Author :

Posted On :
To construct a design spectrum for a particular site, an estimate of earthquake ground motion is necessary. This is based on seismic history in the vicinity of the site.

**Estimating the ground motion**

To construct a design spectrum for a particular site, an
estimate of earthquake ground motion is necessary. This is based on seismic
history in the vicinity of the site. Unfortunately in many regions this
information is not available. Based on limited information, seismic risk
procedures and *attenuation* *relationship *for estimating the peak
ground acceleration (PGA) has been* *developed. From these studies it was
recommended that the ratio of peak velocity to peak acceleration *v*/*a*
be used to estimate the peak ground velocity and ratio of peak acceleration –
peak displacement product to the square of the peak velocity (*ad*/*v*^{2})
be used to estimate the peak displacement. A log normal distribution summary of
*v*/*a* and *ad*/*v*^{2} for records on four
different soil conditions is presented in Table 17.6. In the table *L*, *S*
and V denote the larger of two horizontal acceleration, the smaller of two peak
horizontal accelerations and the vertical component of the earthquake motion.
Using the *seismal risk map* and Table 17.6 one can estimate the maximum
ground motion at a site. This information is used to construct a site-specific
spectrum.

Example 17.9

Construct Newmark–Hall
broad-banded design spectrum for a site. Develop spectrum curves using the
program for damping factors 0.02, 0.05, 0.1. Estimate the maximum horizontal
ground displacement assuming the maximum ground acceleration = 0.4*g*,
assuming group L and 84.1% on 50 m alluvium by bed rock.

Solution

Maximum ground acceleration = 0.4*g*
= 0.4 × 981 cm/s^{2} = 392.4 cm/^{2}
From Table 17.6 *v*/*a* = 117/*g*; *ad*/*v*^{2}=
7.8

*v *= 117* *×* *0.4 = 46.8 cm/s

*d *= 7.8* v*^{2}/*a *=
7.8* *×* *46.8^{2}/392.4
= 43.53 cm

*a *= 392.4
cm/s^{2};* v *= 46.8 cm/s* d *= 43.53 cm

Construct the maximum ground
motion polygon with the values of *a*, *v* and *d*. Apply
appropriate amplification factors to the maximum ground motion* *components
in a manner similar to that described in the next pages.

Tags : Civil - Structural dynamics of earthquake engineering

Last 30 days 57 views
Related words : ### What is Estimating the ground motion Define Estimating the ground motion Definition of Estimating the ground motion where how
meaning of Estimating the ground motion
lecturing notes for Estimating the ground motion lecture notes question and answer for Estimating the ground motion answer
Estimating the ground motion study material Estimating the ground motion assignment Estimating the ground motion reference description of Estimating the ground motion
explanation of Estimating the ground motion brief detail of Estimating the ground motion easy explanation solution Estimating the ground motion wiki
Estimating the ground motion wikipedia how why is who were when is when did where did Estimating the ground motion list of Estimating the ground motion school assignment college assignment
Estimating the ground motion college notes school notes kids with diagram or figure or image difference between Estimating the ground motion www.readorrefer.in - Read Or Refer

Recent New Topics :
| Namespaces in C# |