【導讀】1．多余約束是體系中不需要的約束。2．如果體系的計算自由度大于零，那么體系一定是幾何可變體系。3．兩根鏈桿的約束作用相當于一個單鉸。5．兩剛片用三鏈桿相聯(lián)，且三鏈桿平行不等長，則構(gòu)成瞬變體系。6．圖示兩個單跨梁，同跨度同荷載。但橫截面形狀不同，故其內(nèi)力也不相同。7．三鉸拱的矢高f越大，水平推力也越大。8．求桁架內(nèi)力時截面法所截取的隔離體包含兩個或兩個以上的結(jié)點。9．某荷載作用下桁架可能存在零桿，它不受內(nèi)力，因此在實際結(jié)構(gòu)中可以將其去掉。10．試判斷下列彎矩圖是否正確。4．解：由三剛片規(guī)則，可知體系是無多余約束的幾何不變體系。1．靜定結(jié)構(gòu)由于支座移動引起的位移與剛度無關(guān)。2．反力互等定理僅對超靜定結(jié)構(gòu)才有使用價值。4．同一結(jié)構(gòu)的力法基本體系不是唯一的。六、求圖示桁架結(jié)點B的豎向位移，已知桁架各桿的EA=21×104kN。

　　

【正文】 EI 212hEI k11 21118mhEImk ??? 22211 181223 h EIh EIhEIk ???? 專業(yè)好文檔 If we don39。t do that it will go on and go on. We have to stop it。 we need the courage to do it. His ments came hours after Fifa vicepresident Jeffrey Webb also in London for the FA39。s celebrations said he wanted to meet Ivory Coast international Toure to discuss his plaint. CSKA general director Roman Babaev says the matter has been exaggerated by the Ivorian and the British media. Blatter, 77, said: It has been decided by the Fifa congress that it is a nonsense for racism to be dealt with with fines. You can always find money from somebody to pay them. It is a nonsense to have matches played without spectators because it is against the spirit of football and against the visiting team. It is all nonsense. We can do something better to fight racism and discrimination. This is one of the villains we have today in our game. But it is only with harsh sanctions that racism and discrimination can be washed out of football. The (lack of) air up there Watch mCayman Islandsbased Webb, the head of Fifa39。s antiracism taskforce, is in London for the Football Association39。s 150th anniversary celebrations and will attend City39。s Premier League match at Chelsea on Sunday. I am going to be at the match tomorrow and I have asked to meet Yaya Toure, he told BBC Sport. For me it39。s about how he felt and I would like to speak to him first to find out what his experience was. Uefa has opened disciplinary proceedings against CSKA for the racist behaviour of their fans during City39。s 21 win. Michel Platini, president of European football39。s governing body, has also ordered an immediate investigation into the referee39。s actions. CSKA said they were surprised and disappointed by Toure39。s plaint. In a statement the Russian side added: We found no racist insults from fans of CSKA. Baumgartner the disappointing news: Mission aborted. The supersonic descent could happen as early as Sunda. The weather plays an important role in this mission. Starting at the ground, conditions have to be very calm winds less than 2 mph, with no precipitation or humidity and limited cloud cover. The balloon, with capsule attached, will move through the lower level of the atmosphere (the troposphere) where our daytoday weather lives. It will climb higher than 專業(yè)好文檔 the tip of Mount Everest ( miles/ kilometers), drifting even higher than the cruising altitude of mercial airliners ( miles/ kilometers) and into the stratosphere. As he crosses the boundary layer (called the tropopause),e can expect a lot of turbulence. The balloon will slowly drift to the edge of space at 120,000 feet ( Then, I would assume, he will slowly step out onto something resembling an Olympic diving platform. Below, the Earth bees the concrete bottom of a swimming pool that he wants to land on, but not too hard. Still, he39。ll be traveling fast, so despite the distance, it will not be like diving into the deep end of a pool. It will be like he is diving into the shallow end. Skydiver preps for the big jump When he jumps, he is expected to reach the speed of sound 690 mph (1,110 kph) in less than 40 seconds. Like hitting the top of the water, he will begin to slow as he approaches the more dense air closer to Earth. But this will not be enough to stop him pletely. If he goes too fast or spins out of control, he has a stabilization parachute that can be deployed to slow him down. His team hopes it39。s not needed. Instead, he plans to deploy his 270squarefoot (25squaremeter) main chute at an altitude of around 5,000 feet (1,524 meters). In order to deploy this chute successfully, he will have to slow to 172 mph (277 kph). He will have a reserve parachute that will open automatically if he loses consciousness at mach speeds. Even if everything goes as planned, it won39。t. Baumgartner still will free fall at a speed that would cause you and me to pass out, and no parachute is guaranteed to work higher than 25,000 feet (7,620 meters). cause there