Ehsan Mostavi

Evaluation of Self-Healing Mechanisms in Concrete with Double-Walled Sodium Silicate Microcapsules

AbstractThe objective of this study is to evaluate a new generation of self-healing materials that hold promise for better durability and performance. The in situ polymerization method was used to develop double-walled microcapsules. The microcapsules were prepared in a single batch process containing sodium silicate as the healing agent encapsulated in double-walled polyurethane/urea-formaldehyde (PU/UF) microcapsules. Double-walled microcapsules provide enhanced durability at high temperatures compared with single-walled microcapsules while preserving adequate interfacial bonding of microcapsules. A parametric study was carried out to investigate the effect of different parameters such as agitation rate, pH, and temperature on the performance of the microcapsules and to determine the optimum microencapsulation procedure. The prepared microcapsules were then incorporated into self-healing concrete beams. To monitor the healing process of the cracks, microcracks were created by imposing a certain magnitud...

User satisfaction and energy use behavior in offices in Qatar

The occupant behavior significantly contributes to the total energy use in buildings and its understanding is greatly needed in energy analysis/simulation studies. Uncertainties about the occupant behavior adversely affect the building performance predictability of the simulation models. As field data in Qatar on occupant energy use and behavior was unavailable, we conducted an environmental satisfaction and energy use survey in the city of Doha, Qatar in seven office buildings. Building occupants were highly satisfied with their work environments with respect to most of the environmental parameters excepting acoustics. Access to operable controls such as windows, thermostats improved their satisfaction. Subjects in private offices were more satisfied with their work environments. We noted the self-declared productivity of respondents to be high in general. It was significantly higher in offices with better occupant access to temperature controls. Noise level dissatisfaction was the highest in high partitioned cubicle offices and satisfaction was high in open plan offices. These findings provide vital design direction for new offices and environmental systems design and for managerial motivational campaigns. Practical application: Using field study data, we analyzed the occupant behavior and environmental satisfaction in offices in Doha, Qatar. The Middle East in general and Qatar in particular are known to consume enormous energy for buildings leaving a large ecological footprint. The finding of this study informs the designers of air-conditioning systems about the user behavioral patterns. Further, these findings help the building managers in designing targeted energy awareness/saving campaigns, as user motivation is vital in energy saving.

Investigation of Leveraging BIM Information Exchange Standards for Conducting LOD-Based Cost Estimating

Building Information Modeling (BIM) is a digital information management system that can facilitate workflows and delivery of information in facility projects. Cost estimating is one of the uses of BIM that has the potential to reduce considerably the time and cost required for estimating construction cost of a building project. In this use, type of materials along with their quantities and properties are extracted from building information models and mapped to a cost estimating database in order to estimate the cost. However, interoperability issues currently exist in the industry for the exchange of information from BIM authoring software to cost estimation tools impedes reaching to the full potential efficiency in this use. This paper identifies common information exchange workflows between BIM authoring and cost estimating tools and discusses their advantages and issues. It continues with studying potentials in leveraging open information modeling standards for addressing the identified shortcomings in the workflows. Next, a Level Of Development (LOD)-based cost estimating framework is proposed that uses open information modeling standards for addressing inefficiencies in different detail levels of cost estimating approaches commonly being practiced in the industry. This framework facilitates automated digital information exchanges in the process of using BIM for cost estimating and promotes the implementation of BIM-based cost estimating from early stages of projects.