Rubble-stone masonry structures are found abundantly in the Asian countries along the Himalayan range. Such structures are usually constructed in dry-stone masonry or are constructed in mud mortar, which makes them susceptible to damage and collapse in earthquakes. In order to study the seismic behavior of these structures, dynamic shake table tests on three reduced-scale rubble-stone masonry models were conducted. The models comprised a representative school building, a residential building, and a model incorporating simple cost-effective features in the form of horizontal and vertical reinforced concrete elements. This paper presents the results of shake table tests carried out on rubble-stone masonry buildings including: damage pattern, capacity curves, damage limit states, and response modification factors of these structures. Test data indicates that seismic performance of rubble-stone masonry structures can be significantly improved by incorporating cost-effective features such as vertical members and relatively thin horizontal bands.
Bamboo is a naturally available, fast growing and renewable resource. Bamboo plants are found all over the world in tropical and non-tropical regions. Asia pacific region is specifically rich in bamboo biodiversity. Due to high energy demand of existing construction materials and scarcity of other naturally available materials like wood, bamboo is a good alternative for construction. This paper reviews the mechanical properties and use of bamboo in construction. The tensile strength of different bamboo species varies in the range 70-210 MPa, compressive strength 20-65 MPa, elastic modulus 2500-17500 MPa, and modulus of rupture 50-200 MPa. Bamboo is a versatile material and can be used in construction in various ways. Bamboo can be engineered to specific need in construction such as laminated and scrimber bamboo. Engineered bamboo are used for various housing purposes such as roofing and flooring. Bamboo culms are often used directly without any alteration as structural members such as beams and columns. Bamboo can also be used as reinforcement in concrete as a replacement to steel. The shear and flexural behavior of bamboo reinforced concrete (BRC) beams is significantly better than plain concrete beams. Bamboo fibers reinforced concrete (BFRC) is a good alternative to existing synthetic fibers reinforced concrete such as glass and steel fibers. Development of standardized testing procedures and structural specifications utilizing existing and future research findings will pave the way towards an extensive use of bamboo in construction industry.
This paper presents the outcome of a research study aimed at the performance evaluation of rice husk ash as partial replacement of cement in sandcrete blocks used as masonry units. Rice husk from the rice cultivated in the North of Pakistan was used in the study. It was first combusted in a locally manufactured incinerator to convert it into rice husk ash (RHA) and then finely ground to powder form for use with cement. Blocks with the size of 305×203×152 mm were molded with 0, 10, 30, 40 and 50% replacement of cement with RHA to find compressive strength at 3, 7, 14 and 28 days age of curing. The results showed that water requirement for the required workability of the sandcrete increased along with the RHA content, whereas the compressive strength decreased with increase in RHA content. However, the comparison of compressive strengths of RHA sandcrete blocks with the strength of commercial concrete blocks available in the market and used as masonry units in Pakistan showed that sandcrete blocks having the sand to binder ratio of 1:8 and using up to 40% of RHA as replacement of cement gave larger compressive strength than that of commercial concrete blocks and only marginally lower strength for 50% replacement.
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