In structural analysis, P-Delta effect refers to the changes in internal forces due to P-Delta moment which can be found by multiplying gravity load (P) by the lateral displacement of structure for earthquake lateral load (Delta). The influence of PDelta in elastic response of structures is ignorable, but P-Delta effect should be given more attention when the structure responds in inelastic range. On the other hand, the influence of ground motion duration is magnified when P-Delta effect is considered in the structural analysis. In this paper, to consider the simultaneous effect of ground motion duration and P-Delta effect, an algorithm is implemented in MATLAB which employs OPENSEES for linear and nonlinear dynamic analysis of elasto-plastic systems subjected to long-and short-duration records. The analysis results indicate that the frequency of structural Collapse for longduration ground motions is about twice of short-duration ground motions. The frequency of Collapse also increases when ductility and stability index increase, but decreases when the period of structure increases. Furthermore, the increase of ground motion duration has no influence on the residual displacement of structures, but nonlinear behavior of structures and gravity load effect increase the residual displacements.

Progressive Collapse studies generally assess the performance of the structure under gravity and blast loads, while earthquakes may also lead to the progressive Collapse of a damaged structure. In this study, the progressive Collapse response of concentrically braced dual systems with steel moment-resisting frames was assessed under seismic loads through pushover analysis using triangular and uniform lateral load patterns. Two different bracing types (X and inverted V braces) were considered, and their performances were compared under different lateral load patterns using the nonlinear static alternate path method recommended in the Unified Facilities Criteria (UFC) guideline. Eventually, the seismic progressive Collapse resistance of models was compared to their progressive Collapse response under gravity loads. These studies showed that models under the seismic progressive Collapse loads satisfied UFC acceptance criteria and limited rehabilitation objective. The structures had better performance under seismic progressive Collapse than models under gravity loads because of more resistance, ductility, suitable load redistribution, and more structural elements that participated in load redistribution. Furthermore, despite studies on progressive Collapse under gravity loads, the dual system with X braces showed better progressive Collapse performance (more resistance, residual reserve strength ratio and ductility) under seismic loads than the model with inverted V braces.

In line with the current research on the ultimate strength assessment of ship hull girders, careful understanding of the Collapse behaviour of unstiffened plate elements within the ship hull girders is an important and necessary task. In this paper, the Collapse behaviour of unstiffened plates under longitudinal and transverse thrust is studied by clastoplastic large deflection FEM and the characteristics of the Collapse modes are highlighted.

Estimation of Collapse performance is primarily conducted through Collapse Fragility Curves (CFC’s). The EDP-based approach is the main scheme for attaining such curves and employs IDA. Obtaining CFC’s from IDA results is tremendously time consuming and computationally demanding. Introduction of more efficient methods of seismic analysis, can potentially improve this issue. The Endurance Time (ET) method is a straightforward method for dynamic analysis of structures subjected to multilevel excitation intensities. In this paper, Collapse analysis using ET analysis results to obtain EDP-based CFC’s, has been explained and demonstrated by a model. For verification, the resulting CFC has been compared to that obtained by IDA.

Expansive and collapsible soils are some of the most widely distributed and costly of geologic hazards. These soils are subjected to change in volume and settlement in response to wetting and drying, often resulted in severe damage to structures. Collapsing soils are generally characterized by sudden and large volume decrease at constant stress when inundated with water. A geotechnical engineer needs to be able to identify readily the soils that could Collapse and to determine the amount of Collapse that may occur. Various methods of predicting Collapse from simple and rapidly-performed index have been suggested by several workers in the field. In this investigation, most of the well known Collapses identifying criteria are reviewed and evaluated. New method and interpretations let rapid and safe prediction of Collapse are further discussed in this paper.

Background: This article sought to assess social disorder and respond to questions such as: Is “, social Collapse”,an appropriate term to describe the situation in Iranian society facing various social problems? If this concept is not appropriate, then what is the appropriate concept? How should this situation be explained? Methods: This theoretical-analytical study collected data using the library research method. Results: According to our results, the concept of social Collapse is an inaccurate and unscientific one. Basically because this concept cannot fully explain the status of the Iranian society. The proper concept to describe this term is”,social disorder”, . Unfortunately, Iran is faced with a gamut of disorders all of which are manifested in the various subsystems of the society,these situations generally stem from an ideological view towards Iranians and social culture, homogenizing cultural policies, institutional conflicts, liberalization of economic spheres and their inconsistency when compared with the logic inherent to other social spheres. The role foreign (international) bodies play in the emergence of such situations should not be ignored: and it should suffice that past few decades were testament to this issue which manifested in imposing various forms of sanctions against Iran by foreign bodies. Conclusion: Overcoming social disorders and creating balance in the social system requiresthe implementation of macro-level policy-making in various areas of the governing system.

A spherically symmetric matter Collapses under its own gravity. For the Milky Way, the time scale of Collapse for a spherical halo with NFW density is ∼ 26 My which is very small compared to the age of the Milky Way. The effect of a pressure, obeying a polytrope equation of state is investigated. It is shown that for p ∝ ρ9/8, the time scale would be of the order of 1 Gy. It is also argued that such a polytrope, if considered to be in equilibrium, could explain the rotation curve of the milky way.

When empires and great nations decline, there are many interrelated reasons involved in. Empires are considered to be powerful entities in the world, and via historical surveys, one can identify several important empires that have existed in different eras. Geopolitical knowledge and its constituent concepts (power, politics, and space) are closely associated with empires and can be explored from this perspective. The aim of this research is to conduct a geopolitical investigation of the Collapse of empires. The research deal with the geopolitical factors contributing to the Collapse of empires such as Persia, Rome, Byzantium, Ottoman, Britain, Russia, Spain, and Arab countries, using a descriptive-analytical method and field research. The statistical population consists of 50 specialists and experts in the field of geopolitical studies. The Dimtel method has been utilized to test the conceptual model of the research. The findings demonstrate that variables such as the incompetence and capriciousness of rulers, the Collapse of the domestic economy, the extravagance and corruption of the governing class, oppression and slavery, and internal rebellions have a high level of interaction and a strong systemic connection with other variables. In other words, when a country faces these challenges in terms of its leadership and governance, it becomes unable to effectively address other problems caused by these factors, leading to a crisis and the eventual Collapse of the empire.