文档介绍：•..-DecreaseMethod283The80--decreasemethod,'10'}l'5''l'·ls',!2345(a)ABCDEfo-!'-----******@20'=80'--------"'--'--'-'--"=-}10'lsJ10''r'{-----:---=--:----:----';------Position11234510k20k20k30k30k---;.---:---=---:--:--------!!!!IPosition2234510k20k20k3ok30k----2L-_L-...L-_--L--l...IIIII_________'Position32345CASE1,(b)~13!:~_Influencelineformoment30kips20kips10kipsatpanelBl,s"l'1O',S,,*,10'1____..l_---'_L-_L_.,.....l1____L..-______Position15432~l---L-l~l~l--L.-(c)[continuesonnextpage]••••••284Chapter8LiveLoadForces:...·-kiploadatpanelB().Calculatethechangeinmomentasallloadsshiftleft10ft;thatis,load2movesuptopanelpointB(seeposition2).=(20+20+30+30)(l)(10)=+250kip-ft(loads2,3,4,and5)Decreaseinmoment10(-~)(to):::::-(change=+175kip-­tion3;thatis,(20+30+30)(5)(l)=+·ft(loads3,4,and5)Decreaseinmoment=(10+20)(5)(-~)=·ft(change=-·(numberinparentheses).MB=10()+20(15)+20()+30()+30(10)=-ftease2:'The30~-kiploadatpanelB().Computethechangeininomentasloadsmove5ftlefttoposition2..Incre