轻钢结构檩条设计方案问题探讨.docx

1、轻钢结构檩条设计方案问题探讨轻钢结构檩条设计问题探讨摘要：PKPM-STS软件设计中檩条的强度及稳定计算提出一些应用思路。关键词：PKPM-STS； 屋面檩条； 墙面檩条 一、屋面檩条1.简支檩条计算通常选用C型檩条，开口朝向屋脊方向。如屋面为单层或双层彩钢板夹玻璃丝棉的维护材料，恒荷载通常取0.150.2KN/ 。其它材料跟据实际重量核算。活荷载取荷载规范规定的屋面活荷载与当地雪荷载的较大值。积灰荷载与施工荷载根据实际情况确定。如果屋面板采用自攻螺钉与檩条固定，保证屋面板与檩条可靠连接，能阻止檩条上翼缘侧向位移和扭转，此时只需计算檩条强度，但这种板型因温度变形能力和防水能力较差，现在较少采用

2、。目前采用较多的是暗扣式板型，这种连接方式在温度变化较大时屋面板能产生滑动，不宜将它假定为能阻止檩条上翼缘侧向位移和扭转，除了计算檩条强度，还需计算其稳定性。屋面檩条计算和拉条的设置有关。根据门规，当檩条跨度大于4m时，宜在檩条间跨中设置拉条；跨度大于6m时宜在檩条跨度三分点处各设一道拉条，在屋脊处还应设置斜拉条及撑杆。在恒载.活载及风压力作用下，檩条上翼缘受压，拉条应设置在檩条上翼缘1/3处。在风吸力作用下使檩条下翼缘受压，拉条不能保证檩条下翼缘的侧向位移和扭转，如果计算时要考虑拉条能约束檩条下翼缘，此时应在檩条下翼缘1/3处同样设置拉条，所以檩条设计最好用双层拉条。2.连续檩条计算通常选用

3、Z型檩条，开口朝向檐口方向。由于Z型檩条可用搭接形式，故可把这样的檩条假定成连续构件。(1) 采用Z 型搭接连续檩条比简支檩条内力分布均匀,刚度大,可节省用钢量。(2) 搭接连续檩条在支座处搭接区存在嵌套松弛现象,其刚度小于等截面连续单檩的刚度,因此在支座处有一定弯矩释放,在跨中弯矩有一定的增大。(3) 连续檩条整体稳定计算目前尚不完善,其整体稳定可利用屋面蒙皮作用和拉条支撑系统解决。(4) 连续檩条支座处的弯矩大于跨中弯矩,搭接区承载能力按两檩条的抗弯模量之和考虑是合理的,可以大大节省用钢量。(5) 连续檩条的搭接长度不宜小于跨长的10 % ,搭接长度按端跨和中间跨的弯矩分布情况分别考虑,以

4、搭接端弯矩不大于跨中弯矩为条件来确定搭接长度可使设计更为经济合理。(6) 用檩条兼作屋面纵向压杆,当单檩不能满足承载力要求,可用双檩条,此方法节省用钢量。(7) 连续檩条与屋面梁的连接应采用加檩托板螺栓连接方式以防檩条局部腹板压屈和整体倾覆。当檩条腹板高厚比较大时尚应加设厚垫片以改进其支座处的承载力。(8) 一般情况下,设计带隅撑的檩条时,隅撑对檩条的有利作用与不利影响可考虑相互抵消,忽略不计,以简化设计二、墙面檩条1. 简支墙梁计算通常选用C型檩条，开口朝向根据实际情况确定。一般墙梁开口朝上，但窗洞口下侧檩条可让檩条开口朝下布置以满足固定窗框的需求。墙梁设计与屋面檩条类似，同样要考虑墙板.拉

5、条的约束作用。不同的是墙板有自承重和非自承重两种，要根据具体情况具体分析。另外。墙梁设计时根据构造条件的不同要考虑双弯矩板的影响。根据冷弯薄壁型钢结构技术规范8.3.1条及条文说明，两侧挂墙板的墙梁和一侧挂墙板.另一侧没有可以阻止其扭转变形的拉杆墙梁，可不计双力矩的影响?(即可取B=0)，此时可仅进行墙梁的强度计算。对于风吸力作用下内翼缘的稳定性计算，与屋面檩条类似，墙板一般采用自攻螺钉与檩条固定，可认为墙板能阻止墙梁外翼缘侧向失稳。拉条设置在墙梁内侧比增大檩条截面更经济。对于自承重墙板，可仅在内侧设置拉条。对于非自承重墙板，宜在墙梁内外设双侧拉条，外侧拉条可以作为墙板在自重作用下墙梁的竖向支

6、撑点。在墙板顶部和窗户下的墙梁处应同时设置斜拉条和直撑杆，将拉力传至刚架柱或墙架柱，底部墙梁一般固定在墙垛或矮墙上，整体稳定有保证，故底部墙梁处可不设置斜拉条和直撑杆。三、拉条的设置拉条虽小，作用不小。实际上有檩条系的压型钢板轻型变形和扭转，减小檩条的计算长度，保证檩条的侧向稳定作用。拉条一般通过螺栓与檩条连接，拉条与屋面板的共同作用能有效地提高檩条的整体抗扭转度和减少外部荷载引起的扭转效应。虽然在檩条下翼缘附近有无拉条对檩条的抗弯承载力有很大影响，但当拉条强度满足后，拉条的刚度对抗弯和压弯承载力的影响可忽略。所以门规推荐拉条的最小直径取10mm，去除车丝对截面的削弱及锈蚀等因素外是可行的，但

7、应注意：每一个坡面上的檩条是一个大的串联系统，因此檩条的受力是不均匀的，恒活载作用下离屋脊处越近的拉条内力越大，而在风吸力作用下正好相反。在檩条的设计中应考虑多根檩条由拉条串联后的内力叠加。当房屋坡度方向较大应间隔一定数量的拉条设置一对斜拉条，以分段传递内力。因拉条只能受拉，但拉条作为檩条的侧向支撑点时，同时受拉和受压，因此在檐口和屋脊应布置斜拉条和撑杆，以形成几何不变体系。撑杆按压杆设计，不宜用圆钢。Light steel purlin design problem discussed in this paper Pick to: PKPM - STS software in the des

8、ign of purlin the strength and stability calculation of some applications. Keywords: PKPM - STS; Roofing purline; The metope of purlin A, roof purlin 1. The simply supported purlin is calculated Usually choose C purlin, ridge direction. Such as roofing for single or double colored powder glass cotto

9、n material to maintain, constant load usually take 0.15 0.2 KN / . Other materials according to the actual weight calculation. Live load in load code for the rules of roof live load and the larger value of the local snow load. Heavy load and construction load according to the actual situation. If ro

10、of board with self-tapping screws fixed and purlin, ensure roof panel and purlin connections, can prevent the purlin flange on the lateral displacement and torsion, just calculate purlin intensity at this time, but this kind of board type deformation due to temperature and waterproof ability is poor

11、er, less used now. Is currently using more dark buckle type plate type, the connection way in large temperature changes in the roof plate can produce sliding, unfavorable and it can prevent the purlin is assumed on the flange lateral displacement and torsion, in addition to the purlin strength calcu

12、lation, still need to calculate the stability. Roofing purline calculation and brace is set. According to the rules, when the purlin span more than 4 m, appropriate is set in the purlin across brace; A time span is more than 6 m in span purlin three locations in each set a brace, also should be set

13、at roof of batter brace and poles. At constant load. Under the action of live load and wind pressure, purlin flange compression and brace should be set on the purlin flange 1/3. Under the wind suction under the action of the purlin flange compression and brace does not guarantee purlin flange latera

14、l displacement and torsion under, if can brace should consider when calculating constraint purlin flange, should now under the purlin flange 1/3 place to stay with the same Settings, so the purlin design best double brace. 2. Continuous purlin calculation Usually choose Z type purlin, opening direct

15、ion toward the eaves. Since Z type purlin overlap forms are available, and it can be such a purlin assumed to continuous artifacts. (1) using lap than simply supported continuous purlin Z purlin internal force distribution is uniform, stiffness big, quantity of steel can be saved. (2) continuous pur

16、lin overlap overlap area exists in support nested flabby phenomenon, its stiffness is smaller than the cross-section stiffness of the single continuous purlin, therefore had a certain moment release in the bearing, the bending moment in the span have increased. (3) continuous purlin overall stabilit

17、y calculation is not yet perfect, the available roofing envelope on overall stability and brace support system. (4) continuous purlin bending moment is greater than the cross of bending moment of the bearing, bearing capacity according to the two overlapping area purlin bending modulus of the sum of

18、 the consideration is reasonable, can greatly save the steel quantity. (5) continuous purlin of the lap length should not be less than 10% span length, the lap length according to the bending moment distribution of end span and middle span were considered, with overlapping end bending moment is not

19、greater than midspan moment for the conditions to determine the lap length can make the design more economical and reasonable. (6) made roof purlin and longitudinal compressive bar, single purlin when can not meet the requirement of the bearing capacity of double purline are available, and this meth

20、od saves the quantity of steel. (7) continuous purlin beam connections should be used with the roof and purlin plate bolt connection in case of purlin local web buckling and overall overturning. When high purlin web thickness is larger fashion should be added a thicker gasket to improve its bearing

21、capacity. (8) in general, the design with a knee brace purlin, the beneficial effect of the knee brace to the purlin and adverse effects cancel each other out, may be considered negligible, to simplify the design Second, metope purlin 1. The simply supported beam wall is calculated Usually choose C

22、purlin, opening towards according to actual situation. Wall beam with opening up commonly, but humanly scaled mouth underside purline allows purlin opening downwards arranged to meet the needs of the fixed frame. Wall beam design and roof purlin is similar, also want to consider wallboard. Restricti

23、on in brace. Is different panels are self supporting and self supporting two kinds, according to particular case is particular analysis. In addition. When wall beam design according to the different tectonic conditions want to consider the impact of dual bending plate. According to technical specifi

24、cation for the cold bending thin-wall steel structure 8.3.1 and provisions that, on both sides of the hang hang wallboard wall beam and side wall. On the other side can not prevent the torsional deformation of rod wall beam, but excluding double moment of impact? (that is, the option B = 0), but onl

25、y the strength of the wall beam calculation at this time. For wind suction flange in the stability calculation, like roofing purline, wallboard generally USES self tapping screw and purlin fixed, can think outside wallboard can prevent wall beam flange lateral instability. Brace is set in the wall b

26、eam inside more economic than increasing the purlin section. For the bearing wallboard, can be set up only in the inside of the brace. For non self bearing wallboard, appropriate is set in and out of the wall beam dual lateral brace, the lateral brace can be used as wall panel in the weight of the w

27、all beam under the action of vertical support. On top of the wall panel and window of the wall beam should be set at the same time suspension and straight poles, would transmit the force to rigid frame column or wall frame column, the bottom of the wall beam fixed on the low wall or wall battlements

28、 commonly, the overall stability guaranteed, so the article didnt set at the bottom of the wall beam suspension and poles. Three, brace is set Brace is small, effect. Actually have purlin is pressed steel plate light deformation and torsion, reduce the purline length calculation, ensure the lateral

29、stability of purlin. Brace general through bolts and purlin connection, brace and roof plate can effectively improve the function of purlin of the torsion degree of whole and reduce the external load caused by the reverse effect. Although under the purlin flange near any brace has a great influence

30、on the flexural bearing capacity of purlin, but when meet brace intensity, stiffness of the brace effect on bending and bending bearing capacity can be ignored. So door gauge brace recommended minimum diameter 10 mm, remove the car silk weaken and corrosion factors of cross section is feasible, but

31、should pay attention: each of the side slope of purlin is a large series of system, so the purlin of the stress is not uniform, constant under the action of live load near the roof in the brace of the internal force, and under the wind suction is just the opposite. Should be considered in the design

32、 of the purline dogan purline series by brace after the internal force of the stack. When a certain number of housing gradient direction should be larger interval brace is set a pair of batter brace, to block transfer internal force. Due to stay only in tension, but as a purlin of the lateral brace support, at the same time in tension and compression, therefore in the eaves and roof should decorate a batter brace and poles, in order to form the geometric invariant system. Poles press rod design, unfavorable use round steel.