Journal des structures en acier et de la construction

Lattice Transmission Towers (LTT) and the associated transmission line systems are important infrastructure in modern society. Due to the complicated load conditions and the nonlinear interaction among the large number of structural components, accurate structural analysis of the LTT systems has been a challenging topic for many years. Still today there are some gaps between research and industrial practice. This paper presents a summary of research outcomes from current literature. Recent developments in structural modelling and failure prediction technology are reviewed in terms of connection joints, individual members and structural systems subjected to static and dynamic loads. The advantages and disadvantages of different approaches have been compared. Finally, the knowledge gaps, associated challenges and possible research directions are highlighted

From the time that Islam came to Iran, Iranian through Islamic centuries until now a garden is a kind of paradise in people opinion. Surely the reason that caused such belief is dryness of Iran plateau. In the ancient pieces found in Iran, one can see the validity of the gardens, in form of initial stage of time from the mountains and long periods big Iranian plateau, they cultivate their forms, sketch different aspect of their life and their opinion on the earthenware. On some of these pieces, trees surround the river, and some others show the river in four parts. This kind of crossing designation that has an axis longer than another one, this form of design called Chahar Bagh. This type of design is common in Sassanid period (642-224). Respect to water and even worshiping flowing water and river basin, is common in this period. In Sassanid period rulers’ selected particular place to sketch their religious view and descriptions about their victory in huge stones, in each place a river basin that was overflowed by spring is created at the foot of stone. A little more than a millennium, one of Qajar king in 19th century 13th Hijra selected such place in south of Tehran called ray and ordered to create a portray of him carved in stone while he sat on his throne. Because the water is a fundamental factor for the creation a garden, so its source has a vital importance.

The anti-corrosive properties of (E)-3-styrylquinoxalin-2(1H)-one (STQ), (E)-1-benzyl-3-(4-methoxystyryl) quinoxalin-2(1H)-one (BMQ) and (E)-3-(2-(furan-2-yl) vinyl) quinoxalin-2(1H)-one (FVQ) were analyzed by different techniques such as: potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), weight loss (WL) and molecular modeling by DFT method and Monte Carlo simulation studies. All quinoxaline derivatives showed appreciable inhibition efficiency. Among the quinoxaline derivatives studied, BMQ exhibited the best inhibition efficiency. The results from the experimental and theoretical investigations show that the order of inhibition efficiency by the quinoxaline derivatives follow the order BMQ > FVQ> STQ. The experimental results suggest that the three tested inhibitors function as mixed-type compounds and the inhibition efficiency increases with the increase in inhibitor concentration and decreased with temperature. Adsorption of the three compounds on mild steel (MS) surface obeys Langmuir’s isotherm model. The theoretical study by DFT method, Monte Carlo simulation and radial distribution function (RDF) provided strong evidence that the inhibition efficiency of quinoxaline derivatives is due to their ability to adsorb strongly at the MS surfaces, which is supportive of the obtained experimental results.

This research highlights the effect of concrete cover on the behavior of ultra-high performance fiber reinforced concrete rectangular solid beams under pure torsion. The main parameter in this research is the thickness of concrete cover which is varying between 21 and 52 mm. For this purpose, four under-reinforced ultra-high performance fibre reinforced concrete rectangular solid beams were cast and they were tested under pure equilibrium torsion. The test results verified that the torsional resistance at peak and crack loads were improved up to 113% and 134%, respectively, of the estimated value based on thin walled tube theory. Moreover, all of the twisting angle at ultimate load and shear strain in concrete were found to decrease up to 64.9%, 40.1%, respectively. In addition, both strain in longitudinal reinforcement and strain in stirrup were reduced up to 50%. The space truss analogy was modified to be compatible with this parameter effect. The modified model showed that it has a good agreement with test results.

Super 304H austenitic stainless steel tubes containing 2.3 to 3 (%wt) of Cu is mainly used in superheaters and reheater of ultra-supercritical boilers. Welding high alloyed steels such as stainless steels can result in local variation of alloying elements within the weld metal and such segregation may affect the high temperature properties of the weld joint. It is preferable to control the solidification structure of the weld by altering the prevailing thermal gradients in the weld pool during welding. The effect of current pulsing on microstructure and hot tensile properties of filler added gas tungsten arc welding (GTAW) of super 304H is studied. Current pulsing is found to be beneficial in improving the hot tensile properties of super 304H GTAW joints at all test temperature, which is attributed to the grain refinement, increase in frequency of high angle grain boundaries, reduced segregation and finer carbonitrides precipitation.

The presence of enclosure has been a significant characteristic of Persian gardens in Pre-Islamic and Islamic eras. This concept is also reflected in Persian ate miniature painting where buildings are enclosed by a light fence or a wall. In some cases, especially house gardens, the wall looks much stronger, probably to protect the security of the enclosed area. The organic arrangement of natural elements in the garden associated with the pavilion, however, is in contradiction to the presence of the enclosure. It can be said that in numerous paintings, water is not enclosed anymore, but it is the building (and the paved area close to it) that is covered by a transparent barrier or a well. Traditional Iranian towns highly appreciate the sense of privacy in their old building. For centuries, Iranian houses were divided into two parts “Inside” and “outside”, in which family members solely used the first part while guests used the latter as well. Despite the importance of privacy in traditional Iranian culture, Iranian people were not isolated, and social contacts had an importance. In Persian garden can see two barriers: the decorated wall which separates the urban fabric from the garden and the fence which separates the paved area intended for sitting from the planted area. In this subject, it is appealing to see that these two enclosures divide the main frame into three layers of story in which three different groups of figures are located.

In order to accurately analyze the mechanical behavior of the steel-concrete composite beams in construction stage, firstly the change law of the shear strength of the stud connectors with the concrete age was studied using the push-out test, in which the time-dependent shear strength formula of the stud connectors was obtained. Secondly, model tests of two simply-supported curved composite beams were carried out during the casting process of concrete slab, the ANSYS finite element models were build with the time-dependent shear strength formula applied in it, and then the experimental and numerical results were verified for each other. On the above basis, a three-span curved continuous composite beam bridge was taken as the sample, by which the influence of the stud connector’s timedependent shear connector strength on the stress behaviors of composite beam in construction stage was studied. The analysis results indicate that the shear strength and stiffness of stud connectors cannot be ignored even when the concrete is in rather early stage, and the early shear strength increases more quickly, whereas the later shear strength slowly. During the segmental casting process of concrete slab, if the casting time interval is between 6 hours and 7 days, the time-dependent characteristics of the early composite action should be considered in the stress behaviors analysis of composite beam in construction stage. Meanwhile, for the hardened concrete segment, the relative slip between the steel girder and concrete slab should also be considered, or else unsafe calculation results will be induced.

Steel plate shear walls (SPSWs) have been frequently used in seismic design and retrofit of buildings over the past three decades or so. Employment of infill plates made of low yield point (LYP) steel with considerably low yield stress and high elongation capacity is believed to provide the possibility in order to improve the structural and seismic characteristics of such lateral force-resisting systems. Among the various benefits is the early yielding of LYP steel infill plates, which can result in greater energy absorption capacity and limitation of the plastic deformation demand to the surrounding frame structure. On this basis, a case study is performed using numerical simulations and reported in this paper on the seismic retrofit of SPSWs using LYP steel infill plates of double thickness. It is shown that the retrofit of a steel shear wall using a LYP steel infill plate of double thickness can result in desirable plate-frame yielding sequence and interaction. Moreover, this retrofit strategy can improve the initial stiffness, buckling stability, and energy dissipation capacity of the existing SPSW system.

Steel plate shear walls (SPSWs) have been used as the primary or part of the primary lateral force-resisting system in design and retrofit of buildings. Development and use of low yield point (LYP) steel with considerably low yield stress and high elongation capacity nowadays provides the possibility to design SPSW systems with improved serviceability, structural performance, and enhanced energy absorption characteristics. This paper provides a review of recent studies performed by the first author on the seismic design and retrofit of SPSW systems using LYP steel material. The results and findings of these studies form the groundwork for future research in the design and detailing of cost-effective high-performing SPSW systems.