Bull Earthquake Eng DOI 10.1007/s10518-013-9561-1 ORIGINAL RESEARCH PAPER

On the seismic performance of bamboo structure S. Elizabeth · A. K. Datta

Received: 19 February 2013 / Accepted: 20 November 2013 © Springer Science+Business Media Dordrecht 2013

Abstract While the earthquake resistant building design and construction code has been developed in sophisticated national/city level, the implementation at the local level has been more of an exception than the rule. Other than concrete and steel, one such material that can be used in construction in the seismic zone area of the developing countries like India, especially in the northeast states, is bamboo, where bamboo is available in abundant. Bamboo’s light weight and relative flexibility make it a particularly attractive alternative for residential construction in seismic regions. Compared on a mass-per-volume basis to concrete, steel and wood, bamboo is second to concrete for strength, and ranks first for stiffness. As strong as mild steel with the compression strength of concrete, amazingly, one inch of bamboo can hold up to 7 1/2 tons of weight. This present study is an attempt to implement bamboo construction in Manipur which is regarded as one of the most seismically active regions worldwide. In this work, a bamboo housing system and a reinforced concrete frame structural system was modeled using finite element analysis program SAP, considering the model structures to be taken from the types of building that is built in Manipur. A parametric study is conducted to investigate the seismic performance of the structures and El-Centro Earthquake and Kobe Earthquake recorded excitation are used for input in the dynamic analysis on the models. The study has revealed that the bamboo structures are performing better in earthquake than the commonly built RC residential building. The behavior of the bamboo structure modeled in this present study gives an opportunity to accept bamboo as a construction material in seismic zone areas. Keywords

Bamboo · Reinforced concrete buildings · Modeling · Structural analysis

1 Introduction Manipur is one of the northeastern states of India which has been identified as the zone of most severe seismic hazard (i.e., zone V). This region has experienced several strong

S. Elizabeth (B) · A. K. Datta Department of Civil Engineering, National Institute of Technology, Durgapur, West Bengal, India e-mail: [email protected]

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Manipur

State/region

Area %

Growing stock %

North East

28.0

66

Madhya Pradesh

20.3

12

Maharashtra

9.9

5

Orissa

8.7

7

Andhra Pradesh

7.4

2

Karnataka

5.5

3

Others

20.2

5

Fig. 1 Availability of bamboo in India

magnitude earthquakes which have caused immense damage to life and property. The past seismicity data show that the northeast region has experienced more than 2,000 earthquakes of magnitude, Mw C 4.0, spanning a period of 140 (1866–2007) years. Most of the loss of life in past earthquakes has occurred due to the collapse of buildings, which were not particularly engineered to be earthquake resistant. In view of the continued use of such buildings in most countries of the world, it is essential to introduce earthquake resistance features in their construction. While the earthquake resistant building design and construction code has been developed in sophisticated national/city level, the implementation at the local level has been more of an exception than the rule. Other than concrete and steel, one such material for future that can be used in construction in the seismic zone area of the developing countries like India, especially in the northeast states, is bamboo, where bamboo is available in abundant (Fig. 1) and the material is very familiar to the people of Manipur. In these recent years, the importance of bamboo as a construction material, particularly for housing, has received renewed attention. Now many researches are going through for bamboo. Many organizations such as International Standard Organization (ISO), International Network for Bamboo and Rattan (INBAR) etc are coming up to promote bamboo houses in seismically active zone areas of developing countries. With research and construction of bamboo being initiated worldwide, use of indigenous materials like bamboo constitutes a large portion of housing in the world. Instead Quake-prone north-eastern India should switch to traditional forms of house-building, including houses made of bamboo and cane that are flexible and able to withstand tremors. The rationale behind holding the event in this region is to make the people aware of the advantages of low-cost bamboo based housing and also take into account the fact that this is seismically sensitive zone.

2 Bamboo Bamboo, the fastest-growing renewable natural building material, is much less expensive than steel. Out of 126 species of bamboos reported from India over 40 species are found in Manipur (Chauhan 1999). Species of bamboos are distributed abundantly in Manipur and most of these are economically important to the people of the state. Tests have proven that bamboo is a viable (if not better!) alternative for steel, concrete and masonry as an

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Fig. 2 Possibly the world’s largest bamboo structure

independent building material. It also possesses high residual strength to absorb shocks and impacts—highly suitable material for construction of houses to resist seismic and high wind forces. It is very efficient in sequestering carbon and contributes to the reduction of green house effect. It is believed that bamboo became the first option as a building material when people began to occupy area where bamboo grows naturally. The common reasons are its availability and ease of use. And later due to its lack of durability, most of people replaced the use of bamboo with other, more resistant material, such as wood and brick. Today, the durability of bamboo is no longer in question, since it was possible to find effective, low-cost preservatives and to develop simple and efficacious systems for its treatment. When used in building construction, one cardinal rule is to ensure that the bamboo is kept dry. This means that it should be kept free from splashing rainwater by a watertight foundation and by an overhanging roof. Correct design of all building details is a must; no chemical treatment will be good enough to solve the problems caused by incorrect design. In recent years, the demand for bamboo culms for the construction of houses has considerably increased. With the issue of sustainability the use of bamboo has regained a new value. Based on numerous past studies and field experiences dealing with bamboo construction and the ongoing development of bamboo utilization, it is widely recognized that bamboo construction can be found in a very wide variation. Bamboo can be used in all parts of the building, either as structural or architectural elements. In Colombia, architect Simon Velez has designed one of the world’s largest bamboo structures, a clubhouse (Fig. 2). In response to a devastating earthquake that killed 40,000 people in Iran, the UK Department of International Development conducted a study. The engineers were looking for cheap earthquake-proof housing to take the place of mud brick. They constructed a prototype Bamboo reinforced concrete house and used an earthquake simulator to find that the house stood sound during a 7.8 (Richter scale) earthquake. They found no cracking in the concrete, the Bamboo to be extremely resilient to earthquakes, and the cost to be split in half compared to mud-and-brick construction (Power 2004).

3 Physical and mechanical properties Most of the properties depend on the species, and the climatic conditions under which they grow (Sekhar and Gulati 1973). The density of bamboo is found to vary from 500 to 800 kg/m3 ,

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Bull Earthquake Eng Table 1 Mechanical properties of bamboo (Purwito 1995)

Properties

kg/cm2

Tensile strength

1,000–4,000

Compression strength

250–1,000

Bending strength

700–3,000

Modulus of elasticity

100,000–300,000

depending on the anatomical structure. Bamboo possesses high moisture content which is influenced by age, season of felling and species (Kumar et al. 1994). Because of the differences in anatomical structure and density, there is a large variation in tangential shrinkage from the interior to the outer-most portion of the wall (Sharma and Mehra 1970). This leads to drying defects, such as collapsing and splitting, and affects the behavior of bamboo during pressure treatment. One of the reasons for the rupture of bamboo is the presence of the vascular bundle (the water carriers) in the outer wall. As the bamboo dries and the bound water evaporates, the outer wall shrinks proportionally more than the inner, creating stress which, if it becomes great enough, will lead to wall rupture and crack. Water is held in bamboo in two ways: free water, which is held in the cell cavities, and bound water, which is held in the cell walls themselves. During storage, bamboo air-dries and loses free water until the moisture content is about 15 % at which point the bound water begins evaporating. Shrinkage doesn’t begin until bound water starts evaporating. Once the free water is gone bamboo begins shrinking in diameter as much as 10–16 % as well as in wall thickness (15–17 %). When heat-treated the bamboo will shrink as the remaining water is driven out, but within a week the bamboo will regain some moisture from the surrounding air’s relative humidity. Even after heat-treating, bamboo cells continue to lose and gain moisture, with corresponding dimensional changes, as the bamboo reaches equilibrium between the amount of bound water and the surrounding air’s relative humidity. Since dimensional variations only takes place during bound water gain/loss, any time the moisture content changes, its bore diameter and wall thickness also change. Bamboo possesses excellent strength properties, especially tensile strength. Table 1 gives the average value of the properties of bamboo. It is well known that the tensile strength of bamboo triples the compression strength and therefore, it will obviously be much larger than the buckling load of the culms. This takes tensile strength out of the critical path in relation to those properties that might be of interest for the structural and seismic engineers. Even then, the designer should bear in mind that in the case of trusses, some of the elements will have to sustain tensile forces. So, the strength mechanism of the culms under those forces should be analysed and understood. It is important that results of clear specimens are not directly transferred as those of full culms because, among other reasons, there will be a tendency of the culm to fail in the region of the nodes, the weakest link, and to develop high tensile parallel stresses, both factors being very much random in nature. Initial deformations of the culms would also lead to low rigidity at the beginning of the force deformation path. Although bending plays a major and significant role in certain applications, testing has shown that bending by itself is not a problem, since very rarely bamboo can, in an actual application, develop a condition where it will fail in bending. It is more likely that the failure would happen because of local buckling, longitudinal shear, local crushing under the loads, or a weak condition in the supporting areas. This means that effort by the designer should be concentrated on avoiding situations where these types of stresses can be critical. This is particularly important while dealing with joints (Arce 1990). One of the most critical is the area of connection design. In fact, joints play an extremely significant role in the behavior of bamboo structures, and this is another field where very little data is available.

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4 Design of base column foundation For base column foundation, there are numerous methods available to connect bamboo columns to concrete foundations, the three that are most prevalent are: the steel-pin connection, embedment of the bamboo into the concrete, and the grouted-bar connection. The steel-pin connection involves grouting a piece of reinforcing bar into the end of a culm and then placing the free end into a joint made of concrete. By leaving a small space between the end of the bamboo and the start of the concrete joint, a pinned connection—affected by only the reinforcing bar—is created due to the flexibility of the reinforcement. Such connections are well suited to space-truss structures although they have not been observed in ‘post-andbeam’ construction. The second type of connection is the embedment of the bamboo culms directly into a concrete plinth, foundation or grade beam. This type of connection has the advantage of producing a fixed end condition, which can be more desirable depending on the design. The disadvantages of this system are that a larger plinth is required and the bamboo has a tendency to rot at the connection interface. This system was employed in the Community Center at Camburi, Brazil. The grouted-bar connection involves steel reinforcing bars extending from the concrete foundation directly into the culms where they are grouted. The interface has the entire culm bearing upon the concrete.

5 Design of joint connection As to bamboo’s irregular dimensions the methods used by the different researchers and designers are often dependent on the bamboos which they choose and the techniques are also not so easy to be transferred from one to another. This limits the bamboo cane in the construction in a large dimension. Connection used for the ZERI pavilion at EXPO 2000 is mostly accepted by modern architect. To guaranteeing tensile strength, two different types of connections are used as shown in Fig. 3.

Fig. 3 Type A and Type B connection

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Type A-thread rods: For this connection the bamboo needs to be drilled. The thread rods are sticked into the holes. In these internodes, where the thread rods are in, the bamboo is filled with mortar. With the ends of the thread rods you can create different kinds of connections. For the connections it is important to use special dishes, also to fill the bamboo with mortar. Otherwise the bamboo would splitter, because of the force transmission at only one point. Type B-lateral steel flanges and bolts: This connection is similar to type A. The bamboo is drilled. The bolts are inserted into the bamboo in cross direction, the bamboo is filled with mortar. The connection itself is constructed by a lateral steel flange that is tied around the bamboo and joint with the shaded bolts. This connection transmits the forces to different parts of the bamboo and avoids the debit of only one point of the bamboo.

6 Design standard Experimentation and the implementation of bamboo as a structural material have led to a standardization and quantification of its capabilities, treatment and safety. International standards of bamboo are being investigated by the ISO. ISO (1999) provides the International Standard that applies to Bamboo structures based on their performance and on limit state design. This International Standard is only worried about the necessities for serviceability, mechanical resistance, and durability of structures. Bamboo used as composite makeup may require additional considerations beyond this Standard. The International Network for Bamboo and Rattan (INBAR 2005) with ISO published a model standard on structural design using bamboo (ISO 2004a) and a series of methods for determining the mechanical properties of bamboo (ISO 2004b,c). If the use of bamboo is limited to rural areas, the ISO standard established “experience from previous generations” as being an adequate basis for design. However, if bamboo is to realize its full potential as a sustainably obtained and utilized building material on an international scale, issues of the basis for design, prefabrication, industrialization, finance and insurance of building projects, and export and import of materials all require some degree of standardization (Janssen 2005). The National Building Code of India (NBCI 2005) addresses the use of bamboo in Part 6: Structural Design, Sect. 3—Timber and Bamboo: 3B Bamboo. The scope covers the use of bamboo for structures and provides requirements to satisfy acceptable performance. The NBCI additionally provides some examples of bamboo joints and connections, however the detailing (including dimensions and capacities) of such joints is not addressed. It must therefore be inferred that proof testing is required to qualify connection methods and joint types. Such an approach is obviously prohibitive when applied to residential construction. Furthermore, the NBCI refers to other Indian Standards (IS 6874:1973, 9096:1979, and 8242:1976) which refers to test methods and preservation of structural bamboo. The main difficulty in designing and constructing an engineered bamboo structure lies in the available standards which vary by country. Bamboo still has the stigma as “the poor man’s timber” and is not considered as a modern material. A building code would be the solution to this problem, and it would help formalize the position of bamboo. At present, no book or code of practice is available in India for design of bamboo structures on scientific lines. Since no comprehensive standard is available, it becomes hard to analyze the seismicity of bamboo structure in India. So there is a need to standardize a code for bamboo to implement bamboo structure in the seismic areas of India where bamboo is available in abundance.

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7 Preservation A study reported in INBAR (2002) considered the advantages and disadvantages of Bamboo used as a structural material. The advantages found in their study concluded to be areas of: ecological value, good mechanical properties, social and economic value, and energy consumption. They found disadvantages to be: preservation, fire risk, and natural growth. Low durability is the major drawback of bamboo in structural use. A problem that compounds the low natural durability of bamboo is its hollowness. The hollowness offers a relatively safe hiding place for the agents of destruction. In most tropical countries, the high relative humidity of the air adds to durability problems. A high moisture content in the bamboo—which makes complete drying difficult and thus provides an opening for fungal attack—poses uncertainties in its application in housing, furniture, etc. Several methods have been developed to remedy this. In many places, traditional preservation methods—such as curing, smoking, soaking and seasoning, and lime-washing—are used. Soaking bamboo in water is widely practised in Indonesia, Vietnam, Bangladesh and other countries (Sulthoni 1987). Chemical preservatives offer the best protection against termite and fungi. A comprehensive study on steeping, sap-displacement, diffusion, hot–cold bath and pressure processes has been conducted in India. The possible treatment techniques for bamboo have recently been summarized in numerous papers, for example: Liese (1980; 1997), Sulthoni (1987); Kumar et al. (1994). The performance of treated bamboos depends mainly on the location of use and the preservative employed. Bamboo treated with copper-chrome-arsenic (CCA) shows some decay after 15 years in exposed conditions. The performance in partially exposed or covered conditions is much better. A CCA-treated, low-cost bamboo house in India was found intact without any damage even after 40 years of service (Kumar et al. 1994). In Colombia, a bamboo house with ceiling and walls plastered with cement mortar is reported to have lasted more than 90 years (Hidalgo 1992). Preservatives can thus impart longevity to bamboo and thereby improve its performance in housing.

8 Structural analysis There are different techniques used for analyzing seismicity of the structure. The main technique currently used for this analysis is the linear modal time history analysis. All real physical structures, when subjected to loads or displacements, behave dynamically. The additional inertia force from, Newton’s second law, are equal to the mass times the acceleration. If the loads or displacements are applied very slowly then the inertia forces can be neglected and a static load analysis can be justified. Hence, dynamic analysis is a simple extension of static analysis. The force equilibrium of a multi-degree-of-freedom lumped mass system as a function of time can be expressed by the following relationship: F (t)i + F (t)d + F (t)s = F (t)

(1)

in which the force vectors at time t are F (t)i is a vector of inertia forces acting on the node masses F (t)d is a vector of viscous damping, or energy dissipation, forces F (t)s is a vector of internal forces carried by the structure F (t) is a vector of externally applied loads

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Equation (1) is based on physical laws and is valid for both linear and nonlinear systems if equilibrium is formulated with respect to the deformed geometry of the structure. For many structural systems, the approximation of linear structural behavior is made in order to convert the physical equilibrium statement, Eq. (1), to the following set of second-order, linear, differential equations: ◦

M¨u(t)a + Cu(t)a + K u (t)a = F (t)

(2)

in which M is the mass matrix, C is a viscous damping matrix (which is normally selected to approximate energy dissipation in the real structure) and K is the static stiffness matrix for ◦ the system of structural elements. The time-dependent vectors u (t)a , u (t)a and u¨ (t)a are the absolute node displacements, velocities and accelerations, respectively. For seismic loading, the external loading F(t) is equal to zero. The basic seismic motions are the three components of free-field ground displacements (u (t)ig ) that are known at some point below the foundation level of the structure. Therefore, we can write Eq. (2) in terms ◦ of the displacements u (t)a , velocities u (t)a and Accelerations u¨ (t)a that are relative to the three components of free-field ground displacements. Therefore, the absolute displacements, velocities and accelerations can be eliminated from Eq. (2) by writing the following simple equations: u (t)a = u (t)a + Ix u (t)xg + Iy u (t)yg + Iz u (t)zg

(a)

u (t)a = u (t)a + Ix u (t)a xg + Iy u (t)a yg + Iz u (t)a u (t)zg

(b)

u¨ (t)a = u¨ (t)a + Ix u¨ (t)a xg + Iy u¨ (t)a yg + Iz u¨ (t)a u (t)zg

(c)

◦

◦

◦

◦

◦

where Ii is a vector with ones in the “i” directional degrees-of-freedom and zero in all other positions. The substitution of the above three Eqs. (a), (b) and (c) into Eq. (2) allows the node point equilibrium equations to be rewritten as ◦

M¨u (t)a + Cu (t)a + K u (t)a = (−Mx u¨ (t)a xg − My u¨ (t)a yg − Mz u¨ (t)a zg ) The simplified form of Equation is possible since the rigid body velocities and displacements associated with the base motions cause no additional damping or structural forces to be developed. The Time History Response of a structure is simply the response (motion or force) of the structure evaluated as a function of time including inertial effects. A time dependent forcing function (earthquake accelerogram) is applied and the corresponding response—history of the structure during the earthquake is computed. That is, the moment and force diagrams at each of a series of prescribed intervals throughout the applied motion can be found. Computer programs have been written for both linear elastic and non-linear inelastic material behavior using step-by-step procedures. One such program is SAP2000 in which three–dimensional time history analyses can be carried out taking as input the three orthogonal accelerogram components from a given earthquake, and applying them simultaneously to the structure.

9 Modelling with SAP The models adopted for this study are asymmetric 2 storey bamboo and a RC frame building of dimension 8 m × 16 m in plan and 3m floor height. The structure is assumed to be situated in Manipur region. For the reinforced concrete frame system, the model dimension is taken same as the bamboo housing. The finite element analysis software SAP 2000 is utilized to

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create 3D model and run all analyses. The software is able to predict the geometric nonlinear behavior of space frames under static or dynamic loadings, taking into account both geometric nonlinearity and material inelasticity. The software accepts static loads (either forces or displacements) as well as dynamic (accelerations) actions. In the work, comparison of the performances of two types of structure using particular method of analysis available in the tool is attempted. Other features in respect of method of analyses would be tried in subsequent work and compared. As far as the theme of the paper present method of analysis was found to be useful. Bamboo properties are considered from available literature. Here numerical model helps in comparing the performances of the different types of structure. Randomness of material properties of civil engineering structures is common and its effect on performance in real situation is also well known. FEM model helps to some extent but further experimental studies are required. 10 Bamboo housing model In geometry, bamboo is essentially a hollow cylinder with periodic stiffeners located at nodes. The internal and external diameters of the cell modeled in this study are 70 mm and 100 mm, respectively. Cell wall thickness is 15 mm. The properties of the bamboo structural modeled are having density 7.3575 kN/m3 , modulus of elasticity 20,000,000 kN/m2 , Poisson ratio 0.3 and damping ratio is 0.0152. For simplifications, all members are modeled as single member even they might consist of two or more bars on design level. All foundations are assigned as hinge. As different types of connection between frames of beam and columns are adopted by different countries, in this work a simple connection of bamboo is assumed to be assigned between beams and columns. Figure 4 shows a model of a 2 storey bamboo housing system. Live loads on floor are taken as 2.00 kN/m2 . Earthquake load was analyzed as response spectrums. Dead load is self weight of structures. Self weight of member, which is bamboo bars, is automatically involved by SAP 2000 on the calculations. Dead load for floor is assumed to be 0.50 kN/m2 and supported by beams at the edge of covering are as continues/uniform load. Dead loads for roof are determined as point load as the result of transformation of uniform load 0.15 kN/m2 placed at defined joints. In accordance with IS 875 part 2, an imposed load of 0.75 kN/m2 has been considered for the roof.

Fig. 4 2-storey bamboo housing model

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Table 2 Characteristics of the different earthquake motions Earthquake

Magnitude

Station

Record/component

PGA (g)

El-Centro earthquake 1940/05/18

7

117 El Centro Array #9

IMPVALL/I-ELC-UP

0.205

IMPVALL/I-ELC180

0.313

IMPVALL/I-ELC270

0.215

KOBE/KAK-UP

0.158

KOBE/KAK000

0.251

KOBE/KAK090

0.345

Kobe earthquake 1995/01/16

6.9

Kakogawa

Nishi-Akashi

Table 3 Frequency of different housing systems from the time history analysis

Housing systems

Bamboo housing model RC frame model

KOBE/NIS-UP

0.371

KOBE/NIS090

0.503

KOBE/NIS000

0.509

Mode

Period (sec)

Frequency (cyc/sec)

1

1.20643

0.82889

2

0.398507

2.5094

1

0.428698

2.3326

2

0.139544

7.1662

11 RC frame model For the comparison with the bamboo housing model, the same dimension is taken for modeling RC frame (Fig. 5). The size of the beams and columns are taken as 250 mm × 300 mm and 300×300mm resp. The loads on the structure are as per IS 875 Part 2 1987.

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Bull Earthquake Eng Table 4 Peak roof displacement (in m) of the building as obtained from time history analysis in SAP Housing system

El-Centro earthquake

Kobe earthquake Kakogawa closest to fault rupture 26.4 km

Nishi-Akashi closest to fault rupture 11.1 km

Bamboo housing model

0.1723

0.0854

0.06559

RC frame model

0.02795

0.01679

0.0994

Table 5 Base shear (in kN) of the building in x- direction in SAP Housing system

Bamboo housing model RC frame model

El-Centro earthquake

248.1 1127

Kobe earthquake Kakogawa closest to fault rupture 26.4 km

Nishi-Akashi closest to fault rupture 11.1 km

140.8 716.1

185.8 3047

12 Analysis Modal Time History analysis has been carried out using the Imperial Valley Earthquake record of May 18, 1940 also known as the El-Centro Earthquake at Station: 117 El Centro Array #9 closest to fault rupture 8.3 km and Kobe Earthquake of January 16, 1995 at two different stations viz. Kakogawa closest to fault rupture 26.4 km and Nishi-Akashi closest to fault rupture 11.1 km for obtaining the various floor responses. Peak ground acceleration of the different types of Earthquake for the vertical, east west and north south direction are shown in Table 2.

13 Result The natural frequencies of the different housing system are shown in Table 3. Figures 6 and 7 shows displacement time history of top floor (shorter direction) for bamboo housing model and RC frame building respectively. Base shear time history (shorter direction) for bamboo housing model and RC frame building are shown in Figs. 8 and 9 respectively (Tables 4, 5). From the frequencies of the different housing system the time period, response reduction factor, zone factor, and importance factor can be work out from the IS 1893–2002. From the time period, Sa/g (Average response acceleration coefficient) can be derived from as per the IS-1893–2002 for 5 % damping. For the different construction material used in housing the correction factor is multiplied as per IS-1893–2002. The damping ratio of different housing system is shown in Table 6. From the model of different structural systems, the seismic mass of the system is worked out and for determining the seismic force static co-efficient method is used (Table 7).

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El-Centro Earthquake May 18, 1940

Kobe Earthquake of January 16, 1995 at Kakogawa closest to fault rupture 26.4km

Kobe Earthquake of January 16, 1995 at Nishi-Akashi closest to fault rupture 11.1km Fig. 6 Displacement time history of top floor (shorter direction) for bamboo housing model

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El-Centro Earthquake May 18, 1940

Kobe Earthquake of January 16, 1995 at Kakogawa closest to fault rupture 26.4km

Kobe Earthquake of January 16, 1995 at Nishi-Akashi closest to fault rupture 11.1km Fig. 7 Displacement time history of top floor (shorter direction) for RC frame model

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El-Centro Earthquake May 18, 1940

Kobe Earthquake of January 16, 1995 at Kakogawa closest to fault rupture 26.4km

Kobe Earthquake of January 16, 1995 at Nishi-Akashi closest to fault rupture 11.1km Fig. 8 Base shear time history (shorter direction) for bamboo housing model

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El-Centro Earthquake May 18, 1940

Kobe Earthquake of January 16, 1995 at Kakogawa closest to fault rupture 26.4km

Kobe Earthquake of January 16, 1995 at Nishi-Akashi closest to fault rupture 11.1km Fig. 9 Base shear time history (shorter direction) for RC frame model

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Bull Earthquake Eng Table 6 Corrected Sa/g as per IS 1893–2002 (for medium soil) Housing system

Bamboo housing model RC frame model

Table 7 Seismic force on different housing system

Sa/g (5 % damping) IS 1893–2002 1st mode

2nd mode

1.127 2.5

2.5 2.5

Damping ratio offered by in System (%)

1.523 7

Housing system

Bamboo housing model

1st mode

2nd mode

2.0621 2.25

4.57325 2.25

Seismic force on different housing system (kN) 1st mode

RC frame model

Corrected Sa/g as per System

2nd mode

21.7

48.3

302.6

302.6

14 Conclusion Based on the information collected on bamboo, it is clear that bamboo may be a suitable substitute for a range of materials especially in developing countries where buildings materials are expensive and/or rarely available. Bamboo may have advantages and drawbacks which must be carefully weighed. Some of the positive aspects such as lightweight design, better flexibility, and toughness due to its thin walls with discretely distributed nodes and its great tensile strength make it a good construction material and a perfect material for earthquakes. As stated earlier, joints play a significant role in the behavior of bamboo structures: the building of structurally efficient, more durable and possibly larger and more economical bamboo structures will depend to a large extent on improvements and developments in jointing technology. In fact, it is the duty of the designer to make best of the material. In this paper, dynamic analysis with El-Centro Earthquake and Kobe Earthquake excitation data as input are carried out on bamboo structure and RC frame structure models to observe the behavior of the structure under earthquake excitation. In most of the numerical studies available in literature, researchers consider different features of ground motion by choosing different types of ground motion, here also an attempt has been made in that respect. The accelerogram components for these two earthquakes are taken from the Pacific Earthquake Engineering Research (PEER) Strong Ground Motion database where the data are provided as a discrete series of readings which is then uploaded to SAP 2000. From the result, the analysis that applies to the bamboo house model produces forces and frequencies smaller than RC frame model. Discussion about displacement comparison we can see clearly from the graph where displacement for bamboo structural model is very high. This is due to the flexibility of the bamboo. Although the peak roof displacement is high in bamboo structural model, the base shear of the RC frame model is larger than the bamboo structural model, indicating better performance of the bamboo structural model than RC frame model. And also even though, the number of the main vertical member of the bamboo structure is more than that of RC frame structure, for the same floor area, the weight of the material required for construction of bamboo structure is less. The result clearly proves that bamboo has adequate mechanical strength and is an efficient earthquake-resistant building material. The result in

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comparative scale has been referred for these two types of structure only and it is useful from the theme point of view of the paper. The primary goals of using bamboo is that it is a more sustainable product than reinforced concrete, and due to its lighter weight, it is far less prone to cause/experience a fatal collapse in an earthquake. Thus it can be concluded that bamboo can be the material of choice for construction in seismic zone area especially in Manipur where bamboo is easily and abundantly available.

References Amada S, Lakes RS (1997) Visco elastic properties of bamboo. J Mater Sci 32:2693–2697 Arce OA (1990) Bamboo in construction: new ways in building construction. Paper presented at an interuniversity research seminar. University of Technology, Wroclaw, Poland Cane and Bamboo Technology Centre (2001) Affordable bamboo housing in earthquake prone areas: an international workshop organised. Government of Mizoram, International network for bamboo and rattan, Aizawl, Mizoram, India Chauhan AS (1999) Manipur. In: Floristic Diversity vol. 3. Botanical Survey of India, p 1149–1153. Kolkata, India DeBoer D, Bareis K (2000) Bamboo building and culture—the architecture of Simon Velez, architect. Bogota, Colombia Ghavami K (2007) Bamboo: low cost and energy saving construction materials. In: Proceedings International Conference on Modern Bamboo Structures, 28–30 October, pp 5–21. Changsha, China Hidalgo AO (1992) Technologies developed in Colombia in the bamboo housing construction field IS 875 Part 2 (1987) Code of practice for design loads for buildings and structures, imposed loads. Bureau of Indian Standards IS: 1893–2002, Criteria for earthquake resistance and construction of buildings. Bureau of Indian standards, New Delhi International Network for Bamboo and Rattan (INBAR) (2002) Bamboo structure at CO: advantages and disadvantages. http://www.bwk.tue.nl/bko/research/Bamboo/bamboo.htm. Accessed 6 June 2005 International Network for Bamboo and Rattan (INBAR) (2005) Bamboo in construction: an Introduction International Standard Organization (ISO) (1999) Bamboo structural design International Standards Organization (ISO) (2004a) ISO 22156, Bamboo-structural design International Standards Organization (ISO) (2004b) ISO 22157–1, Bamboo-determination of physical and mechanical properties—Part 1: requirements International Standards Organization (ISO) (2004c) ISO 22157–2, Bamboo-determination of physical and mechanical properties—Part 2: laboratory manual Inoue M, Nakhara M, et al. (2004) Development of connecting method for natural round bamboo. In: Proceedings for the World Conference on Timber, Engineering, p 331 Janssen J (1981) Bamboo in building structures. Eindhoven University of Technology, Netherlands, Doctoral Thesis Janssen JJA (2000) Designing and building with bamboo. INBAR Technical Report No.20. International Network for Bamboo and Rattan, Beijing, China. 207 pp Janssen JA (2005) International standards for bamboo as a structural material. Struct Eng Int 15(1):48–49 Kumar S, Shukla KS, Dev I, Dobriyal PB (1994) Bamboo preservation techniques: a review. INBAR Technical Report No. 3. International Network for Bamboo and Rattan, New Delhi, India. 59 pp Liese W (1980) Preservatives of bamboo. In: Lessard G, Chouinard A (eds) Bamboo research in Asia. In: Proceedings of a workshop held in Singapore, 28–30 May 1980. International Development Research Centre, Ottawa, Canada, pp 165–172 Liese W (1997) The protection of bamboo against deterioration. In Jena PK (ed) Proceedings 2nd international conference on non-conventional building materials, Bhubaneswar, India, 17–19 June 1997. Natural Resource Development Foundation, Bhubaneswar, pp 111–117 Masani (1977) Studies on bamboo concrete composite construction Maulik DK, Sanghvi CS (2011) Comparative study of bamboo (ikra) housing system with modern construction practices. National Conference on Recent Trends in Engineering & Technology Mitch DR (2010) Structural behavior of grouted-bar bamboo column bases. University of Pittsburgh, Master’s Thesis National Building Code of India (2005) Part 6 Structural Design—Section 3 Timber and Bamboo: 3B Bamboo

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Bull Earthquake Eng Paudel SK (2008) Engineered bamboo as building material in modern bamboo structures. In: Xiao Y, Inoue M, Paudel SK (eds), Proceedings of 1st international conference on modern bamboo structures (ICBS-2007), Changsha, China, October 28–30, 2007 Power M (2004) Bamboo cures earthquakes. Discovery Magazine Purwito (1995) The application of Bamboo for earthquake–resistant Houses, Bamboo, people and the environment. In: Proceedings of the 5th International Bamboo Workshop and the IV International Bamboo Congress Ubud, Bali, Indonesia l9–22 June 1995, vol 3, Engineering and Utilization, p 67 Sekhar AC, Gulati AS (1973) A note on the physical and mechanical properties Dendrocalamus strictus from different localities. Van Vigyan 11(314):17–22 Sharma SN, Mehra MI (1970) Variation of specific gravity and tangential shrinkage in the wall thickness of bamboo and its possible influence on trend of the shrinkagemoisture content characteristics. Indian For Bull 259:7 Sulthoni A (1987) Traditional preservation of bamboo in Java, Indonesia. In: Rao AN, Dhanarajan G, Sastry CB (eds), Recent research on Bamboo. Proceedings of ‘the International Bamboo Workshop, Hangzhou, China, 6–14 October 1985. Chinese Academy of Forestry, Beijing, China, International Development Research Centre, Ottawa, Canada. pp 349–357 Shyamasundar K, Vengal J (2006) Promotion of bamboo housing system and recent developments. IPIRTITRADA, Research report Silva ECN, Walters MC, Paulino GH (2006) Modeling bamboo as a functionally graded material: lessons for the analysis of affordable materials. J Mater Sci 42:6991–7004

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