问题 单项选择题

如题10~11图示一焊接工字形轴心受压柱的截面,承受的轴心压力设计值N=4500kN(包括柱的自重),计算长度ι0=7m、ι0y= 3.5m(柱子中点在x方向有一侧向支承)。翼缘钢板为剪切边,每块翼缘板上设有两个直径d0=24mm的螺栓孔。钢板为Q235 -B·F钢。柱截面几何特性:毛截面面积A=250cm2,净面积An =230.8cm2毛截面惯性矩:Ix=145 683cm4、Iy=41 667cm4、回转半径ix=24.14cm、iy=12.91mm。

柱截面整体稳定性验算中应力为()

A.178.9N/mm2

B.182.7N/mm2

C.191.7N/mm2

D.195.6N/mm2

答案

参考答案:D

解析:

按表5.1.2构件对x轴屈曲属6类截面,对y轴屈曲则属c类截面,因此根据λx和λy分别查附表3.2.3.3得:φx=0.939,φ( 下标)y=0.92<φ。

 

单项选择题
阅读理解

阅读下面的短文,并根据短文后的要求答题(请注意问题后的字数要求)。

     Quality after-school programs are designed to improve academic performance, decrease youth crimes

and other high-risk behaviors, and help young people grow into healthy, successful adults.

     The effect of quality after-school programs on academic performance is clear. Studies show that students

who take part in such programs show better work habits, higher rates of homework completion, improved

grades, and higher scores on achievement tests. They also have fewer absences and are less likely to blame.

After-school programs also influence high-risk teen behavior. Various studies show decreased rates of crime,

drug use, and teen sex among youth who join in well-run after-school programs when compared to similar

youth who do not. Finally, after-school programs play an important role in supporting the following fields of

development: physical, mental and social development. Thus, one can safely say that after-school programming

is an effective method to help young people become contributing members of society.

     Although there is enough proof from both small and large assessments that _____, it is important to note

that not all programs are equal. First, dosage (时量) matters-young people who attend the most hours over

the most years benefit more than members who attend less often or over a shorter period of time. Next, after-

school programs make a bigger difference for those students who need help most and have the fewest choices.

Finally, program qualities matter. After-school programs work best when they create unique opportunities for

youth. They should provide opportunities for positive rela- tionships, skill building, meaningful involvement,

expression, suggestion, service, and work. Staff char-acteristics make an important difference in the quality

of a program. The adults should treat youth as partners, create safe and fair environments, encourage

personalized involvement, and actively create learning opportunities. In short, although after-school programs

have promising future, how they are designed and run matters.

1. What is the best title for this passage? (within 10 words) 

    ______________________________________________________________________________________

2. Which sentence in the passage is the closest in meaning to the f'ollowing one? Quality of the program is to

    a great extent affected by the members' personality.  

    ______________________________________________________________________________________

3. What are the factors that affect the programs greatly? (within 15 words) 

    ______________________________________________________________________________________

4. Fill in the blank in Paragraph 3 with proper words or phrases. (within 20 words)  

    ______________________________________________________________________________________

5. Translate the underlined sentence in the last paragraph into Chinese. 

    ______________________________________________________________________________________