意曲向为 q xm=Mh=48+428=4g+4yg =IDty1g+[R-R(8-sin 0)ly,g 2 O=106.3=1855ad 0 =3.14×1×001×7800×98+[3.14×0.53 5×0.(1.855-m106.39)×100098 q一均布力 =o(KM w) d226
26 L AL g A L g L V g L mg q 1 1 2 2 + = = = 106 3 1 855rad 0 = . = . Dt g R R g2 2 2 1 ( sin )] 2 1 = +[ − − = A1 1 g + A2 2 g = 9 (kN/m) 0.5 (1.855 sin106.3 )] 1000 9.8 2 1 3 14 1 0 01 7800 9 8 [3.14 0.5 2 2 − = . . . + − q — 均布力
INTERNAL FORCESIN BENDING 84-2 THE SHEARING FORCE AND BENDING MOMENT OF THE BEAM C I\ Internal force in bending: B Example Knowing conditions are P ●● a,1, as shown in the figure. Determine I the internal forces on the section at the P distance x to the end a X A B Solution:① Determine external forces Y R ∑ B X=0,XA=0 ∑ m,=0,R-Pa B ∑Y=0,Y 27
27 §4–2 THE SHEARING FORCE AND BENDING MOMENT OF THE BEAM 1、Internal force in bending： Example Knowing conditions are P， a，l , as shown in the figure. Determine the internal forces on the section at the distance x to the end A. a P P l YA XA RB A A B B Solution：①Determine external forces l P l a Y Y l Pa m R X X A B A A ( ) 0 , 0 , 0 , 0 − = = = = = =
意曲内为 §42梁的剪力和弯矩 、弯曲内力: C 举例已知:如图,P,a,l B 求:距A端x处截面上内力。 ●● 解:①求外力 P ∑X=0,∴XA=0 X A B Pa ∑m4=0,∴R Y R B ∑Y=0,:Y=-a) 28
28 §4–2 梁的剪力和弯矩 一、弯曲内力： [举例]已知：如图，P，a，l。 求：距A端x处截面上内力。 a P P l YA XA RB A A B B 解：①求外力 l P l a Y Y l Pa m R X X A A B A ( ) 0 , 0 , 0 , 0 − = = = = = =
INTERNAL FORCESIN BENDING (2 Determine internal forces P method of section A B ∑ Y=0,O=Y= P(l-a) R ∑m2=0,M=Yx B Shearing Internal forces of the orce b eam in bending M Bending C moment 1). Bending moment: M P Moment of the internal force couple with C the acting plane in the cross-section R B perpendicular to the section when the beam is bending 29
29 A B P YA XA RB m m x ②Determine internal forces— method of section m M Y x l P l a Y Q Y C A A = = − = = = 0 , ( ) 0 , A YA Q M RB P M Q Internal forces of the beam in bending Shearing force Bending moment 1). Bending moment：M Moment of the internal force couple with the acting plane in the cross-section perpendicular to the section when the beam is bending. C C
意曲内为 ②求内力截面法 P A B ∑Y=0,Q=Y=1-a) R ∑m=0,…M=Yx B 剪力 ∴弯曲构件内力 M 弯矩 C P 1.弯矩:M 构件受弯时,横截面上其作 C R 用面垂直于截面的内力偶矩。 B 30
30 A B P YA XA RB m m x ②求内力——截面法 m M Y x l P l a Y Q Y C A A = = − = = = 0 , ( ) 0 , A YA Q M RB P M Q ∴ 弯曲构件内力 剪力 弯矩 1. 弯矩：M 构件受弯时，横截面上其作 用面垂直于截面的内力偶矩。 C C