JOURNAL OF CIVIL ENGINEERING ISLAMIC AZAD UNIVERSITY
Year:2010 | Volume:3 | Issue:4|Papers Count:7

Recently a wide range of studies and extensive tests has been carried out in order to determine the mechanical properties of dam concrete in fracture for the purpose of nonlinear analysis. In this study, statistical methods are used to improve the obtained results of compressive and direct tension tests on cm cylindrical samples from Jahgin RCC dam site in order to evaluate compressive strength, tensile strength, modulus of elasticity and fracture energy with different confidence degrees and test ages of specimens. The obtained results are used for the purpose of nonlinear dynamic analysis. A numerical model by governing relations on smeared crack approach has been suggested to consider body anisotropic behavior of RCC dams. Two-dimensional linear and nonlinear seismic analysis of Jahgin RCC dam has been performed. The maximum principal tensile stress and crack formation with its propagation pattern through the dam body were investigated. Analyses were repeated by applying suggested model and observed that cracking has been started quickly and had more propagation at the upper part of dams. The results shown that more damage have been formed in the neck of the dams.

Floods are hazardous events for those who live adjacent to rivers. Flood control design needs study of watersheds and subwatersheds which contribute to the flood. In order to determine the contribution of each subwatershed to the flood in downstream, a flood index can be used. In this study, the effect of rainfall spatial distribution on the flood index was investigated. Results from HEC-HMS model showed that in Bakhtiary basin, rainfall spatial distribution affects the flood index considerably, especially for larger events. Priority of subwatersheds in which generate the downstream flood should affect on peak outflow and flood index as well. No correlation was observed between subwatersheds' curve number and the flood indexes. With increasing rainfall depth in subwatersheds with short concentration times, spatial distribution of rainfall had stronger affect flood index. Lower effect of spatial distribution on flood index was observed in larger subwatersheds with concentration times. The results also showed that if no spatial distribution was assumed, the flood index decreases with increasing subwatershed area.

Recycled asphalt pavement (RAP) has been studied in Iran and other countries, and also many methods such as hot or cold recycling, in place or in plant, has been designed and implemented. RAP is the removed and/or reprocessed pavement material containing asphalt and aggregate. The use of RAP in asphalt pavement has become a common practice in the construction of new, and reconstruction of old, hot mix asphalt (HMA) pavement. But little research has been done to examine the potential of incorporating RAP into concrete. Since RAP contains asphalt, it is very likely that the toughness of concrete made with RAP could be improved. In the present study, the mechanical properties of RAP incorporated Portland cement concrete were investigated through laboratory experiments. Two types of RAP (coarse and fine RAP) materials were considered. The results from this study indicated that RAP could be incorporated into Portland cement concrete without any modification to the conventional equipment or procedures. Without any treatment, there was a systematic reduction in the compressive and split tensile strengths with the incorporation RAP in concrete. Notably, the energy absorbing toughness for the RAP incorporated concrete has been significantly improved.

The Application of Space Structures to Residential, Administrative and Commercial buildings requires particular investigations in order to learn the dynamic characteristics and related dynamic parameters of such structures for design purposes, a topic that has not been included in the related codes of practice. In this paper a method for the calculation of the natural frequency (and hence period of vibration) of these structures has been presented. Also, a series of relationships has been introduced for the estimation of the ultimate lateral load of such space structures. The results obtained from the methods presented here have been compared with the results of the eigenvalue as well as the nonlinear static (pushover) and dynamics analyses. It has been shown that a good agreement exits between the results of the authors’ method and the numerical analyses.

Nowadays rate of changes in construction and mass building industry is increasing that cause of need to more attention to strategic planning and especially strategic planning for human resources management. Human Resources Who Are Working In Construction And Mass Building Industry, Have Many Problems And For Finding Out The Solution Of Their Problems, We Need Strategic Planning For Managing Of Issues Of Human Resources. Optimization Of Working Conditions And Facilities For Human Resources, Will Lead To Maximum Output For Activities. In This Article, We Will Discuss About Main Issues About Human Resources And The Better Ways Of Managing Of Human Resources. For This Research, We Also Have Used A Questionnaire With Four Answers For Conducting An Opinion Poll From Construction Managers Of Grade Number One Contractors (Maximum Level Of Competence).

The effects of passing trains and the resulting ground borne vibrations on people and structures have traditionally been the subject of interest to many researchers. There is always demand for perfecting isolation methods of buildings and other structures near the railway tracks. Oscillations initiated at the wheel rail contact surfaces travel through the soil and end up to the structures in the vicinity of the tracks. There are also noises arising from the contacting metal surfaces which can add to those harmful effects. It is the purpose of this article to present an investigation into the effects of such ground borne vibrations on a model structure near a high speed train track. ANSYS engineering software was used for modeling of the selected building.To excite the model structure, sample inputs for peak particle velocity are chosen from recommendations by ISO14837-1 standard. Frequency analysis of the output data from the software and comparison of such output with ISO14837-1 standard predicts some harmful effects such as plaster cracking of the building.In order to reduce such harmful effects, mechanical dampers were added to the model structure. Addition of such dampers effectively reduced the level of vibrations and consequently reduces the harmful effects on the model building.

One of the applications of the long water conduits is transferring water between basins that are far apart. These kind of conduits have a slight slope and there is a possibility of air entrance into them. "Air blow back" means moving big air pockets against flow direction and it can be destructive in closed conduits. In this paper the motion of big air bubbles in low gradient conduits with little dimensionless discharge is simulated using FLUENT software and VOF method. The results show that air blow back doesn’t happen in such a condition.