Zbekiston respublikasi transport vazirligi qurilish muhandisligi fakulteti

1.12. Bosh to‘sinning chidamlilikka hisobi
Bosh to‘sin quyidagi kesimlarda hisoblanadi:
–kesim 03 (a_x=3,7 m).
Doimiy yukdan a_x=4.35 m va a_x=5.15 m kesimlarda sodir bo‘lgan eguvchi moment (1.4–rasm)
M_p= (n_pP_p+n P_p)W, (1.108)
bunda W = 0,5a (1–a). (1.109)
M_p= (1.1×27.5+1.2*30.368)*20.11=1341.16 kN m,
W = 0,5×4.35(13,6–4.35)=20.11 m².
Muvaqqat yukdan sodir bo‘lgan eguvchi moment
M_k=We_mk=20.11×0,5204×205=2145.37 kNm, (1.110)
bunda k'=205 kN/m – mustahkamlikka hisoblashda ruxsat etilgan muvaqqat yukning minimal qiymati.
Kuchlanish sikli asimmetriyasi:
beton uchun r_b =M_r / (M_r+M_k) =1341.16/(1341.16+2145.37)=0,3846; armatura uchun
r_s=0,15+0,8R_b =0,15+0,8×0,3846=0,4576.
Kuchlanish sikli asimmetriyasiga bog‘liq bo‘lgan koeffitsient: e_b=1,1422; e_sp=0,9103
Hisobiy qarshiliklar: R_bf=0,6×1,1422×14=9,59 MPa; R_sf =0.9103 × 240=218,472 MPa.
Siqilgan zona balandligi
× , (1.111)

(1,38)

Beton chidamliligi bo‘yicha ruxsat etilgan muvaqqat yuk /12. b.4.11/ (1.10–rasm)

, (1.112)
=113.705 kN/m.
Beton chidamliligi bo‘yicha a_x=4.35 m kesimda bosh to‘sin sinfi
K= =4.24.
Armaturaning chidamliligi bo‘yicha ruxsat etilgan muvaqqat yuk /12, b.4.11/ (1.10–rasm)
, (1.113)
=497.006 kN/m.
Armatura chidamliligi bo‘yicha a_x=4.35m kesimda bosh to‘sin sinfi
K= =18.55
–kesim SZ (a=5.15m)
Doimiy yukdan sodir bo‘lgan eguvchi moment
M_p=(27.5+30.368)*21.75=1258.629 kN m,
bunda W=0,5×5.15*(13.6–5.15)=21.75 m² .
x<0.5 bo‘lganda, muvaqqat yuk xissasi (1.52) formula bo‘yicha
e_M= 204,.
Muvaqqqat yukdan sodir bo‘lgan eguvchi moment (1.110) formula bo‘yicha
M_k=1258.629×0,5204×205=1342.73 kN m.
Kuchlanish sikli asimmetriyasi /12, b.2.1/: beton uchun r_b=1258.629/(1258.629+1342.73)=0.4838; armatura uchun /12, b.2.3/ r_s=0,15+0,8×0,4838=0,537
Kuchlanish sikli asimmetriyasiga bog‘liq bo‘lgan koeffitsientlar: e_b=1.1919; e_sp=0,9621.
Hisobiy qarshilik (R=14 MPa bo‘lganda):
R_bf=0,6×1.1919×14=10.01 MPa; R_sf=0,9621×240=230.904 MPa.
p' ning qiymatini /12, b.2.2/ga muvofiq p'=25 qabul qilamiz.

Inersiya momenti
I_Red=
Armaturaning chidamliligi bo‘yicha ruxsat etilgan muvaqqat yuk /12, b.4.11/
k= kN/m.
Armatura chidamliligi bo‘yicha a_x=5.15 m kesimda bosh to‘sin sinfi
K= =7.33
Beton chidamliligi bo‘yicha a_x=5.15 m kesimda ruxsat etilgan muvaqqat yuk
k= 465.9872 kN/m,
K= =17.394

1.10–rasm. Bosh to‘sinni hisoblash uchun q koeffitsientning qiymatlari