GB2406180A - Structural design apparatus - Google Patents

Abstract

A computer-based structural design system for a building includes a 3-dimensional structural design module for generating a computer model of the building. The model includes data defining architectural features of the building, the data comprising dimensions of the building and of principal load-bearing structural members of the building. A user interface comprises a display for displaying an image of the building model 300. A surface selector allows a user to select a surface of the building displayed, the surface being a continuous roof or wall having a boundary definable from the model data 302. A structural member design module is configured to define secondary structural members 304 of the selected surface on the basis of data in the model. The secondary structural members may be purlins or side rails. A method of the invention also comprises determining design features of principal load bearing members and secondary member based upon their interrelation and user defined design criteria for the secondary members.

Description

1 2406180 Structural Design Apparatus and Method Therefor This invention

relates to a structural design apparatus and method therefor incorporating a computer aided design facility, and in particular but not exclusively, an apparatus and method for use in the design of steel framed structures.

A known structural design apparatus and method is the subject of European Patent Specification 1 150 223. The apparatus and method described provides for the selection of, for example, roof purlins or side rails and optimisation thereof having regard to uses specified building parameters. The apparatus and method takes into account wind load values which may be imposed on the building with reference to a predetermined wind load algorithm. The apparatus provides for alternative structural member design options calculated on the basis of the user-selected alternative parameter and the wind load values. The apparatus and method of this system is limited to performing a structural design in relation to structures of predetermined shape and size selected from a library of possibilities. The disadvantage with the system is that it only provides structural design in relation to a limited range of building shapes and sizes.

A further disadvantage of this known system, particularly in relation to portal frame buildings is that it is only concerned with the design of the cold rolled members and does not include any interface with the design calculations required for the associated hot-rolled structural members.

It is an aim of the present invention to provide a design apparatus and method which alleviates this problem.

According to the present invention, there is provided a design method comprising creating a three dimensional structural model including shape and size data for a desired building structure, defining surfaces of said three dimensional structural model, displaying a representation identifying said surfaces, selecting one of said surfaces, collecting design information from the three dimensional structural model relevant to said selected surface, running a program for determining the c c c: c. c c. c. a structural members required for said surface and updating said three dimensional model to incorporate said determined structural members.

Surface is intended to include any continuous wall or roof component of the building having a definable boundary. For example, a simple structure having a rectangular floor plan and duo pitch roof is made up of surface shapes consisting of two sloping roof surfaces and four wall surfaces. Introduction of a feature, such as a door or window, into a wall or roof has the effect of dividing the wall or roof into a plurality of smaller continuous surface shapes which the program can recognise for determining the required structural members. In other words, architectural features of the building define the boundaries of the surfaces making up the structure.

The step of defining the surfaces of the three dimensional structural model comprises identifying a surface shape bounded by architectural features of the building structure, wherein the surface shape corresponds to one of a library of shapes.

In a preferred embodiment, the method further includes the step of identifying a macro corresponding to the surface shape, the macro controlling operation of the program for determining the structural members.

More preferably, the method further includes the step of identifying surface shapes from the three dimensional structural model that correspond to shapes contained in the library of shapes. Where required the method may further include the step of dividing a surface into shapes that correspond to shapes in the library.

This ensures that the surface selected has a shape that corresponds to one of the library of shapes, and for which there is a macro.

Embodiments of the present invention represent an integrated design system for the entire structure which allows the designer to vary the parameters of one component of the structure while seeing the inter- related effects of this on other components. In the prior art the designer has to use a three dimensional model to generate the design information and, as a separate step, design the purling and input them into the three dimensional model. The problem with this is that the purlins may 3:e:e ae.e :e be.

have an impact on other parts of the building structure and may themselves be affected by the design of other parts, e.g. the hot rolled members (columns and rafters) of the portal frames. When this occurs, the designer is required to redesign the purlins and re-input them into the three dimensional model as an independent exercise. The present system allows the designer to modify the purlins or side rails to take account of the design (or changes thereto) of other parts of the structure, e.g. the portal frames.

In embodiments of the present invention, the three-dimensional model may also include a detailing module. This module provides for the determination of the ancillary components required for construction, for example, corner brackets, cleats and bolts. I The program for determining the structural members of the selected surface may include a detailing routine which provides the required information for the three dimensional model to operate the detailing module. In consequence, the system is operative for transmitting a component list to a remotely located manufacturing or warehouse facility.

According to the present invention, there is also provided an apparatus for creating a three dimensional structural model for a desired building structure comprising: a user input for receiving user-specified data relating to shape and size of said structure; a display for displaying a representation of said structure including surfaces; a store for storing representations of a plurality of surface shapes; a selector providing for selection by the user of one of said surfaces; a processing apparatus for defining said surfaces, each surface having a shape corresponding to one of said stored surface shape representations, collecting design information from the three dimensional structural model relevant to said selected surface, for determining the structural members required for said surface, and for updating said three dimensional model to incorporate said determined structural members.

1 '' . . 4 ' . : ., According to the present invention, there is further provided a method for determining interrelated structural member design parameters for a building structure comprising principal load bearing members such as hot rolled portal frame columns and rafters, and secondary load bearing members such as roof purlins and side rails, the method comprising: i) inputting building envelope data; I ii) displaying a representation of said building; iii) determining an outline design for said secondary members according to user specified design criteria such as wind or snow load criteria; iv) determining design features of said principal load bearing members I having regard to the determined outline design of said secondary members; v) modifying said outline design for at least some of said secondary members so as to optimise a design for said principal members; vi) evaluating said modified outline design of said secondary members and determining whether said user specified design criteria are still met; vii) adjusting said secondary member design in dependence upon the determination of step vi); and viii) repeating steps iv) to vii) until said user specified design criteria are I met.

According to the present invention, there is further provided a data carrier having a program, which when run on a computer, configures the computer to perform the method defined hereinabove. A data carrier may be a CD Rom or data signals transmitted via an Internet link.

An embodiment of the invention will now be described by of an example with reference to the following drawings, in which: Figure 1 is a wire- frame illustration of a simple portal frame building structure; s:e Pe-;-.

Figure 2 is a wire-frame illustration of a building structure made up of a multiple of portal frame structures; Figure 3 is a frontal elevation of a complex building structure made up of multiple portal frame structures; Figure 4 is schematic representation of a structural design system according to the present invention; I Figure 5 is a is flow chart illustrating the operational steps in a portal frame design procedure employing the system of Figure 4; Figure 6 is a wire-frame outline of a portal-frame building structure showing a selected slope surface; I Figure 7 is a wire-frame outline of the portal frame building structure of Figure 6 showing a purlin design arrangement for the selected slope surface; and Figure 8 is a side elevation of a wall of a building structure.

Referring to Figure 1, a portal frame building structure 10 is made up of principal and secondary structural members. Typically the structural members are steel members manufactured using either hot or cold rolling methods. The principal members include columns 12, rafters 14. The secondary members include side rails and roof purlins 16. The columns 12 and rafters 14 together make up a series of parallel portal frames 18, which represent the principal load-bearing members of the I building structure 10. These portal frame members are typically manufactured from hot-rolled steel. The purlins 16 are typically manufactured from coldrolled steel. In addition the vertical walls may include horizontal side rails (not shown) running between the columns, and these would also be of cold-rolled steel.

Referring to Figure 2, a more complicated portal frame building 20 is shown.

The building 20 is made up of a row of adjoining portal frame structures 22a - 22d.

Each of the structures 22a- 22d has a tripped roof comprising two trapezoidal slope surfaces 24a- 24d, 25a- 25d, and two triangular slope surfaces 26a- 26d, 27a - 27d. l Moreover the heights and breadths of each of the portal frame structures 22a - 22d are different.

The wire-frame illustrations shown in Figures 1 and 2 have been generated by the three-dimensional design model StruCad _. In constructing the model, the 6! . . . !. j designer has input the principal dimensions of the architectural features of the buildings, and defined the number and spacing of the portal frames 18. StruCad _ iS a design modelling package which provides information regarding the structural members of a building. StruAnalysis_ is a design module for the hot-rolled structural members which, in accordance with embodiments of the invention, is suitable for integration with StruCad_. However, the design of the cold-rolled l members (purling and side rails) is left to the to the designer. MetSpec_ is a purlin and side rail design module which is integrated with StruCad_ and StruAnalysis_ in accordance with embodiments of the invention as will be described in more detail later. An exemplary system is known as MetPORT_. l Established methods exist for designing the cold-rolled structural members for portal frame buildings such as that shown in Figure 1. Depending on the degree of sophistication of the method, various simplifications or assumptions are made regarding the structure and the loads that they are designed to support. A feature in common with these methods is that each portal frame structure is designed as a unit, in isolation. To take account of adjoining structures, the designer must make estimates of its influence, or apply predefined rules. This is a time consuming operation. Also, to ensure design safety, the imprecise nature of these methods means that the portal frame structures tend to be over-designed, so that more, larger steel l members are used than are necessary. A further problem with these known methods arises because the design of the building structure as a whole Is not integrated, but, in the case of the building of figure 2, exists as four separate portal frame designs. For example, the four portal frame designs may include four different arrangements of roof purling, whereas a common roof purlin design for all four of the portal frame structures 22a - 22d would provide a simpler or more cost effective design.

Figure 3 shows a frontal elevation of a complex building structure 30 made up of a series of portal frame structures 32a- 32d. This shows more detail of the l influence of adjoining building structures on the design loads. In this case, the building includes a roof gulley 34 between a parapet 35 and a mono-pitch roof slope 36. There is another gulley between a sidewall 37 of a high-bay structure 32b, and a roof slope 38 of a duo-pitch structure 32c. In these pulleys the roofs must be capable of supporting a build up of snow. In addition, the wind loadings on the roof slopes, c: ce 7 e, side walls and end walls will be different for each of the structures 32a - 32d. It will be appreciated that the simplified design methods referred to above are unable to account for these differences without over-design or lengthy time-consuming calculations.

Referring to Figure 4, the MetPORTrM structural member design system 100 is installed on a computer (not shown), such as a personal computer or other similar device, having a memory, processor, visual display and user input devices, including a mouse and a keyboard. The system 100 includes program modules installed in the computer memory for execution by the processor in response to user input instructions.

The modules include a three-dimensional portal frame model 102 StruCad _, A model generated in StruCad _ by a user input produces a geometry 104 which is displayed to the user, for example as a wire-frame illustration. A surface selector 106 allows the user operating the mouse to move a cursor so as to select a wall or roof surface. An interface 108 is provided for allowing the user to initiate operation of structural member design module 110 of the cold rolled structural members for a selected surface using a software package such as MetSPEC8 _.

The MetSPEC8 _ structural member design module 110 includes a purlin design module 111 and a side rail design module 112. The system also includes a slope shape macro module 114 containing a library of recognised slope shapes and associated macros. The macros contain instructions for controlling the purlin design module 111 of MetSPEC8 _ to design the purlins for a selected roof slope surface.

The system also includes a face shape macro module 116 containing a library of recognised face shapes and associated macros. The face shape macros 116 contain instructions for controlling the side rail design module 112 of MetSPEC8 rM to design the side rails for the selected wall face surface. Other data required for this calculation is provided from the three-dimensional model 102 and geometry module 104.

The system further includes an automatic detailing module 118. This module determines details relating to the purlins or side rails designed using the structural 8 e member design software 110. The details include information about the ancillary components required for construction, for example, sleeves, tie wires, struts, cleats and bolts. This information is passed to the three-dimensional model 102 for inclusion in a full details listing of the building structure. The full details listing may be provided to a manufacturing facility for supply of all the structural members required for the building's construction.

Referring to Figure 5, the designer starts the procedure for operation of the system of Figure 4 at step 200. At step 201 the designer creates a three-dimensional model of the building using StruCad _, SO that the geometry of the building structure is displayed. At step 202 the designer decides, by an appropriate selection using the interface 108, to carry out either a purlin design or a side rail design. The interface 108 includes a Metport'M Options button which is displayed for the designer to allow him to make the selection. For a purlin design, at step 204, the designer then selects a roof slope surface by placing the cursor on a point on the appropriate roof slope surface of the building structure displayed. This activates the slope shape macro 114 which controls the operation of the MetSPEC8 _ purlin design for the shape of the selected surface. Data relating to the geometry of the surface is imported from the three-dimensional model 102 at step 206 (as shown by the broken lines in Figure 5), and at step 208 the purlin design is carried out.

The MetSPEC8 _ purlin design allows the designer to input certain additional data not determinable from the three-dimensional model, or to make choices where required at this stage. The additional data includes, for example, the wind loadings on the building, or other information from which MetSPEC8 _ iS able to determine wind loadings.

Once the purlin design stage has been completed, the automatic detailing module 118 uses the purlin data, together with geometry data from the three dimensional model to generate the detailing data for the selected surface at step 210.

This data together with the purlin geometry data generated by MetSPEC8 _ iS passed back so as to update the three-dmensional model at step 201.

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9 . . A similar process is used to design the side rails, when this option is selected by the designer using the Metport Options button at step 202. The process is shown in steps 214 to 220. At step 232 the designer is presented with the opportunity to copy any of the design data for other slopes or faces. This facility is used where the designer knows that the same geometry and load conditions apply to more than one surface, and avoids the need for unnecessary repetition of design calculations.

At step 234, the system allows the designer to design the structural members of any additional surfaces by returning to step 204 or step 214 as appropriate. These may include surfaces for which no design has yet been performed, or for which the designer wishes to make alterations.

If the designer requires no further cold rolled structural member designs for any surfaces, the procedure advances to step 236 where the hot-rolled structural members of the portal frames are designed using the portal frame analysis program StruAnalysis _, This is the portal design optimiser module 120 of Figure 4, which allows the designer to vary, having regard to his design expertise and discretion to optimise certain parameters so as to meet design criteria or to optimise the portal frame design. The parameters that can be varied include the design (e.g. the size or spacing) of some or all of the cold-rolled members (purling or side rails). For example, with a view to reducing the rafter size the designer may adjust the purlin spacing.

When an alteration has been made, the designer needs to recalculate the purlin or side rail design to check that these satisfy the design requirements for these members. Thus at step 238 a determination is made as to whether there has been an alteration, and the process returns to MetSPEC8 _ at step 208 or step 218, as appropriate, to perform the recalculation. Because the system already has all the information it needs (i.e. geometry, wind loads, snow loads etc.) from the three- dimensional model and the initial purlin or side rail design, it can immediately perform the required recalculation.

The recalculated purlin or side rail design is fed back to the three dimensional model at step 201, by way of the automatic detailing routine at step 210 or 220. Thus ''. 2. .... . ' It,.

the procedure goes through a loop which can be repeated as many times as required until the designer is satisfied.

Once all the hot and cold-rolled structural members have been designed at step 238 it is determined that no further changes have been made that require recalculations, the procedure ends at step 240. However, all the data is contained in the computer system memory, and so it is straightforward for the designer to return to the procedure and undertake a re-design or make adjustments.

The structural design system and method shown in Figures 4 and 5 makes use of the identification of the shape of a surface. Figures 6 and 7 show a portal frame structure 300 having a tripped roof. The roof has a slope surface 302 which has a trapezoidal shape. When the designer wishes to design the roof purlins for this slope surface 302, he places the cursor on the slope surface 302 of the displayed structure and selects it (e.g. by clicking an appropriate mouse button). The system highlights the slope surface 302 on the screen, as shown in Figure 6. The system does this because it identifies the shape of the surface as a trapezium, which is one of the shapes contained in the library of shapes for which there is a purlin design macro in the slope shape macros module 114.

After the purlin design has been completed, the three-dimensional StruCad _ model is updated to include the purling, and so these are displayed as shown in Figure 7 by reference numeral 304.

When a surface includes an architectural feature, the system can only perform a structural member design if it can recognise the shape of the surface as corresponding to one for which there is a macro. For example, if a door is placed in a wall, the shape of the wall surface surrounding the door may not be one for which there is a corresponding macro. In such circumstances, the system divides the wall surface into smaller shapes for which there are corresponding macros. This can be seen in Figure 8, where a wall 310 containing a door 312 has been divided into a rectangular shape area 314 above the door, and two further rectangular shaped areas 316 and 318 either side of the door. In this case the system will perform a side rail design for each of the rectangular areas 314, 316, 318. Note, however, that the system st::e :e:e at:.

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allows the designer the freedom to modify the design of the side rails in any of these areas, and by doing so can ensure that a common size of side rail is used for all three areas if he so desires. /=

Claims (16)

1. A computer-based structural design system for a building, comprising: (i) a 3-dimensional structural design module for generating a computer mode] of the building, including data defining architectural features of the building, the data comprising dimensions of the building and of principal load-bearing structural members of the building; (ii) a user interface comprising a display for displaying an image of the building model; (iii) a surface selector for allowing a user to select a surface of the building displayed, wherein the surface is a continuous roof or wall having a boundary definable from the model data, and (iv) a structural member design module configured to define secondary structural members of the selected surface on the basis of data in the model.

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2. The structural design system of claim 1 wherein the structural member design ë .. module comprises a purlin design module for designing purlins on a selected roof surface, and a side rail design module for designing side rails on a selected wall ë surface. :.

3. The structural design system of claim 1 or claim 2, further comprising a .. library of surface shapes and associated macros containing instructions for controlling the structural member design module to design the secondary structural members.

4. The structural design system of claim 2, wherein the surface selector is operable for selecting a surface having a shape that corresponds to a shape in the library.

5. The structural design system of claim 4 wherein the surface selector is operable for dividing a surface that does not correspond to a shape in the library, into a plurality of smaller continuous surface shapes that do correspond to shapes in the library.

6. The structural design system of any preceding claim wherein the surface selector is operable for highlighting the selected surface on the display.

7. The structural design system of any preceding claim, further comprising a detailing module for determination of ancillary components required for construction of the building.

8. The structural design system of any preceding claim wherein data relating to] the secondary structural members and any ancillary components is added to the model.

9. The structural design system of claim 8, further including a structural analysis module for designing the principal load-bearing members of the building on the basis of data in the model. :e

10. The structural member design system of claim 9 wherein the structural . analysis module includes an optimiser module for allowing the user make an . . alteration to data in the model so as to optimise design of the principal load-bearing .

members. .

11. The structural member design system of any preceding claim wherein, responsive to the alteration, the structural member design module is configured to; recalculate the secondary structural member designs to check that these satisfy design requirements.

12. The structural design system of any preceding claim, further comprising means for defining design loadings applied to surfaces of the building.

13. A method for determining interrelated structural member design parameters for a building structure comprising principal load bearing members such as hot rolled portal frame columns and rafters, and secondary load bearing members such as roof I purlins and side rails, the method comprising: i) inputting building envelope data; ii) displaying a representation of said building; i] iii) determining an outline design for said secondary members according to user specified design criteria such as wind or snow load criteria; iv) determining design features of said principal load bearing members having regard to the determined outline design of said secondary members; v) modifying said outline design for at least some of said secondary members so as to optimise a design for said principal members; vi) evaluating said modified outline design of said secondary members] and determining whether said user specified design criteria are still met; vii) adjusting said secondary member design in dependence upon the determination of step vi); and viii) repeating steps iv) to vii) until said user specified design criteria are met. ...

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14. A data carrier having a program, which when run on a computer, configures I the computer to perform the method of claim 13. !

15. A system configured to perform the method of claim 13, wherein at least one of the steps is performed by a computer with data being passed to/from the computer over the internet. 1

16. A structural design system substantially as hereinbefore described with reference to the accompanying drawings.