Software Development for Capacity Design of Earthquake Resistant Reinforced Concrete Plane Frames (RCPF)
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Date
2021-01-29
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Addis Ababa University
Abstract
Experiences from the response of structures during earthquakes and the nature of past
earthquakes themselves have taught designers that ductility is one of the important el-
ements in seismic resistant design. When a structure is said to be ductile it denotes
that the structure possesses the ability to dissipate energy through plastic deformations.
Designing buildings to resist earthquake induced forces elastically results in an uneco-
nomical construction. On top of that, the earthquake which the structure is designed to
withstand may not occur during its lifetime. But engineering is about economy as much
as safety. Generally speaking, structural design is nding a balance between these two key
elements and designing economical structures without compromising safety. Nonetheless,
in the process of signi cantly dissipating energy it may be necessary to accept some dam-
ages in predetermined locations. These locations are expected to possess the required
ductility and rotation capacities to exhibit the desired behaviour. Here is where the
strong-column-weak-beam concept comes into play which, as the name implies, bases its
philosophy on providing columns with exural capacities that are greater than that of
beams. This is to avoid soft storey failure that can a ect the stability of a structure; but
the failure of beams usually has a localized e ect. Shear capacities of members are also
to be greater than their exural capacities so that shear failure, a brittle failure, may not
precede the ductile and more preferable exural failure. The capacity design method is
based on these concepts.
In this research, software for the implementation of the capacity design process of re-
inforced concrete plane frames is presented. Design rules for capacity design were based
on those described in the 2015 Ethiopian Building Code (Speci cally ES EN 1990, ES EN
1992 and ES EN 1998). The software generally performs analysis, regular design and ca-
pacity design. It automates the reanalysis and redesign of failed members after increasing
their sections using the preset increment value. It also automatically converts continuous
reinforcement areas to discrete number of bars (or bar center-to-center spacings in case
of shear reinforcing) for the program determined bar diameter.
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Keywords
Capacity Based Design, Earthquake Resistant Design, Reinforced Con- crete Frame Design, Overstrength Factor, Ductile Frames, Capacity Design Software