Influence of Earthquake Source Parameters and Damping on Elastic Response Spectra

In this paper the influence of effective duration of strong motion, soil condition, magnitude and shape of accelerogram time history on elastic response spectra have been investigated. A total of 106 Iran’s horizontal acceleration components strong motion records are selected. These accelerograms are categorized in accordance with their earthquake parameters and soil condition of recording station and the influence of different soil conditions are plotted in graphs. The influence of damping ratio on the response spectra is also investigated. Analytical results show that the influence of soil condition is very significant on the shape of response spectra. The influence of effective duration of strong motion has been studied by definition based on energy of accelerogram. It can be seen that an increase in effective duration, causes reduction in the slope of response spectra in long period part and increases the spectral values. The effect of damping on response spectra is presented by special coefficient, which depends on the period of the structure, soil condition and damping ratio

Ground Motion Selection and Scaling in Practice

This paper provides and evaluates a very simple and practical procedure for selecting ground motions in addition to compare two common scaling methods based on the uniform hazard spectrum (UHS) method and presents scale factors of the selected ground motions associated with these methods. Evaluation of the proposed approach of record selection demonstrates the efficiency of the proposed method. It also presents proper method of scaling for each soil condition and engineering demand parameter and the obtained scale factors could be utilized directly from this paper in the other studies in this field without any excessive calculational attempts

The Effect of Soil around the Basement Walls on the Base Level of Braced Framed Tube System

According to the 2800 standard, the Iranian code of practice for seismic-resistant design of buildings, the base level refers to the level at which it is assumed that the horizontal movement of the ground is transmitted to the structure. In cases that there are reinforced concrete walls being run by an integrative structure in the underground perimeter, and the surrounding ground is dense and compressed, the base level is considered on the top of the basement wall. In tall structures, due to strong forces and moments at the foot of the structure, examining the location of base level and its movement becomes specially important. The aim of this study was to investigate the impact of changing the properties of the soil around the underground perimeter walls on the base level, taking into account the effects of soil-structure interaction systems. In this regard, the soil-structure system was investigated in two-dimensional models and the location of the base level was identified using shear and drift changes. The results indicated that taking into account the level of the upper stories is possible through performing appropriate walls integrated with the structure even without Compacting the soil around the structure

Efficiency of Hybrid Algorithms for Estimating the Shear Strength of Deep Reinforced Concrete Beams

Earthquakes occurred in recent years have highlighted the need to examine the strength of reinforced concrete (RC) members. RC beams are one of the elements of reinforced concrete structures. Due to the dramatic increase in the population and the number of medium/high-rise buildings, in recent years, the beams of buildings have been mainly designed and executed in the type of deep beams. In this study, the artificial neural network (ANN) with optimization algorithms, including particle swarm optimization (PSO), Archimedes optimization algorithm (AOA), and sparrow search algorithm (SSA), are used to determine the shear strength of reinforced concrete deep (RCD) beams. 271 samples from experimental tests are employed to develop algorithms. The results of this study, design codes equations, and previous research are compared. Comparison between the results shows that the PSO-ANN algorithm is more accurate than previous methods. Finally, SHApley Additive exPlanations (SHAP) method is utilized to explain the predictions. SHAP reveals that the beam span and the ratio of the beam span to beam depth have the highest impact in predicting shear strength

Distribution of Building Nonstructural Components in Height Subjected to Cost of Damage for Low-Rise Office Buildings

Exceeded losses of nonstructural components from structural ones in most demolished buildings in previous earthquakes and its limitation on functionality of critical facilities and building serviceability after earthquakes should be got the point of view for accounting loss of building as a merit for building performance. This paper attempts to demonstrate the significant role of distribution pattern of building nonstructural components in height accounting for economic losses due to seismic excitation. To achieve this purpose a new modified distribution of nonstructural components in height is proposed for three typical steel moment frame models by office occupancy and  comparative assessments between two competing distribution of nonstructural components are conducted. Dealing with discussions, it could be concluded that the economic losses could be reduced by more astutely situating building nonstructural components in height considering type of dominated demands in a specific story without requirement to any alternation in component's type or quantity

Selecting Appropriate Intensity Measure in View of Efficiency

This study attempts to answer the question of distinguishing appropriate intensity measure parameter for performance-based design or assessment, taking into account the efficiency aspect. The comprehensive comparative tables proposed in this paper could be an effective support in the decision making procedure for intensity measure selection, comprising most of the frequently utilized intensity measures for low-rise buildings with different fundamental periods. In addition, since some specific intensity measures are commonly applied in codes, the amounts of standard deviation computed in this study could be very beneficial in answering the question of being worthy to consider another intensity measure, to improve the certitude of structural responses, noting expansion in calculationefforts

Base level Investigation in various buildings and corresponding effective factors

Base level is one of the important parameters in determining the seismic force and preliminary design of structural sections. Base level, According to 2800 seismic regulations, in cases which the basement perimeter is executed with reinforced concrete walls integrated by structure, in addition with surrounding dense soil; set top of basement walls. The critical issue involved in determining base level is horizontal motion of the land. Usually horizontal movement of the Earth is transferred by shear and friction between the edges of the basement walls and foundation, also this process is completed by soil friction between underside of slabs and shallow. Different conditions such as non-same elevated foundations, soil type around building, soil-structure interaction and type of foundation are impressive on location of base level. Other factors including retaining wall openings in basement, basement floors and soil characteristics around the base structures affect base level coordination. As regards there is cleared definition for base level in different regulation all around the world, sometimes engineers cannot comprehend main purpose correctly, or concepts occasionally are interpreted inaccurately. When structure conditions little different from what normally there is, for example, buildings on slope, or structures on deep foundation such as piles, often experts are conflicted by finding location of base level in this status. In this paper investigations about base level in the past years expressed and studied, also, important issues around them are discussed