Page 51 - Advanced Design Examples of Seismic Retrofit of Structures

Example of a Two-Story Unreinforced Masonry Building Chapter 2 43

TABLE 2.2 Mass Per Unit Area of Jack-Arch Diaphragm
2
Mass Thickness (m) Mass (kg/m )
Density Floor First Floor First
3
Item (kg/m ) Story Story Story Story
Isolator 15 a 1.000 b – 15 –
Cement mosaic 2250 – 0.025 56
Asphalt 2200 a 0.080 – 176 –
Asphalt shingles 15 a 1.000 b – 15 –
Sand-cement 2100 0.030 0.030 63 63
mortar
Porous aggregate 1700 0.100 0.100 170 170
Brickwork with soil- 1750 0.100 0.100 175 175
gypsum mortar
Soil-gypsum mortar 1600 0.030 0.030 48 48
Gypsum mortar 1300 0.005 0.005 7 6.5
IPE 200 23 c 1.000 1.000 23 22.4
Total 730 540
a 2
The unit is kg/m .
b 2
The unit is m .
c
The unit is kg/m.

2.5.4 Irregularity
The building under study should be checked for its regularity against several
criteria which are as follows.

2.5.4.1 In Plan (Horizontal)
One of the main categories for evaluation of buildings irregularity is in their
plan. This category is divided into several subcategories, each dealing with a
condition which can ultimately result in poor seismic response of buildings
and as a result, better to be avoided or to reduce the effects of irregularity as
much as possible.

Geometrical
Based on ASCE 41, there are no changes in the net horizontal dimension of the
seismic-force-resisting system of >30% in a story relative to adjacent stories,