Makdisi & Seed Analysis

[moe333]

Sorry for the double post (seismology engineering), but thought some may not look in that forum.

I'm comparing seismic deformation of an embankment using the Makdisi & Seed approach to more recent methods by Bray et al (1997 and 2007). I am finding at least two different versions of charts for the Makdisi & Seed method. The one in the Kramer text has the period (To) of the embankment on one of the chart axes. The other version of the chart does not have To.

I have two questions for anyone familiar with these charts:

1) Do they both give the same answers?

2) One one of the charts where you need to compute Kmax as a function of the embankment and potential failure surface geometry, the horizontal axis has Kmax/PGA/g. Would you divide your PGA by g (32.2 fps^2) to come up with Kmax, or is this just indicating a divison by g to make Kmax dimensionless. I thought the latter, but have seen the the divison done in the Kramer text and it would obviously make a big difference.

Thanks

 

[jdonville]

Moe,

I have photocopies of both the 1977 and 1978 papers by Makdisi and Seed and cannot find a figure where one of the axes is labeled only 'To'. The dimensions of the axes in these figures is 'U/kmax g To'. Note that Figure 10 in the 1978 paper is plotted incorrectly - the corresponding figure in the 1977 paper should be used.

I have not performed a Makdis-Seed analysis for many years, so I am afraid that I cannot respond to your whole question more helpfully.

Jeff