CALCULUL STRUCTURII - PREDIMENSIONARE

CALCULUL STRUCTURII

PREDIMENSIONARE

1. Predimensionare stilpilor

Stilpii cadrelor sunt elemente supuse la solicitari compuse:M,N,T in proportii diferite,dupa pozitia lor in cadru.

Sectiunea transversala a stilpilor se alege de forma dreptunghiulara si circulara.

Dimensiunile sectiunii transversale se iau multiplu de 5 cm, pina la 80 cm si multiplu de 10 cm peste 80 cm.

Dimensiunea minima admisa este de 30x30 cm in situatii justificate dimensiunea minima se poate lua 25x25 cm.

Pentru asigurarea unei ductilitati corespunzatoare trebuie ca : A_b

unde :    R_c-rezistenta la compresiune a betonului ;

A_b=bxh -suprafata sectiunii transversale a stilpului ;

n-coeficient functie de pozitia stilpului in constructie :

n=0.35 stilp intermediar

n=0.30 stilp marginal

n=0.25 stilp de colt

N-efortul axial in stilp

Materiale folosite: B200 R_c=95 daN/cm²

PC52 R_a=2900 daN/cm²

Nⁿ=S_af*n_niv *q_n unde:

S_af-suprafata aferenta de descarcare a stilpului

n_niv-numarul de niveluri

q_n-incarcarea utila

S_af=5.4*5.4=29.16 m²

n_niv=3    T Nⁿ=29.16*3*835.6=73098.28 daN

A_b= cm²

b=h= T b=h=50 cm

2. Predimensionarea grinzilor

Inaltimea "h" a grinzii fata de deschiderea de calcul "l" este de obicei multiplu de 5 cm pentru hI cm si de 10 cm pentru h 80 cm.

h_min -pentru rigle si grinzi principale

h_min -pentru grinzi secundare

l=5040 cm T cm T h_min=40 cm

Se recomanda ca raportul dintre inaltime si latimea sectiunii transversale sa se ia I pentru elementele cu sectiune dreptunghiulara.

Inaltimea grinzii "b" are in mod obisnuit urmatoarele valori :

-pentru grinzi secundare 18,20,22 si max 25 cm

-pentru grinzi principale 25.40 cm

In final vom alege : h_g=60 cm si b_g=30 cm.

CALCULUL INCARCARILOR

CADRUL 3-3

5.4 5.4 5.4 4.5

E=300000 daN/m²

Stilpi : A=050*050=0.250 m²

Grinzi : A=0.3*0.6=0.18 m²

Calculul suprafetelor aferente cadrului 3-3

S₁ S₂

S₃ S₄

5.4 5.4 5.4 4.5

S₁=S₂= m²

S₃= m²

S₄= m²

Ipoteza 1: Incarcari permanente

A.Din greutatea planseului

pⁿ_gr.1= daN/m

pⁿ_gr.2== daN/m

pⁿ_gr.3== daN/m

pⁿ_gr.4== daN/m

pⁿ_gr.5== daN/m

pⁿ_gr.6== daN/m

pⁿ_gr.7== daN/m

pⁿ_gr.8== daN/m

pⁿ_gr.9= daN/m

pⁿ_gr.10= daN/m

pⁿ_gr.11= daN/m

pⁿ_gr.12= daN/m

B.Din greutatea grinzilor

pⁿ_gr.1=0.3*0.6*2500=450    daN/m

pⁿ_gr.2=0.3*0.6*2500=450    daN/m

pⁿ_gr.3=0.3*0.6*2500=450    daN/m

pⁿ_gr.4=0.3*0.6*2500=450    daN/m

pⁿ_gr.5=0.3*0.6*2500=450    daN/m

pⁿ_gr.6=0.3*0.6*2500=450    daN/m

pⁿ_gr.7= 0.3*0.6*2500=450 daN/m

pⁿ_gr.8=0.3*0.6*2500=450    daN/m

pⁿ_gr.9=0.3*0.6*2500=450    daN/m

pⁿ_gr.10=0.3*0.6*2500=450    daN/m

pⁿ_gr.11=0.3*0.6*2500=450    daN/m

pⁿ_gr.12= daN/m

C. Din greutatea stilpilor

pⁿ_gr.1=0

pⁿ_gr.2=0

pⁿ_gr.3=0

pⁿ_gr.4=0

pⁿ_gr.5= daN/m

pⁿ_gr.6= daN/m

pⁿ_gr.7= daN/m

pⁿ_gr.8= daN/m

pⁿ_gr.9= daN/m

pⁿ_gr.10= daN/m

pⁿ_gr.11= daN/m

pⁿ_gr.12= daN/m

D. Din pereti

pⁿ_gr.1=0

pⁿ_gr.2=0

pⁿ_gr.3=0

pⁿ_gr.4=0

pⁿ_gr.5= daN/m

pⁿ_gr.6=0

pⁿ_gr.7= daN/m

pⁿ_gr.8= daN/m

pⁿ_gr.9= daN/m

pⁿ_gr.10=0

pⁿ_gr.11= daN/m

pⁿ_gr.12= daN/m

E. Din atic

pⁿ_gr.1=5.4*467=2521.8    daN/m

pⁿ_gr.4=2.7*467=1260.9

daN/m

Total permanente pentru cadrul 3-3

qⁿ_gr1=1750.2+450+0+0+2521.8=4722    daN/m

qⁿ_gr2=1750.2+450+0+0=2200.2 daN/m

qⁿ_gr3=875.1+450+0+0=1325.1 daN/m

qⁿ_gr4=744.5+450+0+0+1260.9=2455.4    daN/m

qⁿ_gr5=1356.8+450+434.02+675=2915.82    daN/m

qⁿ_gr6=1356.8+450+434.02+0=2240.80    daN/m

qⁿ_gr7=678.5+450+434.02+85.25=1647.77    daN/m

qⁿ_gr8=577.125+450+520.83+511.5=2059.45    daN/m

qⁿ_gr9=1356.8+450+434.02+800=3040.82    daN/m

qⁿ_gr10=1356.8+450+434.02+0=2240.82    daN/m

qⁿ_gr11=678.5+450+434.02+85.25=1647.77    daN/m

qⁿ_gr12=577.125+450+520.83+252.87=1800.82 daN/m

Ipoteza 2 :Incarcari variabile-incarcari din zapada (STAS 10101/21-92)

pⁿ_z=c_e*c_zi*q_z unde :

c_e-coeficient care tine seama de conditiile de expunere a constructie

c_z-coeficient prin care se tine seama de aglomerarile de zapada de pe suprafata

constructie

a Tc_zi=1,00

q_z-greutatea de referinta a stratului de zapada

-pentru DOROHOI care este in zona C Tq_z=150 daN/m²

pⁿ_z=1*0.8*150=120 daN/m²

qⁿ_gr1= daN/m

qⁿ_gr2= daN/m

qⁿ_gr3= daN/m

qⁿ_gr4= daN/m

Ipoteza 3 :Incarcari variabile-incarcari utile

qⁿ_gr1= daN/m

qⁿ_gr2= daN/m

qⁿ_gr3= daN/m

qⁿ_gr4= daN/m

qⁿ_gr5= daN/m

qⁿ_gr6= daN/m

qⁿ_gr7= daN/m

qⁿ_gr8= daN/m

qⁿ_gr9= daN/m

qⁿ_gr10= daN/m

qⁿ_gr11= daN/m

qⁿ_gr12= daN/m

Ipoteza 4 : Incarcari variabile -incarcari din vint

pⁿ_v=b*C_n*C_h(z)*g_v    daN/m²

C_h(z)=0.65*^0.7

g_v=0.55 KN/m² =55 daN/m²

b

C_n=0.8

C_h(z)1=0.65*^0.7=0.32 =0.65

C_h(z)2=0.65*^0.7=0.32=0.65

C_h(z)3=0.65*^0.7=0.48=0.65

C_h(z)4=0.65* ^0.7=063=065

pⁿ_n1,2,3,4=1.6*0.8*55*0.65=45.76    daN/m²

Pⁿ_v=pⁿ_v*h_et*l_d=45.76*3*2.7=370.65    daN

Ipoteza 5: Ipoteza seismica

GLD1

GLD2

GLD3

5.4 5.4 5.4 4.5

m₁=182*2.7*3+293*6.4*3+0.3*0.6*2500*(2.7+2.7+2.7)+0.5*0.5*2500*(1.8+

+1.5)+456*5.4*2.7=19455.78 daN

m₂=0.3*0.6*2500*(2.7+2.7+2.7+2.7)+0.5*0.5*2500*(1.8+1.5)+456*5.4*5.4=

=20219.46

m₃=182*3*2.2+0.3*0.6*2500*(2.7+2.7+2.7+2.7)+0.5*0.5*2500*(1.8+1.5)+456

*(2.7*5.4+2.7*2.7)=18096.42

m₄=182*3*3+0.3*0.6*2500*(2.7+2.7+2.7)+0.5*0.5*2500*(1.8+1.5)+456*

*4.925*2.7=13409.16

m₅=182*3*5+0.3*0.6*2500*(2.7+2.225)+0.5*0.5*2500*(1.8+1.5)+456*2.7*

*2.225=9748.17

m₆=182*3*2.2+293*3*5.1+0.3*0.6*2500*(2.7+2.7+2.7)+0.5*0.5*2500*(1.5+1.5)

+456*5.4*2.7=17852.58

m₇=293*3*6.78+0.3*0.6*2500*(2.7+2.7+2.7+2.7)+0.5*0.5*2500*(1.5+1.5)+

+456*5.4*5.4=25991.58

m₈=182*3*2.2+0.3*0.6*2500*(2.7+2.7+2.7+2.7)+0.5*0.5*2500*(1.5+1.5)+

+456*(2.7*5.4+2.7*2.7)=17908.92

m₉=182*3*3.6+0.3*0.6*2500*(2.7+2.7+2.7)+0.5*0.5*2500*(1.5+1.5)+

+456*4.925*2.7=13549.26

m₁₀=182*3*5+0.3*0.6*2500*(2.7+2.225)+0.5*0.5*2500*(1.5+1.5)+456*2.7*

*2.225=9560.67

m₁₁=636.2*5.4*2.7+293*6.4*1.5+182*2.7*1.5+0.3*0.6*2500*(2.7+2.7+2.7)+0.5*

*0.5*2500*1.5+467*5.4=19929.99

m₁₂=636.2*5.4*5.4+293*1.5*6.78+0.3*0.6*2500*(2.7+2.7+2.7+2.7)+0.5*0.5*

*2500*1.5=27328.902

m₁₃=636.2*(2.7*5.4+2.7*2.7)+182*1.5*2.2+0.3*0.6*2500*(2.7+2.7+2.7+2.7)+

+0.5*0.5*2500*1.5=20311.794

m₁₄=636.2*4.925*2.7+182*1.5*3+0.3*0.6*2500*(2.7+2.7+2.7)+0.5*0.5*

*2500*1.5=13861.36

m₁₅=636.2*2.7*2.225+182*5*1.5+0.3*0.6*

+467*2.7=9601.62