Precautions Foshan Steel Design
Time：[2016-6-15] Hits：4745
Followed by the State to vigorously promote Prefabricated construction today, Foshan steel construction and more subject to our attention. The following are some of Foshan Steel watch point plan for us to see.
A Frame
⑴ portal frame should first determine whether there is a crane, such as plant demand resettlement process requests crane, you should note the following: ① column foot should be planned into a rigid column base; ② column should be planned into uniform section column; ③ between support columns by longitudinal horizontal crane load control programs, rather than a simple construction planning, when there are no less than 5 t crane when, should use steel support. As no crane portal frame, press columns and other practices planning a wedge, not repeat them.
Room ⑵ column support resettlement
Between the columns support the roof support pillar should be placed in the same room, so that the formation of a stable system of longitudinal frame, frame means to facilitate and increase the longitudinal stiffness. Support should be placed between the top of the second column by column from time to time, when placed in the second inter-column list when the appropriate placement of a rigid column tied, and the rigid tie rod and the wind column longitudinal orientation together, make a direct transfer wind loads. The turning point in the frame (single-span roof of the house and column capitals and some centers and multi-span pole in the house and the roof) should be set rigid Tied houses along the entire length. When larger span gantry in place between support columns should be appropriate to increase the number of rigid tie rods that support the angle is about 45 °. When the construction of functional constraint that can not be disposed between the support column, should be placed longitudinal frame. And that they've done this to make a rigid connection between the end of the column beams, studs and then cancel the support of engineering, construction make placement more flexible, with good results.
⑶ roof and wall construction
Roof and wall construction approach is to increase the stiffness of the frame, the key way to avoid the outer frame plane instability. Purlins, wall beams generally composed of cold-formed thin-walled structures formed when the column spacing less than 6 m, when designing a brace, more than 6 m, located two brace. Here should be mentioned especially the oblique bars, school diagram process, we often see a lot of steel structure manufacturers or planners provided the oblique strut bar without setting conditions. Factor is the construction concept is not very clear, because after construction mechanics, disposed between the oblique strut bar, before the formation of a stable system. In the roof, walls planned resettlement should also be noted bracing, bracing is not a luxury it is to avoid perverting the compression flange provided. Studies have shown the first portal frame damage due to pressure caused by perverting the largest flange. Oblique inner flange beams converge at the column flange and frame is the emergence of perverting vital parts, there is provided bracing is very important. In addition, the "portal frame light house steel construction technical specification" CECS102: 2002 (hereinafter referred to as CECS102: 2002) rules: oblique beams in the bottom flange of the compression zone is also set bracing, a distance not greater than the corresponding compression wing edge width of 16 (235 / fy) 0.5 times. When you press a general portal frame, purlin distance of about 1500 mm, a spacer is provided a bracing purlins above conditions can be satisfied.
⑷ shear key
"CECS102: 2002" rules: column anchor should not be used to withstand the horizontal shear column foot portion, the horizontal shear force by friction between the floor and the concrete foundation (friction coefficient desirable 0.4) or set shear joints bear. This is the time of our accounting mast, usually displayed warning: "Let Shear pedestal demand!"
Analysis of these factors, the main door is made generally lighter weight structure, column friction soles of the feet and between the concrete foundation is small enough to resist lateral wind loads and seismic effects, it should set the shear key. Usually the shear key beam with angle iron or steel, the shear bearing capacity of the cross section of the weld should be accounted for, columns and soles of the feet of open space between the surface of the foundation secondary grouting. Specifically refer to "many high-rise residential construction steel structure node configuration detail" 01SG519 diagram on page 30 to gather a large sample 1,2 practices.
Means for positioning the column anchor ⑸
This is the planners generally ignores questions and anchors positioned in engineering practice inaccuracy or rigid frame construction of the device difficult project case everywhere, we also encountered such a situation, and later had to reinforcement. Analysis of factors, notably the non-convergence between the anchors, the overall stiffness of the poor in the process of pouring concrete in the anchor inevitably shift. In response to these factors, taken before pouring concrete column anchor embedded fixation process, the specific approach shown in Figure 1. Mounting bracket and bolt to form a small lattice columns, positioned so the anchor would facilitate accurate. ⑹ wind columns and frame the current convergence of wind portal frame column planning practice there are two mistakes: one is the wind column and frame made of the same wind columns and beams or hinged frame or just then, the wind column to both wind and participate vertical load effect and the effect of the horizontal level. The planners do not usually do such a frame of longitudinal wind checking. This is done omissions load, Project Planning is a taboo. I think you are a force bent structure that clearly should not complicate it by force. This approach is defective; Another approach is to wind column and frame on one axis, but do not think that wind column vertical load effects wind between columns and beams with a steel frame after welding joints connected. This practice is still a part of the vertical load transmitted to the column of wind, and the steel sheet is small lateral stiffness, vertical load at the onset of the effect is difficult to ensure that there is barely after the land transfer the wind load. These two approaches have disadvantages. Here we recommend the following practices:
Plant selection do legal grids, Pin top frame column axis wind shifted 500 ~ 600 mm, wind through the column flange adapter plate is connected to the frame beam stiffeners and plate convergence and vertical stiffener open a long hole, use an ordinary bolt adapter bolts approach shown in Figure 2. Figure 2 wind column and frame adapter bulk sample
Plan 2 steel structure
Select ⑴ steel building systems
Common constructions of steel construction system can be divided into pure and construction - support systems into two categories. Highly selective and construction material systems, the use of closely-related features. This requires the construction engineer should work closely with the architect, when the construction of functional constraint can not be set because the support system should be used pure structure. Pure system configuration because no anti-sway support, two vertical and horizontal directions to satisfaction, "the construction of earthquake planning standards" GB50011-2001 (hereinafter referred to as "anti-regulation") Section 5.5 of the elastic layer between the displacement angle less than or equal request 1/300, beam the column in vertical and horizontal directions should just pick; because of "anti-regulation" section 8. 3.4 rule: "when the column in two mutually perpendicular directions and beam rigid connection, should use box-section" Therefore, use of pure construction system, usually planning to box column column column inside the box but the process of applying rust and proper maintenance difficult, which is steel construction planning a major problem. They are also trying to choose the column method of pouring concrete in the plan, but because the box column separator disposed stiffening node area, pouring concrete very difficult; on the other hand, the country is still in the concrete pipe during the discussion, common planning software can not be accounted for accounting theory in the Journal of the different. Based on the above factors when planning constructions of pure steel, most still use non - concrete box section column. Own labor process selected word column strong and weak axes are rigid convergence algorithm, according to the "anti-regulation" section of Article 8.3.4 of the text is selected, "should", see also the mainland large selection of drawings and Planning Institute said planning in spreadsheets method, but calculation results are not satisfactory, the elastic layer between the weak axis direction displacement angle is still unable to meet the request, "anti-regulation" of Article 8. 3.4. Because the box column in the structure of some tough, so the idea when planning a multi-layer steel cylinder-shaped house built try to use planning to construct - support system. Construction engineers and construction division to coordinate as much as possible, through resettlement in demand resettlement support bearing floor, elevator, which do not open big hole in the wall to achieve the support of stealth. The results indicate the accounting practice engineering, construction support displacement control effect is very good, so that in addition to the choice of column-shaped material saving, anti-rust, the use of easy maintenance, easy convergence weak axis direction, it is a useful method.
⑵ node Planning
Steel structure node planning is the key to planning steel structure. Hinged nodes simple, clear contact mechanics, where not too much to say, just focus on what connected node planning. Moment resistant convergence plan, "anti-regulation" 8 3.4 Recommended use Standard Figure 8. 3.4 - The node 1 in the form, in engineering practice are mostly chosen is such a node. This node has two accounts in accordance with: accurate programming and general programming. The difference between the two is that the former Reflections bending and shear webs, the latter only ponder web shear. Accurate planning law planning in practice, difficult bending webs satisfied request must be thickened to a large extent the web. The approach is very thick web of economic, so most use common project planning method, this accounting model Mechanics clear, simple accounting, but must pay attention to planning to take measures to strengthen the earthquake, such as the use of the plastic hinge relocation enhanced convergence or end of the beam away from the beam ends not far from the upper and lower flange beams weaken dog bone convergence. This is because, in the end without any reinforcing beam flange case, only ponder web convergence shear bolts bear, bear moment by the flange weld, then weld flange flexural capacity of only about 80% capacity BEAMS (that is, only beams with the section modulus of the beam flange section modulus of about 80%), then press the "steel construction planning standards" on page 3. 2.2, thinking construction site conditions weld strength reduction factor 0 is multiplied by the value of planning. 9, then the flexural capacity of the beam flexural capacity of Cohesion only 70% to 75%. This strong convergence node ratio is even lower 30% to 25%, in violation of the "earthquake not fall," the basic principles of earthquake "strong nodes, weak bars." Based on the above factors, it should be used "many high-rise residential construction steel structure node configuration detail" earthquake shown on page 19, 20 01SG519 portfolio strengthened approach.
Else
In our "anti-regulation" and "the Rules" the rules were not steel structure seismic level, just 12 minutes and 12 layers or less standard and two or more layers. I thought it was relative to our vast big difference around the fortification is characterized by inappropriate. Old "the Rules" in the multi-set size of a house built high-rise steel expansion joints no rules, only single industrial plant made some rules. These two points are the conceptual big question, "the Rules" does not emphasize these two points is appropriate.
