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The dual steel resistant skeleton is one of the functional structural systems for resisting against lateral forces induced by earthquakes that in addition to the enhanced ductility possesses high stiffness, dynamic stability, and redundancy. Behavioural pattern of dual resisting systems is based on shear and bending performance modes. This research includes a study on the nonlinear seismic behaviour of dual eccentrically braced resisting frames with knee rods. The extent of the effectiveness of knee bracing has been assessed based on nonlinear time history analyses of the structure subjected to severe three-component earthquake records. A strong near-field ground motion possesses particular characteristics. The existence of high amplitude and long period pulses in recorded strong ground motions along with the severe accumulation of kinetic energy and its short release time, are of noticeable differences between near-field and far-field earthquake records. The particular objective of this research is to evaluate the amplitude of variations in maximum responses and to determine the time history of absolute acceleration, relative displacement, and relative velocity of floors along with the base shear of the studied models. Analysing the results indicate an observable appearance of the effects of large coherent velocity pulses presented in the time history of near-field earthquake records, on the relative lateral displacement of floors and on the rapid propagation of plastic hinge mechanism throughout the primary elements of dual resistant skeleton.

The most important parameter for determining the level of performance and breakdown of buried pipes in the case of earthquake is the maximum value of strain. Vital arteries code, while studying the maximum value of strain, have addressed the seismic behavior of buried pipelines. Static methods don’t have the ability to consider the transient strain effect in their results, so it is necessary to consider another method in determining maximum strain. From the suggested methods to determine the maximum strain in buried pipes during earthquake is nonlinear dynamic analysis of pipes and the soil around it. In this study, using Abaqus software, we have presented a method to calculate the maximum strain of buried steel pipes for gas transfer in soil according to the parameters including earthquake energy like Arias intensity and Housner spectral intensity and using accelerograms. Analyses performed according to dynamic method is nonlinear and modeling has been done for three different lengths of gas transfer buried steel pipes in soil, with the internal pressure using different accelerograms for types of soil in Iran 2800 code. Then, in order to present a united relation to show the relationship between maximum strain of steel pipes and parameters including earthquake energy, in order to apply the considered relation for buried pipes with different lengths and different soils, we have used T/L parameter and the values of a and b (coefficients of fitted diagrams) in each section is expressed according to this parameter

Special composite RC shear wall (CRCSW) with steel boundary elements is a kind of lateral force resisting structural system which is used in earthquake-prone regions. Due to their high ductility and energy dissipation, CRCSWs have been widely used in recent years by structural engineers. However, there are few studies in the literature on the seismic design of such walls. Although there are many studies in the literature on the Direct Displacement-Based Design (DDBD) of RC structures, however, no study can be found on DDBD of CRCSWs. Therefore, the aim of present study is to evaluate the ability of DDBD method for designing CRCSWs. In this study, four special composite reinforced concrete shear walls with steel boundary elements of 4, 8, 12 and 16 story numbers were designed using the DDBD method for target drift of 2%. The seismic behavior of the four CRCSWs was studied using nonlinear time-history dynamic analyses. Dynamic analyses were performed for the mentioned walls using 7 selected earthquake records. The seismic design parameters considered in this study includes: lateral displacement profile, inelastic dynamic inter-story drift demand, failure pattern and the composite RC shear walls overstrength factor. For each shear wall, the overall overstrength factor was calculated by dividing the ultimate dynamic base shear demand (Vu) by the base shear demand (Vd) as per the Direct Displacement Based-Design (DDBD) method. The results show that the DDBD method can be used to design CRCSWs safely in seismic regions with predicted behavior.