There are several sources of uncertainty in the analysis and design of steel moment resisting frames, the random assumption of each of which can have a significant effect on the satisfaction of performance requirements of the structure. Among these factors, structural parameters can be mentioned, the most important of which are yield stress, modulus of elasticity, sections geometry and structural mass. Evaluating the impact of these factors depends on how the parameters are distributed and modeled. In this study, three common types of uniform, normal and log normal distributions for the parameters of mass structures, yield stress, modulus of elasticity and sections geometry that are random in nature are considered and using Monte Carlo method, the effect of uncertainty of these parameters is considered. The seismic performance of steel structures is investigated. Studies are performed on 4 structures of 3, 5, 10 and 15 floors of steel moment resisting frames with medium ductility, which are designed according to Iranian regulations. In order to model the structures and perform incremental dynamic analysis, Open Sees software was used. In order to evaluate the seismic performance of the structures, fragility curves were used. The results show that the type of distribution does not have a significant effect on the results of applying uncertainties. It is also observed that considering the mass uncertainty, increases the acceleration range in the Collapse Prevention (CP) and life safety (LS), which shows the significant effect of mass uncertainty compared to other parameters.

Jacket-type offshore platforms play an important role in oil and gas industries in shallow and intermediate water depths such as Persian Gulf region. Such important structures need accurate considerations in analysis, design and assessment procedures. Incremental wave analysis for performance-based assessment of jacket platforms is established in 2011 to estimate different limit states and accurate behavior of jacket platform against environmental wave loading. IWA can be appropriate substitute to current pushover practice. The IWA can estimate the collapse-prevention limit state of jacket platforms properly. In addition, an appropriate parameter for ultimate capacity of offshore platforms is introduced which is called Collapse Wave Height (CWH). The CWH can be utilized as a substitute to RSR parameter in the design and assessment of jacket platforms. In this paper, IWA is explained. IWA curves, collapse-prevention limit state and CWH for case study platform is calculated. Effect of deck mass and its distribution on CWH is examined.

Process towers or vertical vessels are among the industrial structures that play a key role in the production process of petroleum products and their derivatives in refineries and oil and gas industries. Due to the vulnerability of these structures in past earthquakes, and the lack of valid regulations and methods for seismic analysis and design of these structures, a case study on a designed and constructed process tower 26.5 meters high, located in Qeshm Island Refinery, has been conducted in this research. Since considering a rigid foundation, without the interaction of soil and structure, may lead to wrong results, in this study, the tower has been modeled in Abaqus finite element software considering soil behavior. The Winkler model used for soil modeling and the seismic behavior of the tower was investigated using pushover and incremental dynamic analysis, and finally, the resulting fragility curve is presented to show the structure's vulnerability at different levels of seismic intensities. In this investigation, the probable failures, including the failure of the body and the skirt, as well as the overturning of the structure, have been investigated. According to the incremental dynamic analysis results, no buckling was observed in the body and the tower's skirt before the tower overturned. The results show that overturning was the predominant failure mode and the probability of this failure mode until PGA=0.1g is approximately equal to zero, and for PGA= 0.35g, this probability is less than 20%. But for rare seismic intensities, the overturning probability is considerable.

Direct analysis method is a new approach on stability design of steel structures. This method consider second order effects by applying lateral force and reducing stiffnesses, however the effective length method consider these effects by increasing column length. The direct analysis method takes the effective length factor unity for all members. Joints displacement, out of straightness and out of plumbness as initial imperfections can be modeled directly or alternatively by applying notional loads in design considerations. Inelasticity and geometric nonlinearities calculated by reducing member stiffness in design considerations. In heavy oil structures, significant gravity loads and column length lead to more second order effects in compare to typical structures. This study evaluates and compares nonlinear dynamic analysis responses of designed heavy oil structures in both direct analysis method and effective length method based on ANSI/AISC 360-10 provisions.

Dhow (LanJ) is a wooden vessel which is traditionally operating in Persian Gulf and Oman Sea. In contrast of its frequent lost, ordinary people believe that it has very good behavior at waves. In this study, by means of seakeeping computer software, authors have calculated its dynamic behavior in waves. Comparison between dhow performances in waves against seakeeping criteria has been made. Then, its operable sea waves are concluded. Then the reason behind people believe has been discussed, thoroughly. The end result is that the typical wooden dhow may withstand in waves of significant wave height of not more than 1 meter.