问题描述:
如下图所示,以壳单元模拟的剪力墙连梁指定同一连梁标签“SS”。在墙体自重荷载的作用下,沿连梁长度线性变化的剪力图与预期结果一致,但弯矩图却并非预期的“两端负弯矩,跨中正弯矩”的抛物线形状。请问,ETABS 显示的连梁弯矩图为何会是(水平)直线呢?
解答:
对于指定同一墙肢或连梁标签的多个壳单元,ETABS 在输出内力值或显示内力图时,仅考虑墙肢的顶端和底端或连梁的左端和右端的内力值。在此基础上,墙肢或连梁内部的内力值根据端部值进行线性插值,即:直接连线两端内力值。由于自重荷载作用下的连梁剪力沿长度方向恰好为线性变化,故 ETABS 采用的线性插值与预期结果一致。但是,对于连梁弯矩,简单的线性插值无法匹配实际的抛物线形弯矩图,故导致【问题描述】中提及的直线形弯矩图。
ETABS 采用上述方法输出和显示墙肢或连梁内力,其优势在于高效快捷,可以有效避免繁琐重复的内力合成。这种方法对于地震荷载起控制作用的内力输出和显示并不存在问题,因为集中于楼层标高处的地震力并非沿高度或长度分布的线荷载,故墙肢和连梁的弯矩图多为线性变化且最大弯矩值往往出现在端部。
回到【问题描述】中的剪力墙连梁,如果沿连梁长度方向指定更多的连梁标签(如:S1~S12),ETABS 也可以通过分段线性的形式显示预期的的连梁弯矩图,如下所示。不过,这种处理方法不利于后续的剪力墙设计,故不推荐使用。
![](data:image/png;base64,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)