Milliy tadqiqot universiteti gIdrotexnik inshootlar va muhandislik konstruksiyalari kafedrasi

Materiallar epyurasini qurish tartibi.

Materiallar epyurasini qurishdan asosiy maqsad tashqi kuchlardan hosil bo‘ladigan eguvchi moment epyurasiga qarab bo‘ylama ishchi armaturalardan tejamli foydalanish maqsadida tayanchlargacha borishi shart bo‘lmagan ishchi armaturalarning nazariy qirqilish nuqtalarini aniqlash. So‘ngra esa qirqiladigan armaturalar uchun ankerlash uzunliklarini belgilab, ularning haqiqiy uzunliklarini aniqlashdir.

Materiallar epyurasi quyidagi tartibda quriladi:

1. 
   Millimetrli qog‘ozga masshtabda tashqi kuchlar bo‘yicha hisoblab topilgan eguvchi moment «M» va ko‘ndalang kuchlar «Q» epyurasi quriladi.
   
2. 
   Qabul qilingan ishchi armaturalardan qaysi biri to‘liq uzunlikda va qaysi biri qirqilishi belgilab olinadi (ularning diametri soni va armatura sinfi ko‘rsatiladi)
   
3. 
   Har bir ishchi armatura qabul qila oladigan birlamchi moment miqdorlari quyidagi formula yordamida hisoblab topiladi,
   

(4.31)

Topilgan M_si qiymatlari eguvchi momentlar qurilgan masshtabda to‘sinning bo‘ylama yunalishida to‘g‘ri chiziklar yordamida eguvchi moment epyurasiga joylashtiriladi. (4.4 rasm)

4.4-rasm. Materiallar epyurasini qurish sxemasi.

4. 
   Ishchi armaturalar qabul qila oladigan eguvchi moment «M_si» epyuralarini tashqi kuchlardan hosil bo‘ladigan asosiy eguvchi moment epyurasi bilan kesishgan nuqtalari (x₁, x₂, x₃, x₄, x₅) qirqiladigan armaturalarning nazariy qirqilishi nuqtalari deyiladi.
   
5. 
   Topilgan nazariy qirqilish nuqtalarining koordinatalari chiziqlarning tutashish nuqtalarning topish tenglamalari orqali analitik usulda hisoblab topiladi. Agar, epyuralar aniq masshtabda qurilgan bo‘lsa grafik usulda ham topilishi mumkin.Tayanchlar oralig’ida
   

; agar , a = q/2 =26,5/2 = 13,25 C=2 deb qabul qilinsa ,
bo’ladi
m
m
b/a =78,71/13,25 =5,94 m
tayanchning ustida , tenglamadan;

, tenglamadan;

Qirqilgan armaturalarning yuk ko‘tarish qobiliyatini kafolatlash maqsadida ularning nazariy qirqilish nuqtalaridagi uchlariga ankerlash uzunliklari l_an qo‘shiladi. Ularning qiymatlari quyidagi ifodalar orqali aniqlanib, ulardan kattasi qabul qilinadi.
(4.32)


XULOSA
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