NISCAIR Online Periodicals Repository Collection: IJEMS Vol.14(3) [June 2007]

Evaluation of Turkish seismic code for mass irregular buildings

Tue, 29 May 2007 22:58:59 GMT

Title: Evaluation of Turkish seismic code for mass irregular buildings

Authors: Aydin, Kamil

Abstract: Several earthquake-prone countries including Turkey do not consider vertical mass discontinuity as a type of structural irregularity in their seismic codes. However, other earthquake prone countries clearly explain the mass irregularity and have limitations on the use of approximate methods to determine the earthquake forces developed in an irregular structure. The applicability of equivalent lateral force procedure of the Turkish earthquake code for mass irregular buildings is examined in this study. This is achieved by comparing the approximate results to those obtained by linear and non-linear time history analyses. 75 real and 100 simulated earthquake records are used in time history analyses. Two-dimensional 5, 10, and 20-story structures idealized as shear and frame buildings are studied. Mass irregularity is resulted from varying the mass of one floor and keeping the other story masses constant. Effect of altering the mass of different floors is also investigated. The comparison of the analysis results shows that the approximate method always overestimates the linear behaviour regardless of structure height, building rigidity and degree of mass irregularity. The method, however, underestimates the non-linear response of story columns. In light of the results obtained in this study, the inclusion of mass irregularity to the code appears appropriate.

Page(s): 220-234

Strength prediction of silica fume concrete by accelerated warm-water curing method

Tue, 29 May 2007 22:58:59 GMT

Title: Strength prediction of silica fume concrete by accelerated warm-water curing method

Authors: Atiş, Cengiz Duran

Abstract: In this paper, the results of a laboratory work predicting the compressive strength of silica fume (SF) concrete by accelerated warm-water curing method (WWM) have been presented. A parametric study has been carried out by producing a total of 48 concrete mixtures with three different cement dosages (350 kg/m³, 400 kg/m3, 450 kg/m3), four different water-cement ratios (0.3, 0.4, 0.5, 0.6) and four SF replacement ratios with cement (0%, 10%, 15%, 20%) on mass basis. Control normal Portland cement (NPC) concrete and SF concrete are cured with accelerated WWM in accordance with ASTM and Turkish standards. The linear relations have been established between accelerated WWM compressive strength and 28-day compressive strength for NPC concrete and SF concrete, separately. Although, the inclusion of SF influences the parameter of prediction equation when compared to NPC concrete, the analyses of the results indicate that prediction of SF concrete compressive strength by accelerated warm-water curing is possible with correlation coefficient (R²) higher than 90%.

Page(s): 266-270

Chloride resisting concrete containing rice husk ash and bagasse ash

Tue, 29 May 2007 22:58:59 GMT

Title: Chloride resisting concrete containing rice husk ash and bagasse ash

Authors: Ganesan, K; Rajagopal, K; Thangavel, K

Abstract: In this paper, the effects of rice husk ash (RHA) and bagasse ash (BA) as cement replacement materials on the chloride resisting properties, important to durability of concrete structures have been studied. RHA and BA have been used up to 30% replacement by weight of cement with fixed water to binder ratio of 0.55. The properties of concrete investigated include water absorption, permeability, sorptivity, resistance to chloride ion penetration in terms of total charge passed in coulombs and chloride diffusion coefficient. The compressive strength of concretes containing RHA and BA were also supplemented. The specimens incorporating RHA or BA, when exposed to chloride solution exhibit significantly lower charge passed value and lesser chloride diffusion for all cement replacement levels (CRL). Overall results indicate that RHA (25-30% CRL) and BA (15-20% CRL) blended concretes showed superior durability properties.

Page(s): 257-265

Rutherford back scattering and optical band gap of In/Sb thin films

Tue, 29 May 2007 22:58:59 GMT

Title: Rutherford back scattering and optical band gap of In/Sb thin films

Authors: Mangal, R K; Vijay, Y K; Avasthi, D K; Shekhar, B R

Abstract: Thin films having constant thickness of indium over varying thickness of antimony are deposited on glass substrates using vacuum evaporation method. Films are irradiated by Ag¹²⁺ heavy ions of energy 160 MeV at the fluence 2.2×10¹³ ons/cm². The optical absorption spectra have been recorded at room temperature of as-deposited and Ag¹²⁺ ion beam irradiated samples which show mixing of In/Sb bilayer. Rutherford back scattering (RBS) spectra also carried out using ⍺-particles of energy 3 MeV. The optical band gap data of irradiated films found in the range of In/Sb semiconductor. RBS spectra also support mixing of bilayer. These results show mixing of In/Sb bilayer by swift heavy ion beam irradiation processes.

Page(s): 253-256