【正文】 構(gòu)件的承載能力和變形性質(zhì)與其所受荷載作用的時(shí)間特征有關(guān)，因此，對(duì)于不同性質(zhì)的試驗(yàn)，必須根據(jù)試驗(yàn)的要求制訂不同的加載制度。 22．對(duì)于受彎構(gòu)件，選取測(cè)量應(yīng)變的截面應(yīng)依據(jù)哪些原則？ 答：對(duì)于受彎構(gòu)件，需按如下原則選取測(cè)量應(yīng)變的截面： 1）彎矩最大處； 2）剪力最大處； 3）彎矩與剪力均較大處； 4）截面面積突變處； 5）抗彎控制截面（截面較弱且彎矩值較大處）； 6）抗剪控制截面（截面較弱且剪力值較大處）。 24．鋼筋混凝土梁受拉主筋的應(yīng)力可用哪兩種方法測(cè)量？ 答：鋼筋混凝土梁受拉主筋的應(yīng)力可用兩種方法測(cè)量：一種是預(yù)埋電阻應(yīng)變片法，另一種是在混凝土的表面預(yù)留孔洞（或稱窗口）。 26．如何確定鋼筋混凝土梁開(kāi)裂荷載實(shí)測(cè)值？ 答：確定鋼筋混凝土梁開(kāi)裂荷載實(shí)測(cè)值： 1）如果在 規(guī)定的荷載持載時(shí)間結(jié)束后出現(xiàn)裂縫，則將此級(jí)荷載定為開(kāi)裂荷載實(shí)測(cè)值。 3）如果沒(méi)有及時(shí)發(fā)現(xiàn)第一條裂縫，可取荷載 撓度曲線上的轉(zhuǎn)折點(diǎn)（曲線第一彎轉(zhuǎn)段兩端點(diǎn)切線的交點(diǎn)）的荷載值作為構(gòu)件的開(kāi)裂荷載實(shí)測(cè)值。但是由于測(cè)量誤差的存在，真值無(wú)法測(cè)得，只能用多次測(cè)量的算術(shù)平均值作為其近似值，測(cè)量次數(shù)越高，接近程度 越高，當(dāng)測(cè)量次數(shù)足夠多時(shí)，近似值趨于穩(wěn)定。振動(dòng)試驗(yàn)的目的是測(cè)定結(jié)構(gòu)的動(dòng)力特性、結(jié)構(gòu)的響應(yīng)及結(jié)構(gòu)的破壞特性等。 30．檢驗(yàn)性疲勞試驗(yàn)一般研究哪些內(nèi)容？ 答：檢驗(yàn)性疲勞試驗(yàn)，通常是在重復(fù)荷載作用下，經(jīng)歷 規(guī)定的荷載重復(fù)次數(shù)的荷載作用期間及之后，對(duì)下列內(nèi)容進(jìn)行檢驗(yàn)：1）抗裂性能； 2）開(kāi)裂荷載、裂縫寬度及開(kāi)展情況； 3）最大撓度的變化情況。 32．建筑結(jié)構(gòu)抗震試驗(yàn)按照試驗(yàn)方法和試驗(yàn)手段的不同，分為哪幾類？ 答：建筑結(jié)構(gòu)抗震試驗(yàn)按照試驗(yàn)方法和試驗(yàn)手段的不同，可以分為低周反復(fù)加載試驗(yàn)（偽靜力試驗(yàn)）、擬動(dòng)力試驗(yàn)和動(dòng)力加載試驗(yàn)。試驗(yàn)要求做到結(jié)構(gòu)構(gòu)件屈服以后，進(jìn)入非線性工作階段，直至完全破壞；試驗(yàn)要求同時(shí)觀測(cè)結(jié)構(gòu)的強(qiáng)度、變形、非線性性能和結(jié)構(gòu)的實(shí)際破壞狀態(tài)。低周反復(fù)加載試驗(yàn)的不足是由于對(duì)稱的、有規(guī)律的低周 反復(fù)加載與某一次確定性的非線性地震相差甚遠(yuǎn)，不能反映應(yīng)變速率對(duì)結(jié)構(gòu)的影響，所以無(wú)法再現(xiàn)真實(shí)地震的狀況。 請(qǐng)您刪除一下內(nèi)容， O(∩ _∩ )O 謝謝?。?！ 2021 年中央電大期末復(fù)習(xí)考試小抄 大全，電大期末考試必備小抄，電大考試必過(guò)小抄 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 games measures in (7576 cm) in circumference, and a women39。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 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。 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。 England in 1894。 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 in (10 cm) larger than a soccer ball. The dedicated basketball was made of laced leather and weighed less than 20 oz (567 g). The first molded ball that eliminated the need for laces was introduced in 1948。s basketball. Until World War II, basketball became increasingly popular in the United States especially at the high school and college levels. After World War II, its popularity grew around the world. In the 1980s, interest in the game truly exploded because of television exposure. Broadcast of the NCAA Championship Games began in 1963, and, by the 1980s, cable television was carrying regular season college games and even high school championships in some states. Players like Bill Russell, Wilt Chamberlain, and Lew Alcindor (Kareem AbdulJabbar) became nationally famous at the college level and carried their fans along in their professional basketball careers. The women39。s game. Television interest followed the women as well with broadcast of NCAA championship tourneys beginning in the early 1980s and the formation of the WNBA in 1997. Internationally, Italy has probably bee the leading basketball nation outside of the United States, with national, corporate, and professional teams. The Olympics boosts basketball internationally and has also spurred the women39。s basketball league in the United States was the National Basketball League (NBL), which debuted in 1898. Players were paid on a pergame basis, and this league and others were hurt by the poor quality of games and the everchanging players on a team. After the Great Depression, a new NBL was anized in 1937, and the Basketball Association of America was anized in 1946. The two leagues came to agree that players had to be assigned to teams on a contract basis and that high standards had to govern the game。s professional leagues were attempted and failed, including the Women39。s World Basketball Association, before the WNBA debuted in 1997 with the support of the NBA. James Naismith, originally from Almonte, Ontario, invented basketball at the International YMCA Training