Evaluation of Seismic Response Trends from Long-Term Monitoring of Two Instrumented RC Buildings Including Soil-Structure Interaction

Table 5

Dependence of modal frequencies on PRA.

Mode	Direction	Model type	Modal frequency (y)–PRA (x) relationship^(*)	𝑅^2
Building A
1st	X	P/flexible base^(**)	𝑦=−20.67𝑥+3.44	0.80
		Flexible base	𝑦=−22.99𝑥+3.40	0.59
	Y	P/flexible base	𝑦=−11.42𝑥+3.42	0.53
		Flexible base	𝑦=−12.82𝑥+3.39	0.40
2nd	X	P/flexible base	𝑦=−22.57𝑥+3.74	0.59
		Flexible base	𝑦=−22.17𝑥+3.68	0.34
	Y	P/flexible base	𝑦=−11.72𝑥+3.73	0.47
		Flexible base	𝑦=−12.31𝑥+3.67	0.33
3rd	X	P/flexible base	𝑦=−15.02𝑥+3.85	0.63
		Flexible base	𝑦=−19.40𝑥+3.86	0.65
	Y	P/flexible base	𝑦=−8.68𝑥+3.84	0.51
		Flexible base	𝑦=−11.75𝑥+3.85	0.52
Building B
1st	X	P/flexible base	𝑦=−26.02𝑥+3.43	0.57
		Flexible base	𝑦=−26.83𝑥+3.38	0.55
	Y	P/flexible base	𝑦=−26.47𝑥+3.42	0.60
		Flexible base	𝑦=−27.42𝑥+3.37	0.59
2nd	X	P/flexible base	𝑦=−33.18𝑥+3.92	0.69
		Flexible base	𝑦=−31.97𝑥+3.88	0.43
	Y	P/flexible base	𝑦=−32.97𝑥+3.91	0.69
		Flexible base	𝑦=−31.09𝑥+3.87	0.43
3rd	X	P/flexible base	𝑦=−50.54𝑥+4.28	0.51
		Flexible base	𝑦=−54.80𝑥+4.29	0.58
	Y	P/flexible base	𝑦=−51.24𝑥+4.27	0.51
		Flexible base	𝑦=−54.14𝑥+4.27	0.56

^(*)Modal frequency in units of Hz, PRA in units of g.
^(**)P/flexible base = pseudoflexible base.