A design methodology for hysteretic dampers

Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2002.Includes bibliographical references (p. 71-72).by Bora M. Tokyay.M.Eng

Specimen shape and size effect on the compressive strength of higher strength concrete

The specimen size and shape effects on the compressive strength of higher strength concrete were investigated on different sized cylinders having constant length-to-diameter ratio (l/d), different sized cubes, and cylinders with various l/d for 40, 60, and 75 MPa compressive strength levels. The apparent strength values of 75mm diameter cylinder and 75 and 100mm cube specimens were lower than those of the larger specimens used. Also, the compressive strength was determined to be insignificantly affected by changing l/d as the strength of concrete increases. (C) 1997 Elsevier Science Ltd

Development of high-volume low-lime and high-lime fly-ash-incorporated self-consolidating concrete

The current article presents an experimental study on the use of two types of fly ash ( low lime and high lime) as mineral admixtures in producing self-consolidating concrete (SCC) with the objective of assessing the effects of both types of fly ash on the fresh and hardened properties of SCCs. Within the scope of an experimental programme, SCCs were prepared by keeping the total mass of cementitious materials constant at 500 kg/m(3), in which 30, 40, 50, 60 or 70% of cement, by mass, was replaced by high-lime and low-lime fly ash. The workability-related fresh properties of SCCs were observed through slump flow time and diameter, V-funnel flow time, L-box height ratio, GTM sieve stability test and the rheological parameters ( relative yield stress and relative plastic viscosity). Setting times and temperature rise of SCCs were also determined as part of fresh properties. The hardened properties that were monitored for a year included the compressive strength, ultrasonic pulse velocity, drying shrinkage and chloride permeability. It was observed that the geometry and surface characteristics of fly ash affected the workability properties of SCC mixtures. Nonetheless, the compressive strength of SCC mixtures with 30 - 40% low-lime fly ash replacement was slightly greater than the control SCC mixture at the end of the year, as the amount of fly ash replacement increased losses in compressive strength. As a result of this experimental study, it could be concluded that SCCs incorporating a fly ash replacement of 70% could be produced with improved fresh and permeation properties and sufficient compressive strength

Genetic expression programming for prediction of heat of hydration of the blended cements

This study presents a new approach based on Genetic Expression Programming (GEP) for modeling of variation of heat of hydration of Portland and blended cements. For that purpose, two different GEP models were developed to generate two mathematical equations. In the GEP Model 1, six input parameters such as the ground blast furnace slag replacement ratio (GBFS), ground basaltic pumice replacement ratio (GBP), clinker and gypsum ratio (CG), cement fineness (CF), grinding type (GT) and time (T) were used. In GEP Model 2, three input parameters such as cement fineness (CF), grinding type (GT) and time (T) were used. The results were highly promising in terms of training performances and prediction accuracies and revealed that the proposed GEP models can be used in the prediction of heat of hydration of blended cements. © 2009 Academic Journals

The early heat of hydration of blended cements incorporating GGBFS and ground basaltic pumice (GBP)

WOS: 000205419400002In this study, the effect of blended cements containing additives on the heat of hydration and the rate of heat liberation was investigated. The blended cements were prepared by using clinker, ground granulated blast-furnace slag (GGBFS) and ground basaltic pumice (GBP). Two groups of specimens were prepared by the grinding method of intergrinding and separate grinding. For each group of specimen, two Blaine values of 2800 +/- 30 cm(2)/g and 4800 +/- 30 cm(2)/g and four different ratios of additives, which were 0%, 10%, 20% and 30% of clinker by weight, were used. The effects of the grinding method, the fineness and the amount of additives on the heat of hydration were also investigated. It was found that the heat of hydration was affected by the grinding method. Also, interground coarser blended cement specimens resulted in extended time to reach the second peak compare to the separately ground finer ones. A significant reduction in the total heat of hydration was achieved in the interground coarser specimens with 30% additives. The minimum heat of hydration was obtained from the interground specimens with 30% additives and Blaine value of 2800 +/- 30 cm(2)/g. Due to lower heat of hydration this cement can be used for mass concrete construction

the blended cements

This study presents a new approach based on Genetic Expression Programming (GEP) for modeling of variation of heat of hydration of Portland and blended cements. For that purpose, two different GEP models were developed to generate two mathematical equations. In the GEP Model 1, six input parameters such as the ground blast furnace slag replacement ratio (GBFS), ground basaltic pumice replacement ratio (GBP), clinker and gypsum ratio (CG), cement fineness (CF), grinding type (GT) and time (T) were used. In GEP Model 2, three input parameters such as cement fineness (CF), grinding type (GT) and time (T) were used. The results were highly promising in terms of training performances and prediction accuracies and revealed that the proposed GEP models can be used in the prediction of heat of hydration of blended cements

the blended cements

This study presents a new approach based on Genetic Expression Programming (GEP) for modeling of variation of heat of hydration of Portland and blended cements. For that purpose, two different GEP models were developed to generate two mathematical equations. In the GEP Model 1, six input parameters such as the ground blast furnace slag replacement ratio (GBFS), ground basaltic pumice replacement ratio (GBP), clinker and gypsum ratio (CG), cement fineness (CF), grinding type (GT) and time (T) were used. In GEP Model 2, three input parameters such as cement fineness (CF), grinding type (GT) and time (T) were used. The results were highly promising in terms of training performances and prediction accuracies and revealed that the proposed GEP models can be used in the prediction of heat of hydration of blended cements

Genetic expression programming for prediction of heat of hydration of the blended cements

This study presents a new approach based on Genetic Expression Programming (GEP) for modeling of variation of heat of hydration of Portland and blended cements. For that purpose, two different GEP models were developed to generate two mathematical equations. In the GEP Model 1, six input parameters such as the ground blast furnace slag replacement ratio (GBFS), ground basaltic pumice replacement ratio (GBP), clinker and gypsum ratio (CG), cement fineness (CF), grinding type (GT) and time (T) were used. In GEP Model 2, three input parameters such as cement fineness (CF), grinding type (GT) and time (T) were used. The results were highly promising in terms of training performances and prediction accuracies and revealed that the proposed GEP models can be used in the prediction of heat of hydration of blended cements. © 2009 Academic Journals