For example, those single taxpayers with $5,000 of Social Security benefits in the example above would see their marginal tax rate on nonâSocial Security income boosted by 50 percent if their modified AGI was between $25,000 and $30,000 and by 85 percent if their modified AGI was between $34,000 and $36,000.
Three types of vault were commonly used: the barrel-vault, the groined or four-part vault, and the dome. The barrel-vault was generally semi-cylindrical in section, and was used to cover corridors and oblong halls, like the temple-cellas, or was bent around a curve, as in amphitheatre passages.
Best Answer: In all the reading I've done, I've only seen two types of vaults developed by the Romans. The tunnel (or barrel) vault spans between two walls, like a continuous arch. The cross, or groined, vault is formed by the intersection at right angles of two barrel vaults, producing a surface that has arched openings for its four sides and concentration of load at the four corner points of the square or rectangle.