Often hear the saying: "a certain software than a certain software province the amount of steel, of course, who say such things are generally not of our professional people, at most, is a little knowledge, however, as a true professional design staff know about the specific component design process how much? There are a large number of software users in the design of steel structures industry, therefore, as preparation software in the design field, it is necessary to do some things: different software on the same conditions as the same below a engineering calculations to see the results in the end there is much of a difference.
The selected areas of light steel structure, because this is the use of the most extensive and the most sensitive to the amount of steel structures, I just did a software, so often heard the most about light the issue of the amount of steel in steel.
Popular software are the industry today, they the: 3D3S, STS, PS2000 also Maggie_GJ.
I. Project Introduction
Selected works as follows:
Two spans 27m, hipped slope of 1/20, cornices elevation 7.5m column spacing 9m material Q235. Diagram is shown below, as indicated by a clear cross-section beams and columns specifications (beam marked only the left cross, right symmetrically), member ID inside the circle, the segment size of the beam member also made a mark.
Load:
Roof dead load: 0.2 KN/m2
Roof live load: 0.3 KN/m2
Basic snow load: 0.45 KN/m2
Basic wind pressure: 0.45 KN/m2
Not consider earthquakes.
Second, analysis of results
In order to get accurate conclusions, we do not use the software to optimize the function of the components, but simply checking the member section given here give only the number calculated by the software components control stress.
Consider a factor of 0.6 (knee bracing effect), control the stress of the stability of the stress in the plane, in brackets the value of the stability of the stress in the plane.
In column (8 members), stress control plane stability stress For the purposes of this case, because of the live load is evenly distributed, and the structure symmetry, the column axis force, so the cross-section according to the calculation is relatively small, but the actual situation Due consideration should be given to the uneven distribution of the load, where the calculation result is not considered, the brackets for the stability of the stress in the plane value.
For oblique beam (2-7 member), the the gantry frame light house steel structure technical regulations (CECS 102: 2002) provides that calculation of its intensity in the plane before computing its stable plane bending member, but 3D3S and STS gives stability plane stress, but also control stress. "Portal frame light housing steel structure technical regulations" (CECS 102: 98), he says that the calculation of the length of the vertical support point spacing oblique beam plane, this was removed in subsequent procedures . If the plane stable calculated as a bending member, the inclined beams should be a bent components, and the axial pressure along the rod axis direction or the horizontal direction to consider it? There is stability factor is calculated according to this calculation length is the point? So like the column as a bending member as to calculate the plane's stability is a bit far-fetched. Calculated stability outside the plane is actually calculated the overall stability of the flexural members, but also to take into account the axial force. But still beam characteristics. Maggie not calculated the stable stress within the so-called plane.
Third, extraneous words
Control stress table view from above, basically very close, just PS2000 slightly higher, this may be my version earlier. Therefore, we can say that the key to the so-called savings in the amount of steel is not software, but the use of the software, the software is only a tool, like a calculator. That kind of hope that the little people do not know the component design process can be easily completed ideal structural design software, even if there is, it is also a potential bomb. It generated construction drawings, you can fool the layman's owners also make professional knowledge you Dousheng unlimited expansion of self-confidence, steel structure design and feel much better than this.
Real structural engineers have the skills of mechanics, approximate the stress state in a variety of boundary conditions have a certain feeling for the structure under a load, especially flat-structure system for complex spatial structure system With the help of structural analysis software to understand the stress condition. Second, we need to have the theoretical basis of the component design axial compression member of Compression Members need to consider in terms of steel structures, should be clearly understood. Also need to master the common node connection and the calculation method, some experience issues involved here. Also need to know, but outside of the design fabrication and installation knowledge, because a lot of these issues need to be considered during the design phase. Of course, the most important thing as the sense of responsibility of the structural engineer.
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