, preferably VSd / Nsa ≥ 0.6 and particularly preferably VSd / NSd ≥ 1.0, and that for this anchor the characteristic resistances for transverse loading VRk and for tensile loading NRk, respectively, fulfil the following relationship: VRk / NRk ≤ 1.1, wherein all values for VSd, NSd, VRk and NRk relate to the case of the installation of the anchor (14) perpendicular to the surface of the mounting base (12), for this anchor (14) it is checked whether the rating value of the load action exceeds the rating value of the resistances of this anchor with respect to at least one failure mechanism, for the case that this anchor (14) is inserted inclined at an angle αAnchor to the surface normal to the surface of the mounting base (12) in such a way that the following applies: α Anchor = k * 3 / 4 * arctan V Sd / N Sd for N Sd > 0 , and α Anchor = k*6 7.5 ° for N Sd = 0 , where: 0.6 ≤ k ≤ 1.34, preferably 0.8 ≤ k ≤ 1.34, with the proviso that αAnchor ≤ 75°, wherein the angle of inclination αAnchor is to be measured in the plane in which the transverse load VSd on which the rating is based lies and within this plane the orientation of the angle is to be selected in such a way that the angle between a longitudinal axis of the anchor and a resulting load becomes smaller than in the case of an installation perpendicular to the surface of the mounting base, and if this is not the case, the at least one anchor (14) of the anchor group is inserted at the angle αAnchor.

2. Method according to Claim 1, wherein k ≤ 1.2, preferably k ≤ 1.15 and particularly preferably k ≤ 1.1, and / or wherein k ≥ 0.85, preferably k ≥ 0.9.

3. Method for rating and carrying out an attachment of mounted parts (10) on a mounting base (12), which is formed by concrete or masonry, with a group of anchors (14), with the following steps: determining a rating value of the transverse load VSd and a rating value of the tensile load NSd, for at least one anchor (14) in the anchor group, wherein for the case that for the ratio VSd / Nsa of the rating value of the transverse load VSd and the rating value of the tensile load NSd of at least this anchor (14) in the anchor group the following applies: VSd / NSd ≥ 0.8 and preferably VSd / Nsa ≥ 1.0, and that for this anchor the characteristic resistances for transverse loading VRk and for tensile loading NRk , respectively, fulfil the following relationship: VRk / NRk ≤ 1.1, wherein all values for VSd, NSd, VRk and NRk relate to the case of the installation of the anchor (14) perpendicular to the surface of the mounting base (12), for this anchor (14) it is checked whether the rating value of the load action exceeds the rating value of the resistances of this anchor with respect to at least one failure mechanism, for the case that this anchor (14) is inserted inclined at an angle αAnchor of between 35° and 55°, preferably of between 40° and 50°, and particularly preferably of about 45° to the surface normal to the surface of the mounting base (12), wherein the angle of inclination αAn-chor is to be measured in the plane in which the transverse load VSd on which the rating is based lies and within this plane the orientation of the angle is to be selected in such a way that the angle between a longitudinal axis of the anchor (14) and a resulting load becomes smaller than in the case of an installation perpendicular to the surface of the mounting base (12), and if this is not the case, the at least one anchor (14) of the anchor group is inserted at the angle αAnchor.

4. Method according to one of Claims 1 to 3, wherein the characteristic resistances in the case of transverse loading VRk and in the case of tensile loading NRk , respectively, fulfil the following relationship: VRk / NRk ≤ 1.0, preferably ≤ 0.8, and particularly preferably ≤ 0.6, and / or wherein the at least one anchor (14) is guided through a bore in the mounted part (10), wherein the diameter of the bore exceeds the diameter of the anchor (14) by less than 22%, preferably less than 12%, in a section in which it is accommodated in the bore in the installed state.

5. Method according to one of Claims 1 to 3, wherein said anchor (14) is an anchor closer to the edge within the anchor group, and the anchor group contains an anchor further away from the edge, which is inserted perpendicular to the surface of the mounting base (12), and / or wherein said anchor (14) is an anchor further away from the edge within the anchor group, and the anchor group contains an anchor (14) closer to the edge, which is accommodated in an elongate hole (16) in the mounted part and is inserted perpendicular to the surface of the mounting base (12).

6. Method according to one of Claims 1, 2, 4 or 5, wherein the rating of this mounting is carried out with the aid of a computer program product, wherein the computer program product comprises a plurality of instructions which, when executed on a computer system, carry out the following steps: outputting a graphical user interface (GUI) via a display device, wherein the GUI has input fields (20-26) which allow a user to input information relating to a planned attachment of a mounted part on a mounting base made of concrete or masonry with a group of anchors, wherein this information represents at least a rating value of the transverse load VSd and a rating value of the tensile load NSd of at least one anchor (14) in the anchor group, or these rating values VSd and NSd can be derived from this information, wherein the values VSd and NSd relate to the case of mounting the anchor (14) perpendicular to the surface of the mounting base (12), wherein the GUI is furthermore configured to display whether the planned attachment complies with predetermined rating rules, wherein the computer program is configured, at least in cases in which - for the ratio VSd / Nsa of the rating value of the transverse load VSd and the rating value of the tensile load NSd of an anchor (14) in the anchor group the following applies: VSd / Nsa ≥ 0.3, preferably VSd / Nsa ≥ 0.6 and particularly preferably VSd / Nsa ≥ 1.0, and - in which the characteristic resistances for transverse loading VRk and for tensile loading NRk , respectively, of this anchor (14), in each case related to the case of the installation perpendicular to the surface of the mounting base (12), fulfil the following relationship: VRk / NRk ≤ 1.1, a calculation of the rating of this anchor of the anchor group is carried out for an installation at an angle αAnchor to the surface normal to the surface of the mounting base (12), for which the following applies: α Anchor = k * 3 / 4 * arctan V Sd / N Sd for N Sd > 0 , and α Anchor = k*6 7.5 ° for N Sd = 0 , where: 0.8 ≤ k ≤ 1.34, with the proviso that αAnchor ≤ 75°, wherein αAnchor is the angle of inclination of the anchor (14) with respect to the surface normal to the surface of the mounting base (12), wherein the angle of inclination αAnchor is to be measured in the plane in which the transverse load VSd on which the rating is based lies and within this plane the orientation of the angle αAnchor is to be selected in such a way that the angle between a longitudinal axis of the anchor (14) and a resulting load becomes smaller than in the case of an installation perpendicular to the surface of the mounting base (12), and the result of the rating is output.

7. Method according to one of Claims 3 to 5, wherein the rating of this mounting is carried out with the aid of a computer program product, wherein computer program product comprises a plurality of instructions which, when executed on a computer system, carry out the following steps: outputting a graphical user interface (GUI) via a display device, wherein the GUI has input fields (20-26) which allow a user to input information relating to a planned attachment of a mounted part on a mounting base made of concrete or masonry with a group of anchors, wherein this information represents at least a rating value of the transverse load VSd and a rating value of the tensile load NSd of at least one anchor (14) in the anchor group, or these rating values VSd and NSd can be derived from this information, wherein the values VSd and NSd relate to the case of mounting the anchor (14) perpendicular to the surface of the mounting base (12), wherein the GUI is furthermore configured to display whether the planned attachment complies with predetermined rating rules, wherein the computer program is configured to carry out a calculation of the rating of this anchor of the anchor group for an installation at an angle αAnchor to the surface normal to the surface of the mounting base (12), for which the following applies: 35° ≤ αAnchor ≤ 55°, preferably 40° ≤ αAnchor ≤ 50°, particularly preferably 43° ≤ αAnchor ≤ 48°, wherein the angle of inclination αAnchor is to be measured in the plane in which the transverse load VSd on which the rating is based lies and within this plane the orientation of the angle is to be selected in such a way that the angle between a longitudinal axis of the anchor (14) and a resulting load becomes smaller than in the case of an installation perpendicular to the surface of the mounting base (12), and the result of the rating is output.

8. Method according to Claim 6 or 7, wherein the input fields of the GUI allow the user to input information relating to one or more of the following features: type or nature of the mounting base (12); type, size, shape and material of an anchor plate (10), rating values relating to tensile force, transverse force, torsional moment, and / or bending moment, type and / or dimension of the anchor, and / or which is configured firstly to calculate a rating for an anchor (14) set perpendicular to the mounting base (12), and for the case that this does not fulfil the rating rules, alternatively to propose an inclined installation which fulfils the rating rules.