如题图所示为一厚木屋架下弦接点，其木材顺纹承压强度设计值fc=10N/mm2，该杆轴向力设计值P=36kN，采用钢夹板连接，螺栓连接承载力的计算系数Kυ=7.5，木材斜纹承压降低系数
=1。试问接头所需φ20的最少螺栓数目为（）。
A．3
B．5
C．4
D．6
参考答案：C
解析：
应用《木结构规范》式(6.2.2)得每一剪切面的设计承载力
根据规范第6.2.4条的规定，当木材斜纹受力时要求降低系数
螺栓数
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| At one of the school in London, the students can go into town in the afternoon. But they must 1 to the school before six. One afternoon, Bob went to see a film. When he came back to the school, the school gate had already been closed. He went around the building to 2 door. That one was closed, too. Then he saw an open window on the 3 floor. It was the 4 office, Bob looked 5 the room, but no one was in. He quickly 6 into the room. Just then he heard a voice. Bob looked round and hid (躲藏) himself 7 a chair. Then the head teacher came in and sat down on the chair. He read a book for an hour. At last the head teacher stood up and went towards the door. "Thank goodness, he didn't 8 me." Bob thought 9 he left the room, the head teacher spoke to the chair, "Would you please 10 the lights when you leave?" | ||||
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