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“...Construction and Building Materials 174 (2018) 701-712
ELSEVIER
Contents lists available at ScienceDirect
Construction and Building Materials
journal homepage: www.elsevier.com/locate/conbuildmat
Construction and Building
MATERIALS
■ ■
Mechanical behaviour of different type of shear band connections being used in reconstruction housing in Nepal L™
Santosh Yadav3, Yannick Sieffert3'* *, Eugenie Crete5, Florent Vieux-Champagnec, Philippe Gamier5
a Universite Grenoble Alpes, Grenoble INP, CNRS, 3SR, F-38000 Grenoble, France
bLaboratoire CRAterre, Unite de recherche AECC, £cole Nationale Superieure d’Architecture de Grenoble, Grenoble, France
cLMDC, Institut National Des Sciences Appliquees de Toulouse, Toulouse, France
HIGHLIGHTS
• The use of shear bands in masonry structures.
• Experimental approach to determine the mechanical behaviour of different materials used as shear bands.
• Reconstruction housing in Nepal.
ARTICLE INFO
ABSTRACT
Article history:
Received 10 November 2017 Received in...”
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“...but the extent of damage varies. The reason behind this variation is the respect of seismic safety rules during the construction works and the building lifespan, on the one hand, and people’s understanding of the building behaviour and their respect of the safety measures during seismic activity, on the other hand. When local seismic activity is important, inhabitants and local professionals usually developed “local seismic cultures” over time [8]. Hence, in order to develop seismic strategies that cope with local conditions, studying historical buildings and traditional construction practices, the material used, and the cultural values related to it is of high importance. These specific building cultures are being lost with the import of international standards, which are not always relevant in the context of the country and often not sustainable. Decontextualized guidelines usually do not cope with local financial and professional capacities and resulting low quality works [8]. Hence, i...”
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“...and INGOs have started training masons on properly implementing shear bands. Fig. 2c) shows the use of concrete and timber shear bands in stone masonry structures with clay mortar in Megapauwa, Dolakha district, and in Fig. 2d), a concrete shear band can be seen in a stone masonry with cement mortar building in Kavrepalanchok district.
2.2. Design catalogue for reconstruction
The National Building Code regarding masonry and RC structures was published in 1994. It recommends the use of horizontal
Fig- 2. a) Use of stone as a shear band, b) Timber shear band in brick masonry, c) Use of concrete and timber shear band in clay mortar masonry and d) Concrete shear band in cement mortar masonry building....”
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bands/ring beams at plinth, lintel, roof, and gable level as a structural reinforcement. But this practice was far too often not implemented due to lack of knowledge among local community and authority [23].
The design catalogue for earthquake resistance guidelines consists of the design specification for simple masonry building with minimum requirements that should be fulfilled for reconstructing buildings that could resist the damage caused by the earthquake in the near future using horizontal shear bands as shown in Fig. 3. The main objective of reconstruction housing guidelines is to translate into a concept of safer settlement using the principles of Build Back Better (BBB) [7]. This design catalogue was prepared to have more efficient approach for reconstruction work with the model design building with one or two storeys. The first design catalogue for reconstruction work has been prepared in a more conservative...”
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“...Fig. 7. The rate of displacement was 0.4 mm/s for each of the test.
3.3. Test setup and data acquisition
To take into account the pre-compressive load acting at shear band section due to wall above that level along with live load and loading from the roof, the total load has been calculated taking the density of masonry 20.4 kN/m3 and imposed live load of 3 kN/ m2 and 0.75 kN/m2 for sloping roof member with purlins [4].
Considering height above sill band 2 m for single storey building and 4.55 m for two-storey building, the maximum vertical load, acting at the shear band level has been computed as 15.2 kN and 33.36 kN respectively. To apply this pre-compression loading on the wall, a metallic plate was used on both sides of the sample with six bolts having 12 mm diameter. Each bolt was pre-compressed using 20 Nm torque wrench. The pre-compressive force in the bolt comes out to be 8.33 kN. With this experiment, the sliding behaviour of the shear band at the interface layer has been observed...”
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10.00
io.oqJ
SECTION A-A
Fig. 6. Experimental set up for cyclic shear loading.
of each range of displacement cycle was started from negative loading. The two curves for same type of shear band have similar pattern of loading and displacement thus, the reproducibility of the sample was met up to some extent however a number of specimens is required to be tested for calculation of a mean and standard deviation. Likewise, the result for Timber SB2_1 is only up to 16 mm which is due to the problem that the loading plate was about to touch the metallic plate of experimental setup while performing the test and the test was stopped beyond that limit.
For proper bonding between concrete and clay mortar layer, few pieces of stone were used while placing concrete. As shown in the Fig. 11, there is sliding behaviour observed both in positive and negative loading zone around 10 kN force which means at this level of loading...”
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Fig. 7. Displacement controlled loading pattern.
were not exactly the same in two specimens with concrete SB. The nature of hysteresis loop which is wide resulting in more dissipation of energy can be observed in the plot. Also, in the case of bamboo shear (Fig. 12), the hysteresis loop is thinner and comparable in both the specimen addressing the reproducibility requirement for validation of test method and results obtained.
While making a comparison between timber shear band type 1 and 2 as shown in Fig. 13, SB type 1 has narrow hysteresis loop as compared to type 2. The reason could be due to the connection of transverse ties using a nail in the case of type 1 which is easily bent and shifted with loading. Similarly, the curve with type 1 is symmetric which could be due to the equal force needed for bending of the nail connection (Fig. 14) in both direction allowing similar displacement whereas with type 2, the...”
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Fig. 10. Hysteresis curve for timber shear band type 2.
timber is lower than in concrete and so is the nature for dissipation of energy. The reason for concrete shear band dissipating more energy could be the more surface area is in contact with the clay layer creating a more frictional loss of energy. In case of bamboo, there is sudden sliding behaviour observed at low shearing load and the hysteresis loop is also thinner as compared to timber shear band as shown in Fig. 16.
4.2. Dissipation of energy
One of the use of shear band is to limit the propagation of a crack in the wall, confine all the wall together and dissipate energy by sliding friction caused during seismic action. For this purpose, the amount of energy dissipated by each cycle upon particular displacement was measured from the previous hysteresis loop curve using OriginPro 2017 software (http://www.originlab.com/2017) and taking the average between...”
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“...using different material.
4.4. Cost aspect
In order to conduct a financial analysis of construction works of similar types of building in different affected districts of Nepal, a model with two and a half storey houses - which includes an attic that is used as a storage place - was chosen with mud mortar as guided in the Nepal National Building Code 203 and the dimension of the building was taken from the design catalogue developed by DUDBC. The detailed quantity of work and a bill of quantities were calculated to get the total cost of construction. The cost of construction ranges from € 17,000 up to € 22,000 (to compare with the state subsidies of € T1T1\ From the field construction work carried out by CRAterre in Dhading district, the cost for reconstruction was approximately € 15,000 with timber shear bands which corresponds with the theoretical cost estimation. The design catalogue for reconstruction and NBC has provision of using shear band using timber, concrete and bamboo, so the cost...”
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. 15. Hysteresis curve comparison of concrete SB with timber SBl_2_dry.
Force (in kN) 3 Force (in kN)
- Bamboo SB 1
- Timber SB 1-2
0 Hysteresis curve comparison
25
20
15
10
5
0
-5
-10
-15
-20
-25
-30
-25 -20 -15 -10 -5 0 5 10 15 20 25
Displacement (in mm)
Fig. 16. Hysteresis curve comparison of bamboo SB with timber SBl_2_dry.
5. Conclusion and recommendation
5.3. Conclusions
(1) Most of the masonry houses built in rural part of Nepal did not have seismic shear band even though it was already mentioned in the national building code of Nepal which highlights the lack of proper education and implementation of law resulting in huge damage of life and property during Gorkha Earthquake 2015. People started reconstruction works by themselves by implementing seismic shear bands, but due to lack of proper supervision by a trained person, they are not always able to make the shear band correctly.
(2) Regarding the shear...”
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Table 2
Effective stiffness against sliding, energy dissipated.
S. No. Name of specimens Elastic Effective Stiffness, k (N/m) Energy dissipated
Force, kN Displacement, mm Elastic, l
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References
[1] A.S. Arya, T. Boen, Y. Ishiyama, Guidelines for Earthquake Resistant Non-Engineered Construction, UNESCO, Paris, France, 2013.
[2] J. Bothara, S. Brzev, A Tutorial: Improving the Seismic Performance of Stone Masonry Buildings, 2011.
[3] Bureau of Indian Standard, IS 1893-1984 Criteria for Earthquake Resistant Design of Structures, 2405 §, 1986, India.
[4] Bureau of Indian Standard, Code of Practice for Design Loads (Other Than Earthquake) for Buildings and Structures, 875 BIS §, 1989, India.
[5] Bureau of Indian Standard. Recommended Guidelines for Concrete Mix Design, 1999, India.
[6] T. Choudhury, G. Milani, H.B. Kaushik, Comprehensive numerical approaches for the design and safety assessment of masonry buildings retrofitted with steel bands in developing countries: the case of India, Constr. Build. Mater. 85 (2015)227-246, https://doi.Org/10.1016/j.conbuildmat.2015.02.082.
[7] DUDBC, Design Catalogue...”
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