Page 133 - Advanced Design Examples of Seismic Retrofit of Structures

Example of an RC Building Retrofitted by RC Shear Walls Chapter 3 125

TABLE 3.2 Results of the Qualitative Evaluations Phase

Parameters affecting l Serious changes in design codes since the 1960s
vulnerability and significant increase in the design-level
earthquakes
l Necessity of using ribbed bars in structural
members and modifications in the reinforcing
bars details
l Selected structural system considering the plan
dimensions and the number of stories
l Improper arrangement of structural members
l Arrangement of the RC shear walls in the plan of
the building and torsional forces
l Irregularities in plan and elevation
l Large openings in diaphragms
l Small distance between the two parts of the
building and the possibility of pounding during
earthquakes
l It was found that the DCR under gravitational
loads of a majority of the columns in the first story
in the southern building part is 0.7. This ratio is
even higher for the corresponding columns in the
northern building part
Causes of vulnerability of l Low strength columns
structural members l Low strength RC shear walls
l Reinforcing bars details
Causes of vulnerability of l Improper detailing of the large window
non-structural members

exceedance in 50 years or 475 years of returning period) and the Collapse
Prevention (CP) performance level in Earthquake-2 (2% probability of
exceedance in 50 years or 2475 years of returning period) should be provided.
The summary of the evaluations in this phase is presented in Table 3.2.
Based on the results above, the building is vulnerable to Earthquake-1 and
Earthquake-2. A more accurate determination of the vulnerability of the build-
ing is calculated after carrying out the field evaluation, material testing and
quantitative study. Details of material testing based on Instruction for Seismic
Rehabilitation of Existing Buildings (Code 360) [1] are presented in Table 3.3.

3.2.1 Field Testing
A complete set of standard testing of materials, structural details, soil condition,
and groundwater level were performed and the results are presented
briefly here.