نشریه عمران و پروژه
سال پنجم شماره 4 (پیاپی 50، تیر 1402)

Concrete and rebars should have a good bond behavior so that there is no slip between rebars and concrete under the service loads. On the other hand, one of the major disadvantages of steel bars is their vulnerability to corrosion. Covering bars as a solution is also costly and cannot be implemented in all projects. So one of the most suitable alternative methods is the use of GFRP bars. Other ways to compensate for the weakness of the concrete tensile strength as well as its low ductility are the use of different fibers. Concrete with polypropylene fibers is highly ductiled compared to conventional concrete and is completely scattered in concrete and creates isotropetic conditions and can prevent cracks. Therefore, in this study, the effect of polypropylene fibers on concrete compressive strength and bonding strength between concrete and GFRP rebar was investigated experimentally. For this purpose, the amount of this type of fiber is selected 0.15, 0.30 and 0.45 % volume of concrete, and 15cm cubic concrete samples were made in three types of 350, 400 and 450 grade and were cured at 7- and 28-day ages. In this study, the rebar diameter of GFRP was chosen 8 mm and rebars were embedded inside the concrete in a length five times the rebar diameter, and 28-day concrete samples were tested through pull-out and compressive resistance tests. Finally, the compressive strength of the samples and the force-time curves from the pull-out test were assessed. Average compressive strength values, slump values, maximum force and other important parameters were discussed. The results showed that the bond resistance between the polypropylene fiber-reinforced concrete and GFRP rebar increased with the increase in the amount of fibers. Adding fibers also has a relatively good effect on enhancement of the compressive strength of the concrete.

Traffic accidents usually cause not only significant human casualties, but also significant economic losses. Therefore, the prevention of traffic accidents to maintain public safety and reduce economic losses is the concern of the countries of the world. Macro-level road safety studies provide the possibility of identifying influential factors that play an important role in creating safety policies for vehicle drivers. The development of appropriate statistical methods for the analysis of traffic accident data is a fundamental line of research in the field of traffic safety analysis. The main purpose of this study is to investigate the effective factors in the occurrence of traffic accidents in accident-prone areas within the city. Also, appropriate solutions were presented to prevent accidents caused by traffic violations, which is one of the important parameters. The studied area is from Imam Hussain Boulevard to Navab Crossroad, which was extracted based on the available information, including the number of accidents with damage, injury and death, and traffic violations in a 4-year period (2019-2022) in the Highway Police. SPSS software was used to analyze the data. Due to the small amount of data, Pearson's correlation coefficient was used to measure the relationship, and due to the acceptance of linear relationship between research variables, linear regression was used to find the relationship equation. The results showed that 82% of the causes of accidents in the mentioned area are traffic violations. And most of the main causes of accidents are, in order, failure to pay attention to the front 41%, failure to respect the right of way 28%, sudden change of direction 16%, failure to observe the horizontal distance 11% and failure to observe the longitudinal distance 4%. Also, the increase in accidents can be prevented by providing solutions such as police presence, law enforcement, installation of traffic control cameras, road network calming program, and accident hazard training.

Traffic accidents are a global health challenge that kills millions of people annually. Assessing the trend of mortality from traffic accidents is an important step in identifying effective factors in traffic accidents and understanding the effectiveness of targeted interventions and measures to reduce deaths. The aim of study was to conduct investigating the trend of mortality from traffic accidents in Iran for the period 2018-2021. In this study, the trend of fatalities in different provinces of Iran compared using the factors of length of road and accident rate in the province. Data collected from the Forensic Medicine Organization and Road Maintenance and Transportation Organization websites. This data analyzed using descriptive statistical methods in Microsoft SQL Server 2020 and Microsoft Power BI 2023. During the studied period, 66,303 people died in traffic accidents in Iran. The results show that the ranking of provinces in terms of the fatal traffic accidents based on number of accidents and road length is such that the provinces of Alborz, Bushehr and Qom have the greatest amount of index value that indicating a higher risk of accidents in these provinces. This report provides valuable insights for policy makers and health system management in developing effective strategies to reduce mortality caused by traffic accidents.

In previous published literatures it was stated that superposition law might be valid for ground improvement techniques consisting of prefabricated vertical drains (PVDs) along with surcharge and vacuum preloading. Even some professional geotechnical engineers might think of this false idea that superposition law might be valid in such ground improvement techniques. It was shown that the superposition law is not valid because of the hydro-mechanical coupling interactions which exist between vacuum and surcharge preloading. A case history was presented and Finite Element Modeling (FEM) was used for verification and the demonstration of coupled consolidation interaction between vacuum and surcharge preloading. Three main parameters as settlement, lateral displacement, and water excess pore pressure were evaluated for different scenarios. The results that are based on a macro-element approach can be used for better comprehension of the working mechanism of combined treatment systems. Considering the results of this literature, a complex combined vacuum and surcharge preloading can be broken in simpler cases that can be used for either deriving analytical or empirical solutions.