A Comparative Study of Retrofitting Of R.C. Building Using Steel Bracing And Infill Walls

Prof. Pravin B. Waghmare
Acharya Shrimannarayan Polytechnic Pipri (M)- Wardha-Maharashtra

The objective of this study is to identify an efficient retrofitting method for existing open ground story reinforced concrete frame buildings. Failure of several soft-stored buildings in the past earthquakes underscores the need to retrofit existing soft-story buildings. A common cause for the collapse of multi-storied buildings is the occurrence of soft story in the ground floor due to the presence of infill walls in the upper story. During the Bhuj (Gujarat) earthquake of 6thJanuary 2001 several soft storied building failed there by confirming the vulnerability of such buildings to earthquake loading. This underscores the need to retrofit existing soft story buildings to prevent their total collapse. The existing building structures, which were designed and constructed according to early codal provisions, do not satisfy requirements of current seismic code and design practices. A two dimensional R.C. frame designed with linear elastic dynamic analysis using response spectrum method. The computer software package STAAD Pro–2005 is used for dynamics analysis technique is used to assess the performance of a (G + 4) reinforced concrete buildings, of which the ground storey is a parking facility the ground storey is 3.5m high while the upper stories giving a total height of 15.5 m. the building is located in Seismic Zone IV.

The RC frame is retrofitted by three methods namely,
1) Brick masonry infill in the ground story.

2) Steel braces in the ground story.

3) R.C. Structural wall in the ground story.

The study concludes that the building designed as per provisions of IS: 456:2000 using limit state method of design, and analyzed as per existing seismic code IS: 1893-2000 of all these three methods studied the use of structural wall in the ground story panel gave the maximum strength and ductility.

Keywords: Open ground storey, brick infill, RC wall Infill and Steel Bracing.
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A Comparison of Marshall Properties of Various Types Of Cold Mixes Found In Nigeria

1. Futminna
2. Unilorin

This study present, the Marshall properties of the cold mix asphalt produced with the DPWS modified bitumen were compared with those of the commercial cold mixes in use in Nigeria. The following Stability and flow result were obtained after careful laboratory experiment; for the DPWS modified cold mix Asphalt a stability of 5.8KN and flow of 4mm were obtained when using the normal hot mix method of testing, while stability of 9.58KN and flow of 4.5mm were obtained when air dried method was used. The Portland Emco shows stability of 2.21KN and flow of 3.95mm when it was subjected to test using the normal hot mix method of testing, while a stability of 4.37KN and a flow of 4.85mm were obtained air dried method was used. The Carboncor shows stability of 4.27KN and flow of 5.5mm when it was subjected to test using the normal hot mix method of testing, while a stability of 9.79KN and a flow of 5.5mm were obtained when air dried method was used. The UPM could not be tested for stability when it was subjected to test using the normal hot mix method of testing, but using the air dried method a stability of 1KN and a flow of 6.85mm were obtained. This shows that the modified cold Asphalt has a good strength when subjected to worst condition.

Keywords: Marshall Properties, Stability, DPWS, Cold Asphalt
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Evaluation Of Effectiveness Of Strawbale As A Building Material

Fawale, Babatunde Lawale
Ajayi, Johnson Oluwafemi
Oyedemi, Peter Oluwatosin

This project is an evaluation of the effectiveness of strawbale in building construction. It introduced the use of straw, which when baled could be used as a resource, that is, as a walling material, more economically than other conventional walling materials.

This study shows the edges that strawbale has over other conventional walling materials (sandcrete block), thermal insulating property, availability ease of construction, economical amongst others. The minimum plaster thickness (coating) which when applied to the strawbale wall that can give the optimum strength was found to be 15mm this is obtained from compressive strength test.

It also displays the graphical representation of the thermal insulation tests carried out on the two prototype buildings (strawbale and sandcrete block), in which strawbale building retained more heat than the sandcrete block building.
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Study The Contribution In The Additions Mineral On The Paste, Mortar And Their Impact On Total Porsity

Guimer Tarek and Mellas Mekki
Department of Civil Engineering, Mohamed Khider University, Biskra, BP 145, Biskra 07000, Algeria
Tel fax: 033 73 45 28

This work aims to study the evolution of the resistance of Portland cement pastes and mortars containing two mineral additions such as calcareous filler and finely crushed slag.

The effects of the addition of two mineral additions to Portland cement pastes are mortars, has been carried to evaluate the evolution of the mechanical resistance as function of the age and the mode of the treatment .This study is a simplified approach to show the contribution of the mineral addition on the development of the mechanical resistance, and the porosity obtained using methanol exchange method. In addition, to confirm this study and based on laboratory test resorts approximate equations were obtained

Keywords: Porosities, cement paste, mortar, mechanical resistance, exchange by methanol.
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Socio Economic Impact Of Failure Of Transmission Line Tower Foundations

A report by Christian Johnson and Thirugnanam

Transmission line towers are constructed for power evacuation purpose from generating stations to various load centers. Though they are considered to be the most stable and versatile semi-permanent structure, often they collapse due to failure of foundations, disrupting transfer of large blocks of power affecting the society to a larger extent. A brief review of literature on failure of transmission line tower foundations have been made and Case study involving data collection and visual inspection of transmission line tower foundation apart from diagnosis of transmission line tower stubs and laboratory experimentations have been presented. Based on the literature review and the case study undertaken as a part of the research, three predominant causes leading to failure of transmission line tower foundations have been discussed. Socio – economic impact of failure of transmission line tower foundations have been discussed. Remedial measures found through the research study for preventing failure of transmission line tower foundations have been briefly outlined.

Corrosion, Foundations, Failure, socio- economic, transmission line tower
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