輕鋼結(jié)構(gòu)檁條設(shè)計方案問題探討

1、輕鋼結(jié)構(gòu)檁條設(shè)計問題探討摘 要：PKPM-STS軟件設(shè)計中檁條的強度及穩(wěn)定計算提出一些應(yīng)用 思路。關(guān)鍵詞：PKPM-STS ；屋面檁條； 墻面檁條一、屋面檁條1簡支檁條計算通常選用C型檁條，開口朝向屋脊方向。如屋面為單層或雙層彩鋼板夾玻璃絲棉的維護材料， 恒荷載通常 取0.150.2KN/ m2。其它材料跟據(jù)實際重量核算?；詈奢d取荷載規(guī)范 規(guī)定的屋面活荷載與當?shù)匮┖奢d的較大值。 積灰荷載與施工荷載根據(jù) 實際情況確定。如果屋面板采用自攻螺釘與檁條固定，保證屋面板與檁條可靠連 接，能阻止檁條上翼緣側(cè)向位移和扭轉(zhuǎn)，此時只需計算檁條強度，但 這種板型因溫度變形能力和防水能力較差，現(xiàn)在較少采用。目前采用

2、較多的是暗扣式板型，這種連接方式在溫度變化較大時屋面板能產(chǎn)生 滑動，不宜將它假定為能阻止檁條上翼緣側(cè)向位移和扭轉(zhuǎn)，除了計算檁條強度，還需計算其穩(wěn)定性。屋面檁條計算和拉條的設(shè)置有關(guān)。根據(jù)門規(guī)，當檁條跨度大于 4m時，宜在檁條間跨中設(shè)置拉條；跨度大于6m時宜在檁條跨度三分點處各設(shè)一道拉條，在屋脊處還應(yīng)設(shè)置斜拉條及撐桿。在恒載活載及風壓力作用下，檁條上翼緣受壓，拉條應(yīng)設(shè)置在檁條上翼緣1/3處。在風吸力作用下使檁條下翼緣受壓，拉條不能保證檁條下翼緣的 側(cè)向位移和扭轉(zhuǎn)，如果計算時要考慮拉條能約束檁條下翼緣，此時應(yīng)在檁條下翼緣1/3處同樣設(shè)置拉條，所以檁條設(shè)計最好用雙層拉條。2連續(xù)檁條計算通常選用Z型檁條

3、，開口朝向檐口方向。由于 Z型檁條可用搭 接形式，故可把這樣的檁條假定成連續(xù)構(gòu)件。(1) 采用Z型搭接連續(xù)檁條比簡支檁條內(nèi)力分布均勻，剛度大，可 節(jié)省用鋼量。(2) 搭接連續(xù)檁條在支座處搭接區(qū)存在嵌套松弛現(xiàn)象 ，其剛度小 于等截面連續(xù)單檁的剛度，因此在支座處有一定彎矩釋放，在跨中彎矩 有一定的增大。(3) 連續(xù)檁條整體穩(wěn)定計算目前尚不完善 ，其整體穩(wěn)定可利用屋 面蒙皮作用和拉條支撐系統(tǒng)解決。(4) 連續(xù)檁條支座處的彎矩大于跨中彎矩 ，搭接區(qū)承載能力按兩 檁條的抗彎模量之和考慮是合理的，可以大大節(jié)省用鋼量。(5) 連續(xù)檁條的搭接長度不宜小于跨長的10 % ,搭接長度按端跨 和中間跨的彎矩分布情況

4、分別考慮，以搭接端彎矩不大于跨中彎矩為 條件來確定搭接長度可使設(shè)計更為經(jīng)濟合理。(6) 用檁條兼作屋面縱向壓桿，當單檁不能滿足承載力要求，可用 雙檁條，此方法節(jié)省用鋼量。(7) 連續(xù)檁條與屋面梁的連接應(yīng)采用加檁托板螺栓連接方式以 防檁條局部腹板壓屈和整體傾覆。當檁條腹板高厚比較大時尚應(yīng)加設(shè)厚墊片以改進其支座處的承載力(8) 般情況下，設(shè)計帶隅撐的檁條時，隅撐對檁條的有利作用與 不利影響可考慮相互抵消，忽略不計，以簡化設(shè)計二、墻面檁條1. 簡支墻梁計算通常選用C型檁條，開口朝向根據(jù)實際情況確定。一般墻梁開 口朝上，但窗洞口下側(cè)檁條可讓檁條開口朝下布置以滿足固定窗框的 需求。墻梁設(shè)計與屋面檁條類似

5、，同樣要考慮墻板 拉條的約束作用。 不同的是墻板有自承重和非自承重兩種，要根據(jù)具體情況具體分析。 另外。墻梁設(shè)計時根據(jù)構(gòu)造條件的不同要考慮雙彎矩板的影響。根據(jù)冷彎薄壁型鋼結(jié)構(gòu)技術(shù)規(guī)范條及條文說明，兩側(cè)掛墻板的墻梁和一側(cè)掛墻板.另一側(cè)沒有可以阻止其扭轉(zhuǎn)變形的拉桿墻 梁，可不計雙力矩的影響？(即可取B=0)，此時可僅進行墻梁的強度計 算。對于風吸力作用下內(nèi)翼緣的穩(wěn)定性計算，與屋面檁條類似，墻板一般采用自攻螺釘與檁條固定，可認為墻板能阻止墻梁外翼緣側(cè)向失 穩(wěn)。拉條設(shè)置在墻梁內(nèi)側(cè)比增大檁條截面更經(jīng)濟。對于自承重墻板， 可僅在內(nèi)側(cè)設(shè)置拉條。對于非自承重墻板，宜在墻梁內(nèi)外設(shè)雙側(cè)拉條， 外側(cè)拉條可以作為墻板

6、在自重作用下墻梁的豎向支撐點。在墻板頂部和窗戶下的墻梁處應(yīng)同時設(shè)置斜拉條和直撐桿， 將拉力傳至剛架柱或 墻架柱，底部墻梁一般固定在墻垛或矮墻上，整體穩(wěn)定有保證，故底部墻梁處可不設(shè)置斜拉條和直撐桿。三、拉條的設(shè)置拉條雖小，作用不小。實際上有檁條系的壓型鋼板輕型變形和扭 轉(zhuǎn)，減小檁條的計算長度，保證檁條的側(cè)向穩(wěn)定作用。拉條一般通過 螺栓與檁條連接，拉條與屋面板的共同作用能有效地提高檁條的整體 抗扭轉(zhuǎn)度和減少外部荷載引起的扭轉(zhuǎn)效應(yīng)。雖然在檁條下翼緣附近有無拉條對檁條的抗彎承載力有很大影響，但當拉條強度滿足后，拉條的剛度對抗彎和壓彎承載力的影響可忽略。所以門規(guī)推薦拉條的最小直徑取10mm，去除車絲對截

7、面的削弱及銹蝕等因素外是可行的，但 應(yīng)注意：每一個坡面上的檁條是一個大的串聯(lián)系統(tǒng)，因此檁條的受力是不均勻的，恒活載作用下離屋脊處越近的拉條內(nèi)力越大，而在風吸力作用下正好相反。在檁條的設(shè)計中應(yīng)考慮多根檁條由拉條串聯(lián)后的 內(nèi)力疊加。當房屋坡度方向較大應(yīng)間隔一定數(shù)量的拉條設(shè)置一對斜拉 條，以分段傳遞內(nèi)力。因拉條只能受拉，但拉條作為檁條的側(cè)向支撐 點時，同時受拉和受壓，因此在檐口和屋脊應(yīng)布置斜拉條和撐桿，以 形成幾何不變體系。撐桿按壓桿設(shè)計，不宜用圓鋼。Light steel purli n desig n problem discussed in this paperPick to: PKPM -

8、STS software in the desig n of purli n the stre ngth and stability calculati on of some applicati ons.Keywords: PKPM - STS; Roofi ng purli ne; The metope of purli nA, roof purli n1. The simply supported purli n is calculatedUsually choose C purli n, ridge directi on.Such as roofi ng for sin gle or d

9、ouble colored powder glass cott on material to maintain, constant load usually take 0.15 0.2 KN /. Othermaterials 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 con structi on load accord

10、ing to the actual situati on. If roof board with self-tapp ing screws fixed and purli n, en sure roof panel and purlin connections, can prevent the purlin flange on the lateral displaceme nt and tors ion, just calculate purli n inten sity at this time, but this kind of board type deformation due to

11、temperature and waterproof ability is poorer, less used no w. Is curre ntly using more dark buckle type plate type, the conn ecti on way in large temperature cha nges in the roof plate can produce sliding, unfavorable and it can prevent the purlin is assumed on the flange lateral displaceme nt and t

12、ors ion, in additi on to the purli n stre ngth calculatio n, still n eed to calculate the stability.Roofi ng purli ne calculati on and brace is set. Accord ing to the rules, whe n the purli n spa n more tha n 4 m, appropriate is set in the purli n across brace; A time spa n is more tha n 6 m in spa

13、n purli n three locati ons in each set a brace, also should be set at roof of batter brace and poles. At constant load. Under the action of live load and wind pressure, purlin flange compressi on and brace should be set on the purli n flange 1/3. Un der the wi nd sucti on un der the acti on of the p

14、urli n flange compressi on and brace does not guara ntee purli n flange lateral displaceme nt and tors ion un der, if can brace should consider when calculating constraint purlin flange, should now under the purlin flange 1/3 place to stay with the same Sett in gs, so the purli n desig n best double

15、 brace.2. Con ti nu ous purli n calculati onUsually choose Z type purli n, ope ning directi on toward the eaves. Since Z type purlin overlap forms are available, and it can be such a purlin assumed to continu ous artifacts.(1) using lap tha n simply supported con ti nu ous purli n Z purli n internal

16、 force distributio n is uni form, stiffness big, qua ntity of steel can be saved.(2) con ti nu ous purli n overlap overlap area exists in support n ested flabby phe nomenon, its stiffness is smaller tha n the cross-secti on stiff ness of the sin gle con ti nu ous purli n, therefore had a certa in mo

17、me nt release in the beari ng, the bending mome nt in the spa n have in creased.(3) continu ous purli n overall stability calculatio n is not yet perfect, the available roofi ng env elope on overall stability and brace support system.(4) continuous purlin bending moment is greater than the cross of

18、bending mome nt of the beari ng, beari ng capacity accord ing to the two overlapp ing area purli n bending modulus of the sum of the con siderati on is reas on able, can greatly save the steel qua ntity.(5) con ti nu ous purli n of the lap len gth should not be less tha n 10% spa n len gth, the lap

19、len gth accord ing to the bending mome nt distributi on of end spa n and middle spa n were con sidered, with overlapp ing end bending moment is not greater than midspan moment for the conditions to determine the lap length can make the design more economical and reas on able.(6) made roof purli n an

20、d Ion gitud inal compressive bar, si ngle purli n whe n can not meet the requireme nt of the beari ng capacity of double purli ne are available, and this method saves the qua ntity of steel.(7) con ti nu ous purli n beam conn ecti ons should be used with the roof and purlin plate bolt connection in

21、case of purlin local web buckling and overall overtur ning. Whe n high purli n web thick ness is larger fashi on should be added a thicker gasket to improve its beari ng capacity.(8) in gen eral, the desig n with a knee brace purli n, the ben eficial effect of the knee brace to the purli n and adver

22、se effects can cel each other out, may be con sidered n egligible, to simplify the desig nSecond, metope purli n1. The simply supported beam wall is calculatedUsually choose C purli n, ope ning towards accord ing to actual situati on. Wall beam with ope ning up com mon ly, but huma nly scaled mouth

23、un derside purli ne allows purli n ope ning dow nwards arran ged to meet the n eeds of the fixed frame.Wall beam desig n and roof purli n is similar, also want to con sider wallboard. Restricti on in brace. Is differe nt pan els are self support ing and self support ing two kin ds, accord ing to par

24、ticular case is particular an alysis. In additi on. Whe n wall beam desig n accord ing to the differe nt tectonic conditions want to consider the impact of dual bending plate. Accord ing to tech ni cal specificati on for the cold bending thi n-wall steel structure 8.3.1 and provisions that, on both

25、sides of the hang hang wallboard wall beam and side wall. On the other side can not preve nt the torsional deformati on of rod wall beam, but excludi ng double mome nt of impact? (that is, the opti on B = 0), but on ly the stre ngth of the wall beam calculati on at this time.For wi nd sucti on flang

26、e in the stability calculati on, like roofi ng purli ne, wallboard gen erally USES self tapp ing screw and purli n fixed, can thi nk outside wallboard can preve nt wall beam flange lateral in stability. Brace is set in the wall beam in side more econo mic tha n in creas ing the purli n secti on. For

27、 the beari ng wallboard, can be set up only in the in side of the brace. For non self beari ng 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 wall beam un der the acti on of vertical support. On top of th

28、e wall panel and win dow of the wall beam should be set at the same time suspension and straight poles, would transmit the force to rigid frame colu mn or wall frame colu mn, the bottom of the wall beam fixed on the low wall or wall battleme nts com mon ly, the overall stabilityguara nteed, so the a

29、rticle did nt set at the bottom of the wall beam suspe nsion and poles.Three, brace is setBrace is small, effect. Actually have purlin is pressed steel plate light deformatio n and tors ion, reduce the purli ne len gth calculati on, en sure the lateral stability of purlin. Brace general through bolt

30、s and purlin conn ecti on, brace and roof plate can effectively improve the fun cti on of purli n of the torsi on degree of whole and reduce the exter nal load caused by the reverse effect. Although un der the purli n flange n ear any brace has a great in flue nee on the flexural beari ng capacity of purli n, but whe n meet brace inten sity, stiff ness of the brace effect on bending and bending bearing capacity can be