Birla Vishvakarma Mahavidyalaya (Engg. College)[An Autonomous Institution]

Seminar On:

IMPORTANCE OF NON STRUCTURAL ELEMENTS DURING EARTHQUAKE

Guided by : Dr. Snehal Mevada Prepared by : Mehul Doshi (16SE818)

CONTENTS• Introduction• Literature Review• Observations• References

Introduction of Non-structural Elements• Not going to take any buildings load• Designed structure safe but causalities due to fail of NSE• Codal provision for structural elements but no provision for NSE.• Classification of NSE: (1) Contents of the building: Functionally enabling the use of space like Furniture, Facilities & equipment & door-window (2) Appendages of the building: Projecting out from the building or

attached to their exterior surface (3) Services & Utilities: Items for facilitating essential activities in

the buildings

Mistaken as NSE1. Unreinforced Masonry walls: - Constructed after the frame is built so not going to any loads - Performance during earthquake2. Roof top water tank3. Lift shaft4. Staircase: - Connected to various RCC element - Attracts earthquake forces, Act as a diagonal braces - Gets damaged

Cost share of NSE in Buildings

Cost share graph of the Non structural elementsCost share in of NSE in different structure

Challenges to the NSE in a Building1. Inertia force in the NSE2. Deformation in the NSE

• Based on these two it can be classified as1. Force-Sensitive NSE2. Displacement-Sensitive NSE3. Force and Displacement-Sensitive NSE

Interaction between NSE & SE• Building shakes NSE shaken, but vise versa of this is possible?• Structural secondary system • Non structural secondary system• Mass of the NSEs decides interaction• Considerable interaction leads to Hybrid structure• Buildings modelled with both NSE & SE of response for combined

system

Effects of earthquake on NSE1. Acceleration Effect - Seismic design of the connection between NSE & SE is performed using force in NSE. - Force= Inertia (m*a) or Elastic (k*δ) - Difficult to analyze each NSE for acceleration - Floor Acceleration Response Spectrum

Effects of earthquake on NSE2. Displacement Effect: - NSE & SE both oscillating - Oscillation path foul with each other damage of NSE - Protection of NSE requires estimation of relative movement - NSEs are long; rest on minimum two support (1) both on same building at different height (2) one on a building the other on adjoining building (3) one on ground other on building

Different Location of Supporting SE

(1) (2) (3)

Effects of earthquake on NSE2. Displacement Effect: - Support point shaking different amount - Relative movement of the NSE - Supports are moving out or coming closer then compression or tension type relative displacement given by Iδ1I + Iδ2I - One support come closer & other go away then relative displacement [Iδ1I - Iδ2I ] - Both these should be < δ(accommodate) - Every displacement sensitive NSE should be checked at each level

Earthquake Resistant Design PhilosophyItems

Earthquake Resistant

Design Philosophy

Building Type

Level of Earthquake shaking

Low Moderate Severe

SEs

Current Normal No Damage Minor Damage No Collapse

Critical & Lifeline - - -

Revised Normal No Damage Minor Damage No Collapse

Critical & Lifeline No Damage No Damage Minor Damage

NSEs

Current Normal No Damage Some Damage -

Critical & Lifeline - - -

Revised Normal No Damage No Damage No Permanent damage

Critical & Lifeline No Damage No Damage No Damage

Expected Level of Performance of NSEs• Qualitative Ranges of NSEs: - Immediate use of Performance - Dysfunctional state Performance - Damage or Collapse Performance• Quantitative Ranges of NSEs: - To design NSE, necessity to know quantitative ranges - For force sensitive NSE- Acceleration transformed by SE to NSE - Floor response acceleration spectra is used for this - For displacement sensitive NSE- Relative displacement of SEs on which NSEs are supported

Safety of NSEs from Primary & Secondary hazards

Check for Force

NSES

Force Sensitive

Displacement Sensitive

Dominant DominantDesign for

both

Combined

DesignDesign

Check for Displacement

Safety of Force Sensitive NSEs• Massive & Stiff – tends to Slide, Rock or Topple - Sliding: Feq > μ*W, W*b> Feq*h - Rocking: Feq < μ*W, W*b < Feq*h C.G. not crosses leeward corner - Toppling: Feq < μ*W, W*b < Feq*h C.G. not crosses leeward corner• Connected to Horizontal SEs or Vertical SEs• Causes additional forces to SEs due to connection

Safety of Force Sensitive NSEs• Main strategy – Prevent it from sliding & increase its restoring

moment• Some NSEs can not be directly connected to SE but it is encased &

shroud is connected with SE• NSEs near wall – Hold back by connection with wall, NSEs in middle of

the room – connected with Slab• NSEs one over other secured by tying top element to ground in

mutually perpendicular direction• Small objects are not anchored individually, Strings, Front panel plates

& vertical spacer in chemical laboratory, Book shelves in library

Displacement Sensitive NSEs Protection• Safety against compression, tension & shearing is achieve by providing sufficient slack• NSE based on geometry: (1) Linear NSE: Supported by the SEs between ends (2) Planer NSE: Supported by the SEs along edges

(1) (2)

Classification of Protection strategies1. Non-Engineered (Based on concept) - To secure small & light NSEs - Not connected with SEs (Ex. Glasses, Crockery, Bottles on shelves & books on library shelves - String or front panel use to hold in position - Tying gas cylinder to wall with chain2. Pre-Engineered Practice: - Factory made objects & moderate size like cup-board - Connection details based on calculation , experiments on shake table & past earthquake experiences.

Literature Review• Mevada et. al. (2013) studied that Non-structural elements give poor performance during past

earthquake and observed that design provision should be developed for the NSE.• Investigated the seismic response of the NSE by time history analysis performed to obtain the

Acceleration & Displacement• Found that Non structural element experiences minimum displacement & acceleration at the

center of the first floor

Seismic Response of Non-structural elements (International Journal of Innovation in Engineering & Technology)

Literature Review• Gupta et. al. (2016) studied that various NSEs affect the behavior of

the SEs, influence is small if the NSE attached to SE is flexible.• Natural period of the structural system will be shorten. Generally

dynamic analysis of SDOF system is used • Distribution of storey shear in column may change which may sustain

more forces then that it was assumed due to behavior of the NSE and it is observed that the position of column should also be changed

Behavior of the NSE during an earthquake

(International Journal of Advanced Research in Science, Engineering and Technology)

Literature Review• Mondal & Jain (2005) studied that very less information are provided

in IS 1893 so IS code should include following Clauses1. Provision of seismic relative displacement2. Define force & displacement sensitive element3. Amplification of lateral force that increases with the verticle

location of the NSEs4. Importance factor of the NSE5. Parameter to take care the flexibility of NSEs• They have compared different code and give following statement:1. Horizontal force on NSEs are about 26% to 43%.2. Designed lateral forces of elements attached on roof ranges from

80% to 150% Design of NSEs : A review of codal provision (The Indian Concrete Journal)

Literature Review• Chandwell et. al.(2014) studied minimum design loads equation from ASCE/SEI 7 on NSEs which improved seismic performance of NSE. But observed that it will not give that much confidence for NSE at higher level of floor.• For NSE in which torsion & diaphragm deformation is not take into account in equation to find the force. Observed that torsional effect & diaphragm flexibility affect the horizontal distribution of Peak Horizontal Acceleration.• The assumption made in distribution of vertical & horizontal seismic demands on NSE do not articulate with recorded data & results and studied that about 50 & 84 percentile PVFA values increase lineaely from base to roof different from the constant distribution assumed in ASCE/SEI 7 EVALUATION OF ASCE/SEI 7 PROVISIONS FOR DETERMINATION OF SEISMIC DEMANDS ON NONSTRUCTURAL COMPONENTS (U S National Conference)

EVALUATION OF ASCE/SEI 7 PROVISIONS FOR

Literature Review• Ju & Young Jung (2013) studied that failure of piping system after

earthquake leads to subsequent shut down of hospital & observed that although it is design by UBC-97 & NEHRP but fails• Evaluated the static & dynamic characteristics of complex actual

piping system based on NFPA-13 & SMACNA guideline and observed that current piping system subjected to design lateral force based on UBC-97 was failed in both guideline and observed that mode shape of pipe system is different from building.

Evaluation of Performance Requirements for Seismic Design of Piping System International Journal of Civil, Environmental, Structural, Construction & Architectural Engineering

Observations• As cost share of NSEs in the newly constructed building is rising,

designing of them is very necessary.• Generally, more buildings are designed by thinking about structural

safety only although they have costly interiors.• About all the structural elements are included in code. But the

causalities is very large during earthquake as no designing clauses there for the NSEs & very less awareness among engineers, contractor & designer.• Although foreign-countries have also include these elements in their

codes but it is at very primary stage which will not give assurance against safety of the NSE.• The seismic behavior of the NSEs should be studied in detail.

References1. Earthquake Protection of NSEs in Building by C V R Murti2. http://www.eucentre.it/ 3. https://www.irmi.com/articles/expert-commentary/earthq

uake-performance-of-nonstructural-components4. http://

www.bvt.co.nz/faq-seismic-restraint-of-non-structural-building-elements/

5. https://www.nibs.org/resource/resmgr/BSSC/P-749_Chapter4.pdf

THANK YOU