نشریه آنالیز سازه - زلزله
سال پانزدهم شماره 3 (پاییز 1397)

Determining the dominant force in Jacket design is often one of the main concerns of engineers. In the current study, a marine jacket with a height of 50 meters, with an effective 6 m wave height and a deck height of 10 meters is considered hypothetically. These dimensions is in accordance with the general conditions of the Persian Gulf. The wind load, the regular wave and the random wave load have been applied under the Pierson-Moskowitz, Bretschneider, Mitsuyasu and JONSWAP spectra to the considered jacket and for all stages the jacket base shear has been obtained by using the STRUCAD software. Based on the results obtained in terms of base shear, the random wave with the JONSWAP spectrum yielded the highest base shear and compared to the Pierson-Moskowitz spectrum, 11%, Bretschneider 17%, Mitsuyasu 19%, Regular wave 27%, and wind load 38%, provides more base shear. Thus, due to the lack of sufficient field information in the design of Jackets in terms of base shear, it is recommended to use the JONSWAP spectrum.

Diagrid structures as the structural system in dignified buildings, from the applicational point of view, are framed and piped developed structures which decrease the weight of the structure by reducing the cutting limp. The goal of the present article is to optimize the diagrid structures for reducing the weight of structure, determining the number of classifications and the optimize angle and finally comparing the mono and two-layer diagrid structure for selecting the economic option. Through the present research, doing the optimizing diagrid structure by using the extra-creating algorithms, which made the integrated drive electronic necessary, was considered. The Grasshopper graphical programming extension on the Rhino geometric modelling software supplied the algorithmic optimization by making the written program parametric by the genetic algorithm by Galapagos extension. Optimizing in the written software is done by the genetic algorithm by Galapagos extension in base of output results from Karamba analysis structure engine. The optimizing accessed results show that the optimizing angle of the diagrid structures’ members with horizon line for mono-layer diagrid os 64/01 and for two-layer diagrid structure is 65/77. The optimizing weight of the mono-layer diagrid is less than two-layer diagrid which by attention to the simple structure in the rapid time and less energy consuming, the mono-layer diagrid is selected as the affordable option.

In this study, 4-, 8-, and 12-Story steel special concentrically braced frame (SCBFs) structures were considered in area with high seismically hazard and soil type II according to Iranian's 2800 code provision. Structures are residential use and have regularity in plane and vertical distribution. Structures were modeled using Sap 2000 software to investigate the effect of self-centering ‎motion under seven near-field earthquakes. All models assumed with and without dual system controlling provisions. The results of this research indicate that without dual system provisions, considering the self-centering ‎motion in ‎4-, 8-, and 12-Story SCBFs‎ reduces base shear of structures in contrast with increasing deformation of top floor and column axial force. In average, the self-centering ‎motion‎ dissipate energy more than fixed base one. With controlling dual system provisions, considering the self-centering ‎motion in ‎4-, 8-, and 12-Story ‎SCBFs‎ reduces base shear of structures, whereas increases deformation of top floor ‎and column axial force. Moreover, in this case of study, energy dissipation are more than with controlling ‎one. Considering the self-centering ‎motion in ‎8-, and 12-Story ‎SCBFs‎ reduces base shear of ‎structures and top floor deformations, meanwhile column axial force‎ was increased. It can be seen that in ‎4-, and 12-Story ‎SCBFs considering code provisions had a better results, whereas in ‎8-Story ‎SCBFs ‎neglecting code provisions was accepted.

Nowadays, with the spread of explosive attacks on buildings in the world, a detailed study of the behavior of structures under the influence of explosive loads is a necessity. The explosion is a reaction in which the rate of burning material is carried out at a much higher rate than the sound speed, resulting in a very high temperature and pressure gradient generated and the shock wave is immediately generated and released at a very high speed. In this study, considering the importance of the subject, we examined the behavior of the panel sandwich ceilings under the canwep loads using Abqus 2016 software. In order to validate the results of the numerical examples, we first verified the results of a sample of the reference article and, after correctness of the results, we applied numerical modeling to six models and extracted the results in Excel software. In this research, numerical examples include two groups of roof panel sandwich panels that differ in interior hardening intervals. Both groups under the load of 1, 2 and 3 kg of TNT were located at a distance of 20 cm from the center of the roof and examined the impact of the explosive charge on the distribution of stress and displacements in the samples. As expected, according to the samples, the explosion of the explosive and the increase in distance from the surface of the panel reduced the amount of displacement and stresses on the panel, as well as the distance of the explosive from the surface of the panel and the increase in the amount of explosive material, displacement and The tension on the panel has also increased.

Concentrated major stresses in area of ​​beam-to-column welded connections of steel moment frames have been proposed in the high density demands as a critical factor in connection vulnerabilities. Reducing the stress concentration in the connections can be accomplished with the intentionally weakening of the cross section of the beam connected to the column. By this method, the plastic hing is formed in the weakened section and the demand is included on the connecting components. In this study, the effect of the panel rigidity on the behavior of the beam connection with the reduced bending strength section with the tube has been investigated. Eight connections of various thicknesses have been investigated. Connections are analyzed using finite element modeling under static loading. In this research, it is observed that with increasing the thickness of the web panel zone, the loss of the strength curve decreases and the connection experiences more drift. Also by increasing the thickness the von mises stress in the panel zone decreased. The values ​​of stress and displacement were observed in the tube web in larger thicknesses are bigger. The failure of the column and the connection panel zone in the connections decreased with the increase of the connection panel zone thickness. The lowest energy dissipation is related to the weakest panel zone connection. By increasing the thickness of the panel zone connection, it would be expected that more energy would be lost from the connection. In general, according to the results obtained in this study, application of thickness less than the calculated value in seismic design is not recommended.

Examining the results of calculation and designing of buildings bases on earthquake regulation is very important due to locating of Iran on earthquake belt. Standard 2800 fourth edition is currently the latest regulation of building designing against earthquake issued by the Ministry of Roads and Urban Planning for designing of buildings. This regulation depicts the national determination and the government plans for reduction of the damages resultant from earthquake.In order to better understand the strengths and weaknesses of our country's law and to improve the defects in subsequent versions of the law, we compared the results of designing buildings according to Iran's rules and ASCE / SEI 7-16. In this paper concrete buildings 7 and 8 The height between the floors of 20.3 m and in two types of terrain II and III by Etabs 2016 software have been examined based on the two regulations. Based on studies carried out in accordance with the ASCE / SEI Regulations 7-16 in Iran, the use of a medium-ductile bending frame is not permissible, and the effects of the vertical load of the earthquake should be reconsidered, and it is suggested that the relative deformation for Categorize different individual hazards