Damage-Based Assessment for Performance-Based Design and Analysis of Timber or Wood Structure Under Earthquake Load

Damage-Based Assessment for Performance-Based Design and Analysis of Timber or Wood
Structure Under Earthquake Load
Submitted by:
Shreya Regmi
University of Melbourne

Abstract:
When an earthquake occurs, a lot of casualties and economic losses are experienced. The
structures used for the construction of the buildings determined a lot in regards to the extent of
loses which are experienced. The materials used for the construction of the structures can either
be steel, concrete, or timber, depending on the design. By definition, the damage of the
materials during earthquakes refers to the sudden or progressive deterioration, of the
mechanical strength of these materials when exposed to loading, chemical, or thermal effects.
Nonetheless, various models exist which helps in predicting these damages. They include
Displacement-Based Design (DBD): Forced-Based Design: and performance-based design. This
paper has, however, designed a new approach, damage based model, which is best suitable for
timber structures. In this paper, the recent numerical and experimental studies of timber
structures have been reviewed to find the probable gaps for future research.
Further, it has discussed some of the damage based models and narrowed down to the
Park-Ang Damage Model. The results indicate that the Park-Ang Damage Model is based on
hysteretic energy demands and normalized maximum displacements, usually in a linear form.
Thus, it is appropriate for the timber structures as it takes into consideration the cumulative
damage failure and the initial exceedance failure with regards to the determination of the
structural damage under earthquake.
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1. Introduction
Timber is originated from wood and is one of the oldest material used in the construction
industry, dating back the Stone Age Periods (Wood, 2017). Steel, timber and reinforced concrete
have been widely used in construction, but it has been understood that the confidence accorded
to timber structures is comparatively lower than the level of confidence granted to steel and
reinforced concrete structures (Miyake, Koshihara, Isoda, & Sakamoto, 2004). This is in terms of
the seismic response, and as such, the life cycle Costs of timber buildings is more than that of
concrete and steel buildings. However, the application of timber on structures has since
improved with the discovery of materials such as steel and concrete, resulting into development
of very modest structures.
The loads which are experienced by structures during an earthquake which originates
from ground acceleration forces of inertia is called the Seismic loads or Earthquake loads. The
magnitude of an earthquake depends on various factors like dynamic properties and mass of a
building, duration of an earthquake, intensity, and frequency of ground motion and the structures
and properties of soil that any structures are standing on. Regardless of the level of confidence
associated with timber buildings, research has indicated that these structures represent one of the
most significant investments human beings have ever made. In North America, research has
indicated that light frame buildings occupy about 80% to 90% (Folz & Filiatraut, 2005) of the
built environment, mainly because of the economics associated with timber. As with Japan, the
design of timber buildings is usually done according to seismic regulations, often revised after
several years. The design life of between 10 and 20 years has been the most significant, but
currently, most of the timber buildings were designed with the outdated specification. As with
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America, research has indicated that no proper seismic analysis has been done for the past 30
years, posing the country at significant anger when it comes to seismic activity.
Despite all the advantages of using timber as the primary construction material, it's
seismic response and behavior is yet to be understood fully. However, recent developments have
seen the seismic response of timber being thoroughly investigated. Hybrid buildings test, shaking
table tests and earthquake simulations, to mention a few, are some of the criteria that have come
to the fore when it comes to an understanding the seismic response of timber buildings.
Background
Steel is expensive while concrete has a significant carbon footprint on the planet. However, it is
understood that timber structures are some of the safest when it comes to occupancy protection.
This has been significantly attributed to the ratio of the weight to strength, which, as research has
indicated, is very high (Van Der Lindt, Pei, Liu & Fikiatraut, 2010). Moreover, there is the fact
that timber structures efficiently dissipate the energy from an earthquake because one of their
properties is nonlinear ductility. This nonlinear ductility proper, coupled with the ability to
dissipate earthquake energy, may also at times result in the destruction that may not conform to
design standard.
In its first test, the NEES project focused on a two-story building. This building has been
considered as a benchmark for all the seismic response tests and analysis that are being
conducted at present. In line with this, the experiment tried to focus on building configuration
and the response to seismic activity. Elements such as joints, bracing, and frame design are all
essential in the design of a building in a seismic prone region.
The shaking tables test has been of vital importance when it comes to seismic response
understanding. In line with this, the Building Research Institute has developed three proposals to
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improve the performance of timber structures. The first proposal is that of a composite structure
whose timber elements are supported by elements made from other materials. There is also the
aspect of joints and their importance to the overall building stability. These joints are a
conjunction of timber and other structural elements. Finally, there is the design of the general
building. Designing a hybrid structure made up of wood and the other construction materials
such as reinforced concrete is one of the viable proposals. All in all, various tests are being
conducted to come up with timber buildings that will be able to withstand shock waves, in line
with the performance-based criteria of building design.
Objective
The main objective of this study is to
1. Evaluate the performance of timber buildings by using a damage-based approach under
earthquake loads.
This paper identifies different damage models for concrete, steel, and timber structures. The
damage-based approach regarding the performance of timber buildings, when subjected to
earthquake loads, has been evaluated.
In this technique, the damping of the single degree of freedom and secant stiffness
determines the structure. By extension, this design relies on attaining a specific limit state of
displacement, ether characterized by non-structural drift limits or material strain limits
characterization by this design helps in preventing multiple problems associated with The
force-based design, (FBD) since the initial stiffness is employed in the determination of
elastic period.
Aims
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1. To explore how to shift from the displacement-based procedure to the damage-based
procedure
2. What we have to do to move from the displacement-based procedure to the damage-
based procedure and what is the current status.
3. To explore the existing damage models?
4. To explore the types of data sheets required for various damage models
To examine the types of systems or dynamic structural models required
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