GB2157465A

GB2157465A - Apparatus for the determination of permissible loads upon dowels

Info

Publication number: GB2157465A
Application number: GB08508087A
Authority: GB
Inventors: Eugen Harald Zimmermann; Gunter Fuhrmann; Manfred Schwenzer
Original assignee: Upat Max Langensiepen KG
Current assignee: Upat Max Langensiepen KG
Priority date: 1984-04-09
Filing date: 1985-03-28
Publication date: 1985-10-23
Also published as: FR2562690A3; DE8411086U1; GB8508087D0; FR2562690B3

Abstract

The apparatus comprises a primary data-setting device (1) provided with at least two polar logarithmic scales (A, B) having the shape of circular segments for the parameters which have an influence upon the permissible load upon the dowel, and an outer scale (C) for the load, and a secondary data- setting device (6) provided with a point of origin (7) and a concrete strength scale (D) and a rotary pointer (8) for setting a chosen value on the scales. <IMAGE>

Description

SPECIFICATION Apparatus for the determination of permissible loads upon dowels The invention relates to an apparatus for the determination of permissible loads upon dowels used in building industry in dependence upon predetermined parameters of the anchoring ground in which the dowel is to be anchored, the dowels being provided for in a geometrical arrangement.

With every dowel specific technical data and characteristic values are associated, which relate to the determination of its bearing strength. For the determination of a permissible load for a specific dowel the following parameters must be taken into consideration: strength of a certain anchoring ground; distance of the dowel from a free edge of the structural member; axial pitch, i.e. the distance between the axes of the dowels; -Depth of anchoring of the dowel.

The parameters mentioned are generally summarized in the form of tables on data sheets. The application of these data sheets demands of the user a certain professional knowledge about the connection between and the interdependence of the various parameters.

From the West German OS 31 30 393 a device is known for the determination of the size of dowel which may be employed out of a series of types of dowel and of the load which is to be taken up by the dowel, in the form of a slide rule in which the series of values for the various parameters are arranged in parallel with one another. The data required may be read off through a window. For each series of values of the constituent parameters a scale is provided, having an individual sliding pointer.

The sliding pointers are formed by one-piece elements in the form of strips, which are provided at one longitudinal edge with the marking for setting as well as with a covering range.

As a consequence of new legal provisions relating to parameters, this slide rule becomes unsuitable. Practice has shown that when such an embodiment is used for the selection of a dowel size difficulties may frequently arise.

By the shifting of the markings for setting to the present values undesirable shiftings may take place, which may lead, unnoticed, to false readings.

The aim of the invention is to create an apparatus by means of which in a simple, clear, error-free way the permissible load upon a dowel may be determined in dependence upon predetermined parameters.

This aim is achieved by the features claimed in the appended claims.

The determination of the permissible loads for dowels is effected through the calculation of the respective influencing factors which satisfy different mathematical relationships, and in addition through the multiplicative superimposition of these factors.

The influence of the respective parameter for each size of anchor is represented in the form of a polar logarithm scale in the shape of a segment of a circle.

The lenghts of the arcs of the circular segments correspond with the permissible range of application in each case. Thus a certain angle is associated with each influence. Through the arbitrary addition of the angles associated with the respective influences the multiplicative superimposition of the factors of influence is performed. Hence the sum of the angles corresponds with taking into consideration of all the influences and at the same time with the angle by which the load is influenced in the further step. The scale of load is likewise represented by polar logarithmic setting on a circular arc. The logarithmic subtraction of the sum of the angles from the factors of influence, along the circular arc for the load yields the final load.

One embodiment of the invention is explained in greater detail below with reference to the accompanying diagrammatic drawing in which: Figure 1 3 front elevation of an appara- tus.

The apparatus represented in the drawing comprises a piece of cardboard coated with plastics and exhibits two data-setting devices 1 and 6, which are designed as two rotary discs of different diameter concentric with one another and connected at the centre, and a rotary pointer 8. With the rotary pointer 8 the determination of the permissible loads is commenced through the setting of the rotary pointer 8 at the point of origin 7. The primary data-setting device 1 has scales A, B, C, which are designed with logarithmic graduation.

Scale A is for the influence of a reduced distance from the edge upon the permissible load. It extends between ordinates 2 and 3, where the ordinate 2 determines the limiting distance, i.e., the distance from one edge of the concrete at which maximum bearing strength is still just reached, and ordinate 3 the shortest permissible distance from the edge.

Scale B serves for the influence of reduced axial pitch upon the permissible load. The ordinate 4 determines the limiting axial pitch, i.e., the pitch at which two or more anchors do not influence their bearing strength. For the further parameters which have an influence upon the load to be taken up by dowels, further scales, e.g. depth of anchoring, may be provided.

At the outer edge of the rotary disc 1 lies Scale C for the permissible loads. The secon dary data-setting device 6 serves as an auxiliary disc. It exhibits a Scale D of concrete strength and a point of origin 7.

Through the invention the determination of the loads is effected without laborious calculation and the method is thereby made considerably easier.

Claims

1. An apparatus for the determination of permissible loads upon dowels in dependence upon predetermined parameters of the anchoring ground in which the dowels are to be anchored in a geometrical arrangement, the apparatus comprising a primary data-setting device provided with at least two polar logarithmic scales having the shape of circular segments for the parameters which have an influence upon the permissible load upon the dowel, and an outer scale for the load, and a secondary data-setting device provided with a point of origin and a concrete strength scale and a rotary pointer for setting a chosen value on the scales.

2. An apparatus according to Claim 1, wherein the primary and secondary data-setting devices are in the form of two rotary discs concentric with one another and connected at the centre.

3. An apparatus according to Claim 1 or 2, wherein the rotary pointer is provided with a line running therethrough longitudinally.

4. An apparatus according to Claim 1 or 2, wherein the rotary pointer embraces both the rotary discs in the form of a transparent strap.

5. An apparatus according to Claim 1 constructed, arranged and adapted to operate substantially as herein described with reference to, and as shown in, the accompanying drawing.