*Cloudy sky* 22513 ارسال شده در 1 آبان، 2012 keystone : سنگ سرطاق A keystone is the wedge-shaped stone piece at the apex of a masonry vault or arch, which is the final piece placed during construction and locks all the stones into position, allowing the arch to bear weight 4
*Cloudy sky* 22513 ارسال شده در 2 آبان، 2012 non bearing wall : دیوار غیر باربر Excluding the independent garden variety, the nonbearing wall appears only where loads are carried by other members, as in heavy timber and other skeletal structures. 4
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