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