Progressive collapse studies generally assess the performance of the structure under gravity and blast loads, while earthquakes may also lead to the progressive collapse of a damaged structure. In this study, the progressive collapse response of concentrically braced dual systems with steel moment-resisting frames was assessed under SEISMIC loads through pushover analysis using triangular and uniform lateral load patterns. Two different bracing types (X and inverted V braces) were considered, and their PERFORMANCES were compared under different lateral load patterns using the nonlinear static alternate path method recommended in the Unified Facilities Criteria (UFC) guideline. Eventually, the SEISMIC progressive collapse resistance of models was compared to their progressive collapse response under gravity loads. These studies showed that models under the SEISMIC progressive collapse loads satisfied UFC acceptance criteria and limited rehabilitation objective. The structures had better performance under SEISMIC progressive collapse than models under gravity loads because of more resistance, ductility, suitable load redistribution, and more structural elements that participated in load redistribution. Furthermore, despite studies on progressive collapse under gravity loads, the dual system with X braces showed better progressive collapse performance (more resistance, residual reserve strength ratio and ductility) under SEISMIC loads than the model with inverted V braces.

Floor isolation technique is considered as a new approach in SEISMIC design of structures in which the mass of building at each floor is isolated from the main structural system via SEISMIC isolators. In this case, during earthquake actions, large relative movement between isolated floors and the main structural system at each floor level would be expected. In the current work, numerical studies have been carried out on a typical floor isolated building to investigate the role of displacement constraints (Stoppers) in limiting the gap between the floors and the structural system during SEISMIC actions. A ten-story steel frame structural system located on stiff soil subjected to far-field earthquakes was selected for parametric study in this work. The structure has been proportioned in three different configurations, not isolated, floor isolated and floor isolated equipped with Stoppers. Since using floor isolation improves the structural PERFORMANCES of the system, a fourth configuration for the same structural system with 18% reduction in steel consumption is also taken into consideration. This structure was deliberately proportioned to provide the state of comparable SEISMIC PERFORMANCES between the isolated structure and the nonisolated one. Direct time integration analyses using seven scaled bi-directional earthquake records have been carried out on the same structural system for all its configurations. According to the results of this study, floor isolation is quite effective in improving structural PERFORMANCES of the system. In fact, on average, floor isolation causes significant reduction on lateral displacement of the structural system (more than 50%) if it compares with the nonisolated one. The results also show the benefit of using floor isolation technique in design of structural system by decreasing the construction cost of the building (18% reduction in the weight of structural material) if a comparable SEISMIC performance with the non-isolated structural system is required. It should be noted that, improving in SEISMIC PERFORMANCES of the building or reduction in its construction cost comes in the expenses of large relative movement of isolated floors with respect to the main structural system. In the example used in this study such relative movement (average of seven earthquakes) reached to the level of 0. 1 meter. However, in one of those earthquakes (Imperial Valley, 1979) this relative movement has soared up to 0. 19 meters. Such large relative movement needs complicated non-structural detailing for the building assembly and expensive SEISMIC isolators. To deal with this problem, displacement constraints have been provided for the floor movement using elastic Stoppers. The gap between Stoppers and the floor system is chosen at 0. 1 meter to limit the Stopper’ s functionality in structure only to the case when the system is subjected to large earthquakes. The results of parametric studies on the system with reduced structural weight (configuration fourth) shows a reasonable reduction in relative displacement between floors and the main structure in case of using Stoppers. These results were obtained using nonlinear time integration analyses on the structural system subjected to Imperial Valley earthquake record. According to these results, while Stoppers can reduce the relative movement between floors and the structural system to about 35%, they considerably add to the acceleration of the floor system (up to twice for the isolated structure at the roof level). In addition, the results also show using Stoppers may add to the inter story drift limit of the structure (up to 20%). These shortcomings in using Stoppers in this work can possibly be reduced using Stoppers with different arrangement and sophisticated characteristics.

Hydrocyclones have been used as an operational tool to separate liquids from solids in different industries for more than 50 years. Considering the importance of this issue, many experimental and numerical attempts have been made to estimate the performance of this tool regarding the resulting pressure drop and the separation efficiency (particles separation limit diameter). Most of the numerical studies for simulating the fluid flow pattern inside Hydrocyclones have been conducted using the ‘’Fluent’’ commercial software. The other alternative for this evaluation is the application of CFD in COMSOL Multiphysics. This work is mainly focused on studying the effect of entering tangent velocity and also determining the flow pattern by CFD simulation in the powerful COMSOL Multiphysics software. Thereafter, correlations proposed by a number of authors are compared with experimental data to evaluate their PERFORMANCES. Among them, the correlations suggested by Barth and Koch-Lich showed acceptable accordance with reference data and thus were chosen for sensitivity analysis. Based on the results, three geometrical parameters of the hydrocyclone body have considerable effects on the separation efficiency. The findings revealed that decreasing the outlet diameter and the inlet width result in increasing the efficiency of hydrocyclone while enlarging the body diameter has negative effects on it. Furthermore, the cyclone efficiency is enhanced as the density difference between fluid and solid and the input velocity becomes larger.

The performance of buildings designated as very high importance buildings (such as hospital buildings) according to Iranian SEISMIC Code (Standard 2800) is that, these buildings maintain their operational level in major SEISMIC ground motions (design level earthquake) without major structural damage. This paper discuses the design requirements to reach the purposes in this code and shows that the code regulations can not provide the enough strength for the buildings to operate acceptable during sever earthquakes. To evaluate the code requirements, some R/C moment resistance frames with difference in stories numbers (designated according to standard 2800) was selected and their strength was evaluated based on Instruction for SEISMIC Rehabilitation of Existing Buildings (No. 360), by pushover analysis. The results indicate that the buildings designated as very high importance according to standard 2800, do not remain operationally after sever earthquake.

In solar drying, the moisture content of a product is reduced through the use of sunlight. Solar drying is practiced since civilization for the drying of crops. The dried crop has a longer shelf life and requires less storage space. For crop drying, hot air is required in the moderate temperature range of 40 to 75℃. Solar dryer makes it possible to obtain better product quality. Over the past 20 years, numerous experimental projects have been carried out in the field of solar dryers. Most conventional dryers are not able to operate continuously during the off sunshine time. However, attempts were made to develop uninterrupted solar drying systems by incorporating an energy storage facility and a hybrid mode of operation.  Sensible and latent heat storage methods are widely used to store solar energy. Heat storage materials store energy in the form of heat during sunshine and release it whenever it is required. Biogas backup, Chemical heat pump, Photo Voltaic, and Fluidized bed methods were integrated with solar dryers for uninterrupted operation. In this article, the discussion is made about different dryers. Also, the challenges and scope in the area of the solar dryer are highlighted.