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受静载荷梁的内力及变位计算公式 |
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符 号 意 义 及 正 负 号 规 定 |
简 图 |
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P——集中载荷 q——均布载荷 R——支座反力,作用方向向上者为正 Q——剪力,对邻近截面所产生的力矩沿顺时针方向者为正 M——弯矩,使截面上部受压,下部受拉者为正 θ——转角,顺时针方向旋转者为正 f——挠度,向下变位者为正 E——弹性模量 I——截面的轴惯性矩 |
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a、b、c——见各栏图中所示 |
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简 图 |
支座反力、 支座反力矩 |
区段 |
剪 力 |
弯 矩 |
挠 度 |
转 角 |
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RB=P MB=-Pl |
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Qx=-P |
Mx=-Px |
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RB=P MB=-Pb |
AC |
Qx=0 |
Mx=0 |
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CB |
Qx=-P |
Mx=-P(x-a) |
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RB=nP
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RB=ql
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Qx=-qx |
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RB=qc MB=-qcb |
AC |
Qx=0 |
Mx=0 |
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CD |
Qx=-q(x-d) |
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DB |
Qx=-qc |
Mx=-qc(x-a) |
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AC |
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CB |
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RB=0 MB=Mx=-M |
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Qx=0 |
Mx=-M |
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ω值见表梁分段的比值及ω的函数表; a、b、c——见各栏中所示 |
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简 图 |
支座反力、 支座反力矩 |
区段 |
剪 力 |
弯 矩 |
挠 度 |
转 角 |
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RA=RB= |
AC |
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CB |
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RA= RB= |
AC |
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CB |
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Mx=Pa(1-ξ) MC=Mmax=
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RA=RB=P |
AC |
Qx=P |
Mx=Px |
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CD |
Qx=0 |
Mx=Mmax=Pa |
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AC |
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CD |
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DB |
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若a>c:
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当n为奇数:
当n为偶数:
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当n为奇数:
当n为偶数:
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当n为奇数:
当n为偶数:
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当n为奇数:
当n为偶数:
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RA=RB =qa |
AC |
Qx=q(a-x) |
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CD |
Qx=0 |
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RA=RB = |
AC |
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CD |
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AC |
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CD |
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DB |
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RA=RB=qc |
AC |
Qx=qc |
Mx=qcx |
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CD |
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DE |
Qx=0 |
Mx=Mmax=qcb |
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当x=0.519l2
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AC |
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AC |
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CB |
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若a>b,
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Mx=M(1-ξ) Mmax=M |
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M0=M2-M1
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若M1>M2: Mmax=M1 |
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AC |
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Mx=Mξ MC左=Mα |
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CB |
Mx=-Mζ MC右=-Mβ |
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ω值见表梁分段的比值及ω的函数表; a、b、c——见各栏图中所示 |
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简 图 |
支座反力、 支座反力矩 |
区段 |
剪 力 |
弯 矩 |
挠 度 |
转 角 |
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AC |
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CB |
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当x=0.447l:
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AC |
Qx=RA |
Mx=RAx |
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CB |
Qx=RA-P |
Mx=RAx-P(x-a) |
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AC |
Qx=RA |
Mx=RAx |
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CD |
Qx=RA-P |
Mx=RAx-P(x-a) |
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DB |
Qx=RA-2P |
Mx=RAx-P(2x-l) |
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MC=Mmax=RAa |
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当x=0.422l:
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RB=qc-RA MB=RAl-qcb |
AC |
Qx=RA |
Mx=RAx |
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CD |
Qx=RA-q(x-d) |
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DB |
Qx=RA-qc |
Mx=RAx-qc(x-a) |
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当x=0.447l: Mmax=0.0298ql2 |
当x=0.447l:
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当x=0.329l: Mmax=0.0423ql2 |
当x=0.402l:
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AC |
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当x=0.415l: Mmax=0.0475ql2 |
当x=0.430l:
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MA=Mmax=M |
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AC |
Qx=RA |
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CB |
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MC右=Mmax =M+MC左 |
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ω值见表梁分段的比值及ω的函数表; a、b、c——见各栏图中所示 |
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简 图 |
支座反力、 支座反力矩 |
区段 |
剪 力 |
弯 矩 |
挠 度 |
转 角 |
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AC |
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反弯点在 及 |
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RA=RB=P
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AC |
Qx=P |
Mx=Pl(ξ-ωRα) |
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CD |
Qx=0 |
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AC |
Qx=RA |
Mx=MA+RAx |
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CB |
Qx=RA-P |
Mx=MA+RAx-P(x-a) |
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若a>b,当
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当n为奇数: 当n为偶数: |
当n为奇数: 当n为偶数: |
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当n为奇数:
当n为偶数:
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当n为奇数:
当n为偶数:
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反弯点在x=0.211l 及x=0.789l处 |
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RA=RB=qa
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AC |
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CD |
Qx=0 |
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AC |
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CD |
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RB=qc=RA
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AC |
Qx=RA |
Mx=MA+RAx |
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CD |
Qx=RA-q(x-d) |
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DB |
Qx=RA-qc |
Mx=MA+RAx-qc(x-a) |
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当x=0.548l: Mmax=0.0214ql2 |
当x=0.525l:
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AC |
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AC |
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CD |
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AC |
Qx=RA |
Mx=MA+RAx |
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CB |
Mx=MA+RAx+M |
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5.带悬臂的梁 |
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简 图 |
支座反力、 支座反力矩 |
区段 |
剪 力 |
弯 矩 |
挠 度 |
转 角 |
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RA=P(1+λ) RB=-Pλ MA=-Pm |
AC |
Qx=-P |
Mx=-Px |
当x=m+0.423l时:
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AB |
Qx=RA-P |
Mx=-Px+P (1+λ)(x-m) |
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RA=RB=P MA=MB=-Pm |
AC |
Qx=-P |
Mx=-Px |
当x=m+0.5l时:
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AB |
Qx=0 |
Mx=-Pm |
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AC AB |
Qx=-qx Qx=RA-qx |
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AC |
Qx=-qx |
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当x=m+0.423l时:
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AB |
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RA=RB=qm
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AC |
Qx=-qx |
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当x=m+0.5l时:
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AB |
Qx=0 |
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MA=-Pm
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AC |
Qx=-P |
Mx=-Px |
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AB |
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Mx=-Px+ RA(x-m) |
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AC AB |
Qx=-qx Qx=RA-qx |
当m=0.707l时: MB=0 |
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AC |
Qx=-qx |
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AB |
Qx=RA-qx |
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MA=M
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AC |
Qx=0 |
Mx=M |
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AB |
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Mx=-RA(x-m)+M |
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6.双跨、三跨梁 |
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OA |
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MO=MB=0
DE=AC=FG = |
两支点中间:
x=0.421l处:
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RA=(q1l1+q2l2) -(RO+RB)
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MO=MB=0
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MO=MC=0
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OA |
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AB |
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MO=MD=0
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x=0.447l处:
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RB= P1+P2-(RO+R2)
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MO=MD=0
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