【正文】 k和人群荷載 qk，欄桿重可折算在均布自重荷載內(nèi)）。 5． 正常使用極限狀態(tài)驗算的目的是什么 ? 驗算時荷載組合如何選擇 ? 答：正常使用極限狀態(tài)驗算的目的是為了保證結(jié)構(gòu)構(gòu)件在正常使用條件下，抗裂度、裂縫寬度和變形滿足規(guī)范的相應(yīng)要求，即滿足結(jié)構(gòu)構(gòu)件的適用、美觀和耐久性的要求。s public security bureau shows some 100 foreign visitors enjoyed the 72hour policy by the end of March, most of them from the United States, the United Kingdom and Germany. Chengdu also reported robust growth in its overall tourist industry last year. Official statistics show that it received some 150 million tourists last year, an increase of 28 percent from 2021. Around million came from abroad, an increase of 12 percent. Tota l revenue from tourism surpassed 133 billion yuan ($). During his visit to Kazakhstan in September, Chinese President Xi Jinping proposed that China and Central Asia join hands to build a Silk Road economic belt to boost cooperation. The idea has been widely echoed in Central Asian countries, being an encouraging blueprint for Chinese areas along the Silk Road that has linked Asia and Europe for more than 2,000 years. In the next three weeks, China Daily reporters will travel through the belt in China and in Kazakhstan, Uzbekistan and Turkey. They will show the progress and expectations of the countries, businesses and peoples on the route. Shaanxi the start of the ancient Silk Road has positioned itself as the new starting point for the development of the Silk Road Economic Belt, which will strengthen China39。s ancient indigenous religion, while Du jiang yan is considered to be the oldest functioning watercontrol project in the world. Chengdu ranked third in tourist facilities, management and services among 60 Chinese cities in a customer satisfaction survey released last year. But, Li added that efforts are still needed to develop more tourism products, improve English services and provide accurate translation of traffic signs and scenic billboards. Zhao Yun, chairwoman of British Chamber of Commerce Southwest China, told China Daily that his colleagues found the policy very convenient. A British client once flew here and stayed for just one day to check her ordered goods, she said. Zhao was born in Shanxi province, but she has lived in Chengdu for more than 10 years. My life was like a running race moving from place to place. I also lived in Beijing and Shanghai before, she said. But Chengdu is a place that you never want to leave once settling down. It is now my second hometown, she said. If the environment is further improved, the city will attract more people to visit and live, with the 72hour visafree policy and pelling conditions in transportation, culture, climate and cuisine, he said. Foreigners also gave positive feedback on the policy. A spokesman from Dell Inc said the pany has a global hub of operation in Chengdu, so the threeday visa has an immediate and positive influence on the pany39。 3） 裂縫控制驗算：底板也應(yīng)進行抗裂及裂縫寬度驗算，荷載組合同側(cè)墻。 3．普通預(yù)應(yīng)力混凝土構(gòu)件的基本工作原理是什么？ 答：預(yù)應(yīng)力混凝土結(jié)構(gòu)是指在外荷載作用之前，先對混凝土施加壓力，造成人為的應(yīng)力狀態(tài)，它所產(chǎn)生的預(yù)壓應(yīng)力能抵消外荷載所引起的部分或全部拉應(yīng)力。 （ √ ） 5．提高混凝土強度等級是減小鋼筋混凝土構(gòu)件裂縫寬度的有效措施。 二、選擇題 （每題 2分，共 20 分） 1． 有兩個截面尺寸、混凝土強度等級、鋼筋級別 均相同，配筋率 ρ不同的軸心受拉構(gòu)件，在它們即將開裂時 ( C ) （ A） ρ大的構(gòu)件，鋼筋應(yīng)力 σs小 （ B） ρ小的構(gòu)件，鋼筋應(yīng)力 σs大 （ C） 兩個構(gòu)件的鋼筋應(yīng)力 σs均相同 2． 條件相同的先、后張法軸拉構(gòu)件，當 ?con及 ?l相同時，預(yù)應(yīng)力筋中應(yīng)力 ?peII （ B ） （ A）兩者相等 （ B）后張法大于先張法 （ C）后張法小 于先張法 3．對構(gòu)件施加預(yù)應(yīng)力的主要作用是 （ B ） （ A） 減輕構(gòu)件的自重 （ B） 提高構(gòu)件的抗裂度 （ C） 提高構(gòu)件的承載力。 2．在其它條件相同時，配筋率越高，平均裂縫間距越 _小 __，平均裂縫寬度越 _小 _，其它條件相同時，混凝土保護層越厚，平均裂縫寬度越 __大 _____。（ fc=10N/mm2 fy= yf? =310N/mm2 ， a=a?=40mm， % ?? ， ξ b=）（ 15 分 ） 解： （ 1）判別大小偏心受拉 mmahmmmNMe ??????? ； 所以按小偏心受拉構(gòu)件設(shè)計。39。 五、計算題 ，截面尺寸 b h=300 600mm，承受軸向力設(shè)計值 N=500KN，彎矩設(shè)計值 M=190KN （ √ ） 8．在偏心受壓構(gòu)件中，若偏心距較大，且受拉鋼筋配置不太多時會發(fā)生受拉破壞。s （ C） As=A39。)]/（ fcbh02）＜ 0的情況時，說明 （ A ） （ A） A39。 7． 區(qū)別大小偏心受壓的關(guān)鍵是遠離軸向壓力一側(cè)的鋼筋先 屈服 ，還是靠近軸心壓力一側(cè)的 混凝土 先 被壓碎 。 ２ ． 鋼筋混凝土軸心受壓短柱在整個加荷過程中，短柱 全 截面 受壓，其 極限 壓應(yīng)變是 均勻的 。)45435(310)(mmahfbhfMAycsbds????????????? ?? （ 4）求 As 239?；炷翉姸鹊燃墳?C20，鋼筋為 Ⅱ級。39。 4． 簡述梁的抵抗彎矩圖的概念，它與設(shè)計彎矩圖的關(guān)系？ 答：抵抗彎矩圖又稱材料圖，它是以各截面實際縱向受拉鋼筋所能承受的彎矩為縱坐標，以相應(yīng)的截面位置為橫坐 標，作出的彎矩圖。 ( ) 9．當ρ給定時，鋼筋的屈服強度 fy越高，開裂彎矩 Mcr 就越大。 10．無腹筋梁斜截面受剪破壞形態(tài)主要有三種，這三種破壞的性質(zhì) ( A ) (A)都屬于脆性破壞 (B 剪壓破壞和斜壓破壞屬于塑性破壞，斜拉破壞屬于脆性破壞 (C)