فصلنامه رویکردهای نوین در مهندسی عمران
سال سوم شماره 3 (پاییز 1398)

Self-compacting concrete is one kind of concrete under its weight flows and simultaneous with maintaining homogeneity, without need to vibrator can be filled mold and takes the shape of the container. This concrete due to high performance in construction doesn’t have any risk in aggregates separation. Also, self- compacting concrete has high strength and relatively durability. On the other hand, the existence of huge tile waste and sepulture of these waste by ceramic and tile factories indicates the importance of using this secondary product in the other industries, including the construction industry. Also, with apply of waste material environment can be healthy and safe. In present experimental study, firstly the self-compacting concrete mixing scheme was determined. Then, according to the obtained mixing scheme with replacing recycled aggregates with natural particles, samples with 0, 25, 50 and 100 percentages (by volume) have been made. It should be noted water to cement ratio and percentage of high plasticizer are constant. The amount of limestone and silica fume in all of the mixtures have been fixed. In prepared specimen’s slump test to determine efficiency and compression and water-absorbing tests in 3, 7, 14 and 28 days curing have been performed. Results of the present study show generally with increasing waste tile efficiency and compression strength decrease. Although, durability goes up. Also, especially, with replacing 100% of recycled material with exist particles major changes have been observed but up to 75% have not been seen.

The unique properties and characteristics of ultra-high performance concrete as a new material in civil engineering have brought exciting new horizons to the designers. One of these design horizons that could be very applicable in the future is the idea of a composite of ultra-high performance and usual concrete, which has been put forward to make maximum use of the material capacity. This idea is useable in both of the new construction and repair (improvement) of existing structures. As studies and practical applications have shown, composite of usual and ultra-high performance concrete than original concrete structures will be stronger and durable. However, in any composite structures, the integrated performance of the materials is very important and this integrated performance will make through the interconnection resistance between materials. Also, as regards to the newness of composite the ultra-high performance and usual concrete, limited studies were conducted about to continuity strength between these materials. Therefore, the present research is one of a part in the collection studies related to applicable ultra-high performance concrete in faculty of engineering of Tehran University, continuity strength between usual and ultra-high performance concrete with using ordinary tests in a different mode of base concrete preparation has been studied. According to the results of this study, the continuity of the strength between the two materials is highly dependent on the basic concrete level preparation conditions and, if proper level preparation is carried out, will result in better conditions than even the reference standards

Main goal of present study is optimal design of three dimensional flexural frame with using genetic algorithm. Genetic algorithm, it is an evolutionary algorithm based on intelligent search and it is highly efficient in discrete decision making. Also, in this respect, it may be appropriate to optimize the steel frames with the available profiles in the market. In terms of control design restraint, OpenSees software for determining response of structure was used. In continue, OpenSees results with genetic algorithm connected with using Matlab software. Design methodology in this research is LRFD. Also, in present study three dimensional frame including a frame with six stories, two frames with 10 stories under gravity, seismic and wind loads have been expanded. In optimal processing, frames with and without construction restraint analyzed and both of results have been proposed. Results of present study showed that optimal model have high applicable in proposing optimal design.

In recent years, due to the dramatic increase of air pollutants preparation of right air pollution maps and the development of instantaneous air pollution monitoring systems attention of researchers has attracted. According to the data obtained from air pollution monitoring stations, they were not isolated from the error and some of their observations are missing; therefore, it is necessary to use a robust model to refine the data and predict the observations. In the present study, the data’s of three stations in Tehran of air pollutants corrected and predicted by Kalman filter. Results showed that an average accuracy of 92% for the Kalman filter.

Seismic isolation is one of the best-advanced methods for controlling seismic vibrations in buildings, bridges and nuclear facilities. A new Friction Multi-Layer Elastomeric Seismic Isolator (FMESI) has been modeled, analyzed and investigated by ABAQUS finite element analysis software and then, compared to real models. A number of friction cores have been used instead of the lead core therefore, some of the previous isolator problems have been almost resolved. Moreover, Studies show that the proposed isolator provides suitable initial stiffness and acceptable hysteresis behavior under different vertical and horizontal loading conditions and also internal stresses in different layers are acceptable. Also, as a result, , the initial stiffness and overall area of the curves increase, as friction coefficients of the cores increase, although the frictional coefficients must be within a certain range

This research focused on seismic performance of cold formed light steel walls with internal K-braced and upgraded connections under lateral monotonic loading. To do so, first of all an ABAQUS software model for an available experimental specimen was made of internal cold formed K-braced frame and the accuracy of analytical results was proved in comparison with the existing experimental results. Afterwards, four finite element cold formed light steel wall samples were constructed from C section shape with dimension of 2.4 m to 2.4 m and nonlinear analysed under lateral monotonic loading by changing the single member to double cross sections for bracing and chord members connected to gusset plate. Displacement control method loading was applied to all models. For all specimens, the lateral load, stiffness, energy absorption curves in terms of absolute lateral displacement and drift were extracted as well as failure mode and ductility factor. Finally, the double K-braced cold formed members with modified connections showed adequate seismic performance with 1.91, 2.19, 1.85 and 1.03 times increase of shear resistance, energy absorption, stiffness and ductility compared to control specimen, respectively.