【正文】 對于焊接結構，除應限制鋼材中的硫、磷的極限含量 外，還應限制 （ 碳 ） 的含量不超過規(guī)定值。 4． 在靜力或間接動力荷載作用下，正面角焊縫的強度設計增大系數(shù) β f=（ ） 。但對直接承受動力荷載的結構，應取 β f=（ ）。 5． 普通螺栓連接受剪時，限制端距 e≥ 2d，是為了避免鋼板被 （ 沖剪 ） 破壞。 6． 角焊縫中的最大焊腳尺寸 Hfmax=，其中 t為 （ 較薄 ） 焊件厚度。 7． 影響鋼結構構件及其連接的疲勞性能因素有構造狀況、 （ 應力幅 ） 和循環(huán)次數(shù)。 8． 軸心受壓構件整體失穩(wěn)的形式有 (彎曲失穩(wěn) )、 ( 彎扭失穩(wěn) ) 、（扭轉失穩(wěn) )。 9． 軸心受拉構件計算的內容有 (強度 )和剛度。 10． 計算雙肢格構式軸心受壓構件繞虛軸 x軸彎曲的整體穩(wěn)定時，其軸心受壓整體穩(wěn)定系數(shù) Ψ 應根據(jù) (換算長細比 )查表確定。 11． 焊接組合梁截面高度的確定應考慮三種參考高度，是指由建筑要求確定的最大梁高 。由（用鋼量最少） 確定的 （經(jīng)濟梁高） 。由剛度要求確定的最小梁高。 12． .鋼材中硫含量過多會引起鋼材的 （ 熱脆 ）； 磷含量過多會引起鋼材的 （ 冷脆 ）。 25 13． 當溫度從常溫下降為低溫時，鋼材的塑性和沖擊韌性 （ 降低 ）。 14． 當應力循環(huán)次數(shù)， n≤ 5 104次時， 應進行疲勞計算 。疲勞計算采用 （容許應力） 法，應力按彈性狀態(tài)計算。 15． 鋼板對接中，采取分段施焊，厚焊縫則分層施焊，工字形連接焊接時采用對稱跳焊，上述措施的目的在于 （減少焊接變形）。 ，可能發(fā)生彎曲屈曲和 （ 扭轉 ） 屈曲。 （殘余應力） 。而且 （殘余應力）對軸心受壓構件臨界力的影響最大。 ，如要改變截面，應在距支座約 （ L /6 ） 處改變截面較為經(jīng)濟。 19. 當荷載作用在 梁的 （ 下 ） 翼緣時，梁整體穩(wěn)定性提高。 ，當受壓翼緣側向支承點間距離越小時，則梁的整體穩(wěn)定就 （ 越好 ）。 (各種混凝土板和鋼板 )密鋪在梁的受壓翼緣上并與其牢固相連、能阻止梁受壓翼緣的側向位移，可不計算梁的 （整體穩(wěn)定） 22. 當上下弦橫向水平支撐設在第二柱間時，應在第一柱間設 （剛性系桿） 以傳遞山墻風荷載。 ，一般情況下隨著含碳量的增高，鋼材的塑性和韌性逐漸 （降低 ）。 ，鋼材的疲勞強度主要與構造狀況、應力幅和循環(huán)荷載重復次 數(shù)有關，而與鋼材的 （ 強度 ） 并無明顯關系。 ，當應力變化的循環(huán)次數(shù) （ n≥ 5 104次 ） 時，應進行疲勞驗算。 26 Basketball can make a true claim to being the only major sport that is an American invention. From high school to the professional level, basketball attracts a large following for live games as well as television coverage of events like the National Collegiate Athletic Association (NCAA) annual tournament and the National Basketball Association (NBA) and Women39。s National Basketball Association (WNBA) playoffs. And it has also made American heroes out of its player and coach legends like Michael Jordan, Larry Bird, Earvin Magic Johnson, Sheryl Swoopes, and other great players. At the heart of the game is the playing space and the equipment. The space is a rectangular, indoor court. The principal pieces of equipment are the two elevated baskets, one at each end (in the long direction) of the court, and the basketball itself. The ball is spherical in shape and is inflated. Basketballs range in size from in (7276 cm) in circumference, and in weight from 1822 oz (510624 g). For players below the high school level, a smaller ball is used, but the ball in men39。s games measures in (7576 cm) in circumference, and a women39。s ball is in (7274 cm) in circumference. The covering of the ball is leather, rubber, position, or synthetic, although leather covers only are dictated by rules for college play, unless the teams agree otherwise. Orange is the regulation color. At all levels of play, the home team provides the ball. Inflation of the ball is based on the height of the ball39。s bounce. Inside the covering or casing, a rubber bladder holds air. The ball must be inflated to a pressure sufficient to make it rebound to a height (measured to the top of the ball) of 4954 in ( m) when it is dropped on a solid wooden floor from a starting height of 6 ft ( m) measured from the bottom of the ball. The factory must test the balls, and the air pressure that makes the ball legal in keeping with the bounce test is stamped on the ball. During the intensity of high school and college tourneys and the professional playoffs, this inflated sphere mands considerable attention. Basketball is one of few sports with a known date of birth. On December 1, 1891, in Springfield, Massachusetts, James Naismith hung two halfbushel peach baskets at the opposite ends of a gymnasium and outlined 13 rules based on five principles to his students at the International Training School of the Young Men39。s Christian Association (YMCA), which later became Springfield College. Naismith (18611939) was a physical education teacher who was seeking a team sport with limited physical contact but a lot of running, jumping, shooting, and the handeye coordination required in handling a ball. The peach baskets he hung as goals gave the sport the name of basketball. His students were excited about the game, and Christmas vacation gave them the chance to tell their friends and people at their local YMCAs about the game. The association leaders wrote to Naismith asking for copies of the rules, and they were published in the Triangle, the school newspaper, on January 15,1892. Naismith39。s five basic principles center on the ball, which was described as large, light, and handled with the hands. Players could not move the ball by running alone, and none of the players was restricted against handling the ball. The playing area was also open to all players, but there was to be no physical contact between players。 the ball was the objective. To score, the ball had to be shot through a horizontal, elevated goal. The team with the most points at the end of an allotted time period wins. Early in the history of basketball, the local YMCAs provided the gymnasiums, and membership in the anization grew rapidly. The size of the local gym dictated the number of players。 smaller gyms used five players on a side, and the larger gyms allowed seven to nine. The team size became generally established as five in 1895, and, in 1897, this was made formal in the rules. The YMCA lost interest in supporting the game because 1020 basketball players monopolized a gymnasium previously used by many more in a variety of activities. YMCA membership dropped, and basketball enthusiasts played in local halls. This led to the building of basketball gymnasiums at schools and colleges and also to the formation of professional leagues. Although basketball was born in the United States, five of Naismith39。s original players were Canadians, and the game spread to Canada immediately. It was played in France by 1893。 England in 1894。 Australia, China, and India between 1895 and 1900。 and Japan in 1900. From 1891 through 1893, a soccer ball was used to play basketball. The first basketball was manufactured in 1894. It was 32 in (81 cm) in circumference, or about 4 i