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An Optimized Solution
for Soft Storey Problem
of Non-Engineered RC frame Buildings
in Nepal
Presenter: Kishor Timsina
11th December 2018
Vizag, India
International Workshop on
Disaster Mitigation and Management
Personal Introduction
Name: Kishor Timsina
Masters Student, The University of Tokyo, Japan.
Research Interest: Structural Engineering
Research Title: Optimized Solution for Soft-Storey Problem for RC frame
Buildings in Nepal
Experience:
4 years with National Society for Earthquake Technology-Nepal
– Building Code Implementation in Municipalities of Nepal
– Detailed Damage Assessment after 2015 Earthquake
– Different activities for Earthquake Risk Reduction
Soft storey damage due to open mid storey
Soft storey damage due to commercial shutter at
ground floor
Soft storey damage due to commercial
shutter at ground floor
Gorkha Earthquake 2015
Soft storey damage due to commercial shutter at ground floor Soft storey damage due to commercial shutter
at ground floor
Gorkha Earthquake 2015
Gorkha Earthquake 2015
Gorkha Earthquake 2015
Our Buildings…
Social need
Culture and Lifestyle
(Business and parking)
Economical
Promotion system
Background
Technical need
Methodology
Material Availability
Socio-Technical
Problem
Buildings in Nepal 2015 Gorkha Earthquake Current Scenario
Assumption
Problem Statement:
This research studies on the soft storey problem due to business space/ parking in the ground floor
of RC frame with infilled masonry incorporating socio-technical aspect.
Social Review
Average no. of storey Purpose of open storey
Cause of Non-Retrofitting Desired Performance LevelAwareness of People
Total 35 professional Engineers working in 20 different municipalities of Nepal working for
design and construction of buildings.
Building Construction
Scenario Per Year
Shutter
length≥ 3m.
91.40%
5.70%2.90% ≤3
storey
3-6
storey
≥6
storey
68.60%
22.90%
8.50% Life safety during
large earthquake
Serviciability
after large
earthquake
Not Known
2.90%
20%
62.90%
14.30%Many
Few
Very Few
None
(MMI IX)
(MMI IX)
2.90%
25.70%
68.60%
2.90% Parking of
vehicles
Renting other
for buisiness
Business and
residence
Family
business
Technical Review
a. Soft storey b. With infill
wall
c. Strengthening all
Columns and Beams
d. Strengthening all
Columns and Beams
of open floor
e. Strengthening
Columns only
g. Increase capacity
according to the infill
f. Strengthening
Columns and
increasing shear
capacity of Beam
h. Steel Bracing
i. RC Shear wall j. Steel plate jacketing
Low Performance
High Cost
Low Material Availability
Low Usability
Result from AEM simulation
With infill wall
RC shear wall
(b) infill wall
(a)
(i)
(b)(i)
(a)
(e)
Research Objectives and Expected Outcomes
Objective:
To provide a practical and feasible solution for soft storey problem by optimizing RC
infill wall according to the Performance, Cost, Usability numerically in AEM.
Research Outcomes:
Development of an optimization methodology for RC infill wall according to
Performance, Cost, Usability .
Improvement of AEM modeling tool for analysis of RC frame with infill masonry
(2-D) incorporating soft storey.
Development of guidelines for design and implementation.
3. Provide the design
tool for retrofitting a
soft storey building with
a socially acceptable
solution.
1. Incorporation of
optimization scheme in AEM to
minimize the cost of retrofitting
using reinforced concrete
subjected to social and
technical constraints.
Methodology
Non-linear constrained
problem.
Implicit performance
criteria.
Iterative and dynamic.
Non-Linear Sequential
Quadratic Programming
(NLSQP)
Incorporating
constraints based
on social
requirements in
AEM.
2. Identify the
constraint
parameters based on
social requirements.
Another survey
with primary
stakeholders.
Background ReviewObjectives and
OutcomesMethodology Preliminary Results Timeline 6
Optimization
Objective Function: Min. F(x)= Cost
-Concrete cost -Reinforcement cost -Human resource cost
-Business disturbance cost
Subject to Constraints:
1. Performance Constraints:
-Life safety- Collapse prevention (at MMI IX) i. inter-storey drift
2. Usability Constraints:
i. Business Constraints:
-Area of the opening
ii. Parking Constraints:
-Height, width, and angle of opening based on size of vehicle
3. Complexity Constraints:
-Opening shape -Reinforcement detailing -Thickness of wall
-Min. length and height of concrete from frame -Formwork placement
Initialize
[x1, x2, x3, x4
, x5 , x6 , x7]
Step:1
AEM analysis
- Obtain
performance
criteria
Step:2
Step:3
Step:4
ith iteration
variable values
Optimized
Solution
Step:5
Convergence
[x]i≈[x]i-1[x]i≠[x]i-1
Step:1
Step: ith
Step: i+nth
Background ReviewObjectives and
OutcomesMethodology Preliminary Results Timeline 7
Optimization Flow
Fig. (a)- Soft Storey Problem
Fig. (b)- RC shear wall retrofitted
Fig. (c)- Opening with certain shape function
Fig. (d)- Increasing the opening with
optimization function
Fig. (e)- Optimized solution
Fig. (f)- Solution for design purpose
Recap Research Framework Optimization AEM Implementation Timeline
My Research
Socio-Academic
Bridging Institutes
Social Problem
House Owners and
Community People
Government
Authority
Masons and
Engineers
Awareness
Institutionalization
Vendors
Technical Supply
Product
Supply
Demand
Creation
Output
10
Thank You!!!
Iter. a b cost
1 1 0.5 10263.8
2 3.0000 0.5071 6102.45
3 3.0171 0.5212 6010.85
4 3.0378 0.5393 5895.88
5 3.0555 0.5533 5801.23
6 3.0755 0.5692 5693.14
7 3.0957 0.5852 5583.18
8 3.1110 0.5949 5506.78
9 3.1264 0.6047 5429.27
10 3.1497 0.6269 5287.86
Preliminary Results
1st Iteration 10th Iteration
Background ReviewObjectives and
OutcomesMethodology Preliminary Results Timeline 8
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