问题 单项选择题

某T形梁翼板所构成的铰接悬臂板,如图所示,桥面铺装层为2cm的沥青混凝土面层(重力密度为23kN/m3)和平均厚9cm的C25混凝土垫层(重力密度为24kN/m3),T形梁翼板的重力密度为25kN/m3。计算荷载为公路-Ⅰ级,汽车荷载冲击系数μ=0.3。结构安全等级为二级。

提示:按《公路桥涵设计通用规范》(JTG D60—2004)及《公路钢筋混凝土及预应力混凝土桥涵设计规范》(JTG D 62—2004)解答。

每米宽铰接悬臂板的根部由车辆荷载产生的弯矩标准值MAq(kN·m)、剪力标准值VAq(kN),与下列何项数值最为接近()。

A.-14.2;28.1

B.-15.8;29.0

C.-10.9;21.6

D.-12.4;24.5

答案

参考答案:A

解析:

解答如下:

查《公路桥涵设计通用规范》表4.3.1-2,后车轮着地长度a1=0.2m,着地宽度b1=0.6m。

a=a1+2h=0.2+2×0.11=0.42m

b=b1+2h=0.6+2×0.11=0.82m

由《公路钢筋混凝土及预应力混凝土桥涵设计规范》4.1.5条,单个车轮:a=a1+

故后车轮的有效分布宽度有重叠,则:

故作用于每米宽板条上的弯矩标准值、剪力标准值,按2个车轮轴重计算。

须判断后车轮的有效分布宽度是否有重叠,当单个车轮,a=a1+2h+2c>d=1.4m时,必重叠。

单项选择题
单项选择题

The first and most important agents of socialization are the people who care for infants. In the earliest months, messages from nurturers constitute the child’s basic understanding of the world around it. This is the infant’s first introduction to the language that shapes perception and elicits emotion.
Another powerful source of information and socialization is the friendship of peers. Peers are equals that one can deal with on the same level as oneself, whereas parents are superiors. The heavy emotional overlay of family relationships makes some kinds of learning difficult.
Much formal socialization is placed in the hands of professionals. Teachers from kindergarten on are specifically designated agents of socialization. Ideally, a teacher is one who has both knowledge and the skills to present it. During the course of teaching their subjects, classroom instructors provide role models and attempt to convey the excitement of learning itself.
In earlier times, parents, friends and teachers would comprise the list of primary childhood socializers. Children’s books, comics and magazines might also have been mentioned as sources of information on norms and role models. Today one must add three powerful indirect or non-personal socialization agents: radio, movies and television. Many people learn about politics, form a vision of well-being, and develop attitudes towards others from what they see on the screen and hear through the speakers.

The author’s chief agents include the following EXCEPT the ______.

A.family

B.group

C.school

D.internet