مجله علوم و مهندسی زلزله
سال دوم شماره 2 (پیاپی 3، تابستان 1394)

On December 20, 2010, an earthquake with a moment magnitude of 6.5 has been occurred in south-east of Rigan in south of Kerman province. The second strong event was happened 37 days after the first event on January 27, 2011 with a moment magnitude of 6.2 in south-west of the first event. Previous studies indicated that the occurrence of an earthquake can change the distributed stress in surrounding region and caused triggering other events. We have calculated the coulomb stress changes due to the first earthquake in the hypocenter of the second earthquake in order to investigate the effect of first event on the second event. This study showed that the stress has increased about 2.8 bar (0.28 MPa) in the hypocenter of the second earthquake. Right-lateral displacement on the causative fault of the first event based on the tectonic and stress pattern of the region can be a cause of left-lateral displacement on the second event causative fault. Besides, in order to investigate the effect of the stress change on aftershocks distribution, we have calculated the coulomb stress changes due to these events on optimally oriented faults. Our calculations showed that more than 70 percent of these aftershocks distributed in places where the coulomb stress changes have been increased and have a positive amount. Coulomb stress changes due to these earthquakes on the surrounding right-lateral faults have been calculated and showed that the stress has been decreased on the central and north-west parts of bam fault and has been increased in the south-east part of this fault.

liquefaction potential in terms of successful liquefaction prediction. As seen in Figure (2), M100 and M10 models reached 100 percent successful prediction. This is while the M1 achieved about 82 percent. Thus an 18% improvement is observed by using new method to evaluate liquefaction potential. Figure 2. The results of the different models in the evaluation of liquefaction potential. Besides, an advanced software system for the analysis of ANN and FCM-ANN methods was designed by the authors in Language C# with Microsoft Visual Studio 2012 and the SQL Server 2012 database entitled PILA (Professional Intelligent Liquefaction Assessment).

Extensive areas of the earth are covered by unsaturated soils. Besides, construction of fills, embankments and earth dams are related to compacted soils, which are a very widespread class of unsaturated soils, and there are many geotechnical problems with these soils. The unsaturated soil is assumed to be a three-phase porous media with a solid phase and two fluid phases, water and air. Therefore, considerable attempts have been made to explain or to predict shear strength and volume change behaviour of unsaturated soils in terms of effective stress. Bishop [1] modified classical expression of effective stress for saturated soils to the unsaturated soils in the following form: s¢ = (s- pa) + c(pa - pw) in which s¢ is effective stress, pa and pw are pore air and pore water pressure respectively, (pa - pw) is suction and c is a parameter that mainly depends on degree of saturation. Many researchers showed that the use of a unique effective stress relation was not fully satisfactory to describe the various aspects of unsaturated soil behavior. The more realistic behavior of unsaturated soils could be explained using state variables and two independent tensorial variables (pa - pw) and (s- pa) i.e. the total stress and suction, respectively) and state surface of void ratio (e) and degree of saturation (Sr) that provide the variation of them with applied total stress and suction. For a given soil, if the fabric does not change significantly, void ratio and degree of saturation are main factors controlling permeability. There are also some empirical relationships based on suction. Thus the permeability of water and air are functions of void ratio and degree of saturation. To obtain the governing equations for the mechanics of unsaturated porous media, the continuity relations of water and air and the dissolved air in water (Henry’s law) are used. The motion of water and air can be described by generalized Darcy’s law. The total mechanical equilibrium is derived by summing of linear momentum balance of three phases and neglecting relative acceleration of fluids. The basic approach in the incremental step-by-step solution is to assume that the solution for time t is known and that the solution for the time t+dt is required. In large deformation analysis, special attention must be given to the fact that the configuration of the body is changing continuously. In the updated - lagrangian (UL) formulation, all static and kinematic variables are referred to the configuration at time t, and the second Piola-Kirchhoff stress and lagrangian strain tensors can be employed effectively at time t+dt. For linearizing, we use the Jaumann stress increments instead of second Piola-kirchhohh stress increments. By using the appropriate stress-strain relation for unsaturated soils and the weighted residual methods, the integral equations are obtained. Utilizing the appropriate shape functions, the basic finite element equations are obtained. In the solution of the nonlinear response, the governing equation must be satisfied at the complete time by using a stepby- step incremental analysis and an iteration procedure like modified Newton-Rophson method is used. For a quantitative solution, the resultant equations are discretized in time by Newmark’s solution and the final finite element equations are obtained. Finally, by the UDAMN finite element code, which developed by authors, two problems, i.e. the settlement of unsaturated ground under loading and step construction of an unsaturated embankment, have been solved by this method.

Building structures damaged by a seismic event may be exposed to the risk of aftershocks or another event within a certain period. Major earthquakes that are considered as ‘main shocks’ are typically followed by smaller earthquakes known as ‘aftershocks’, which originate at or near the rupture zone of the larger earthquake. In order to gain insight into steel frame building behavior under main shock - aftershock events, it is required to simulate the building subjected to possible seismic hazards considering beam to column connections. In current research, a moderate moment resisting steel frame has been subjected to multiple earthquakes to emphasize the importance of decision-making on destruction or repair of damaged structures. The research has focused on frame damaged connections and has hypothesized that the damages to the connections are prior to any damage to the structure. The purpose of the research is to investigate and mechanize the behavior of steel frame connections in both main and aftershock quakes. Since beam-to-column connections in steel moment resisting frames may suffer an extremely low cycle fatigue in both main shock and aftershock, the focus of this research is based on the low cycle fatigue (LCF) parameters. For achieving a comparable study between main shock and aftershock events, the finite element method has been adopted. To verify the finite element model with an experimental program, a steel connection with accessible details has been numerically analyzed under the same load algorithmas in the experiments. In order to describe the analysis results, the appropriate parameters to low cycle fatigue (LCF) have been adopted. Plastic and rupture strain represents local buckling and damage in welding near the access hole and the trend of the mentioned parameters along the beam width represented a promising agreement between numerical and experimental outputs. Meanwhile, hysteresis graph related to cyclic loading at the beam tip and displacement have been compared between experimental and numerical results. The equivalent plastic and rupture indices can be quantitatively utilized to predict low cycle fatigue and local rupture mechanisms of the connection (beam and column). A plastic strain of 1.8 and a rupture index of 0.045 represent local yielding. In loading cycles in accordance with the experiments, in the cycle 21, the top flange yields sooner, and LCF parameters in welding are more than the metal. The trend of output graphs indicates reduction and increase of yielding indices due to stiffener plate in beam web and access hole respectively. Subsequently, the suitable properties of the nonlinear rotational springs have been acquired from hysteresis graph and IMK model. These springs stand for beam-to-column connections and accelerate solution process. Furthermore, instead of considering all possible damage mechanisms that make it time consuming to investigate the connection under the aftershock, the change of these nonlinear springs properties include simplified damages. The selected main shock record belongs to Bam acceleration time history. This record has been induced to the frame. Based on the obtained results, the critical connection was detected that is susceptible to fracture in following shakes. The prone connection has been zoomed in again, and LCF parameters (plastic and rupture indices) for the connection components have been represented. The connection components for the column are composed of left and right flange, top and bottom stiffness plates and panel zone. The beam components includes top and bottom flanges, beam web and bolts. After gaining the hysteresis graph and related envelope points, the nonlinear spring properties have been reassigned. This process ensures considering connection damages in the frame. The frame was subjected to an aftershock event that occurs with a time delay of 13 seconds after the main shock. The aftershock record was selected from a time period of the main shock acceleration record which has the highest amounts. In order to consider the effects of maximum aftershock acceleration on the connection behavior, the maximum values had been selected varying from 1/2 to 1/6 proportional to the main shock. The results of the analyses represent that during the aftershock, the column reacts considerably as well as the beam web, compared to the main earthquake case. During induction of the main shock, maximum values of plastic and rupture strain in beam web were 1.89 and 0.033, respectively. These parameters have been increased to 3.88 and 0.689 in an aftershock of 1/2 of the main shock peak acceleration. The column suffers from local buckling in the flange next to the connection. The maximum values of plastic and rupture indices are 1.35 and 0.031 and have been increased to 3.31 and 0.241 for a 1/2 main shock acceleration earthquake. The LCF parameters of the connection under aftershock have been reduced due to the reduction of peak acceleration. The location of peak parameter occurrence changes and is not constant. In some cases, the panel zone, and in some other, stiffness plates react the most to the loading.

During decades, engineers have tried to build safer and more economic structures. Since establishing primary structural design codes, it has been presumed that “strength” of a structure is synonymous to its “performance”. However, during many years by studying various structural damages occurring during strong ground motion earthquakes, it is obvious today that increasing strength of a building may not result in safer or stronger structure with better performance [1]. Park and Paulay [2] stated that the distribution of strength through a building is more important than the design base shear itself. As they stated, in order to achieve a better structural performance, two important issues should be devised. First, structures should be designed such that plastic hinge formation during nonlinear behavior of the building would occur in all beams before columns. In other words, weak beam/strong column mechanism should be assured. Second, high shear capacity of elements should be supplied to ensure the prevention of brittle failure of main structural elements. This is the case that our experiences during past strong earthquakes have shown that these issues are seldom achieved through applying force based seismic design code regulations. This was the true start to performance based seismic design [1]. During years, researchers found that although strength is an important issue to control floor displacement, the damage potential of structures should be directly related to deformations rather than strength. In the last twenty years, this concept has led to development of a large number of alternative seismic design philosophies based on deformation capacity of structures [3], among which a few methods are suitable as a standard method for implementation in new modern design codes. One of the most important methods is direct displacement-based design method (DDBD) that was introduced by Priestley in 1993. This method is rather more complete and simpler to apply, which has been also used for a wider category of structures [4].The main difference between DDBD and the traditional force-based design method is that DDBD characterizes the structure to be designed by a singledegree- of-freedom (SDOF) representation of performance at peak displacement response, rather than by its initial elastic characteristics. The characterization of the structure by secant stiffness avoids the many problems inherent in force-based design where initial stiffness is used to determine an elastic period, and forces are distributed between members in proportion to elastic stiffness [4]. In this article, the authors aim to consider performance of various level steel structures, which are designed by two completely different design approach; DDBD and a traditional forced-based design method. During this research, two goals are evaluated: the comparison between two displacement- and force based design, as well as the accuracy of formulations that are determined target displacement and damping capacity of the steel frames. This is because direct displacement-based approach is configured based on concrete frames and some correction are implemented in formulations to predict steel frame performance. Hence, three different regular moment resisting steel frames (MRF) with various heights: low, medium, and high-rise buildings, say 4, 10, and 16 stories, are designed by DDBD and the Iranian code of practice for seismic resistant design of buildings, standard No-2800 (the 3rd edition). Seismic behavior of all structures is examined by dynamic nonlinear time history analysis under a 7- acceleration record group. All members of this group have a response spectra matched to the design spectrum of the buildings. Extensive analysis is carried out and the results are compared together. Primary considerations show that the DDBD-buildings are so heavier than the similar 2800-buildings. These differences are much greater with increasing level of the steel frames, which is related to larger design base shear in DDBD approach. However, by considering drift ratios of the floors in the three frame structures, it is seen that DDBD-buildings is very stronger than they need to be. Differences between drift limit and drift ratios of the floors are obviously so large. This may be referred to the target displacement, design displacement profile and needed damping capacity of the frame. On the other hand, 2800-buildings are not meet drift limits specially in below levels of the structures, but by a rather simple modification, they may behave better. It should be noted that the weight of the 2800-buildings are still much lighter than the DDBD-buildings. Finally, it is expected that DDBD with some modifications for steel moment-resisting frames is a rigorous method that is a viable alternative to the current forced based design methods, which can consistently predict seismic behavior of all various level steel structures during strong ground motions. On the other hand, although steel frames designed by forced-based code have previously satisfied their design criteria, they may not be reliable to predict their performance during real earthquakes.

This paper by presenting the guiding principle of disaster risk reduction, the key concepts of Islamic teaching, and the views of Islam on disaster and earthquake in particular; intends to correlate between them with the objective of developing an effective disaster risk awareness and preparedness, especially among a religious community, toward risk reduction and safety. The paper also tries to clear the existing misconception of assuming that disasters are due to God’s anger, etc. in order to increase people's understanding of and knowledge about disaster-related issues; as a necessary step in the process of disaster risk reduction and improving safety and development. In ancient times when science was in its infancy, people believed that disasters, especially earthquakes, represented the power of Mother Nature and humans’ vulnerability and were dominated by the need to survive amid the ferocity of nature. Today, a new approach is needed in order to change the mentality of traditional communities regarding the concepts that disasters are God’s will or expressions of His wrath. It is necessary to clarify misconceptions such as those relating to fatalism and God’s will about whether individuals will be saved or sacrificed to disaster, and that mosques and holy places are immune to damage, as was believed during the past earthquakes. Disaster Risk Reduction (DRR) is defined as a combination of hazard, vulnerability of the built environment, and human socio-economic and cultural impacts, as well as in terms of a country’s level of governance, capacity, preparedness and response to catastrophic events when they occur. The "guiding principles" of DRR can be outlined as: 1) Belief in the facts of nature and existence of natural hazard of the earth; Comprehensiveness; 2) Expert leadership and good governance is essential to the success of DRR programs; 3) Risk reduction should have the objective of sustainable development, but this can only be achieved effectively through collaborative efforts devoted to promoting good management; and 4) Risk reduction requires long-term actions based on consistent policies and backed by tolerance of the slow pace of the implementation. Key Concepts of Islam which relate to the principles of risk reduction can be outlined as: 1) Submission to the will and guidance of Allah (God) based on cognition, wisdom, belief, faith and revelation, resulting in “good deeds”, vitality and happiness; 2) Human deeds and behavior should be based on belief, and belief should be complemented with good deeds; 3) Leadership of wise, elite, and intellect; 4) High value is attributed to group work, social activities, social responsibilities, co-operation and consultation in various aspects of life; 5) God’s will (Taghdir and Sonnat Elahi) is based on human deeds and behavior; 6) Human beings do not have any right to harm themselves or others and highest importance is given to respecting and observing the “Human Rights”; 7) Public Supervision (Amr-bil-Maruf); and 8) Sin means violating God’s guidance by ignoring facts and knowledge, being negligent or failing to use knowledge; etc. It can easily be seen that many of the key concepts in Islam support the guiding principles of DRR. These concepts are among the best guidance for Muslims towards good quality and safe construction and developments and as a means of stopping negligence in order to avoid seismic losses and earthquake disasters. The Holy Quran as the principal source of religious thought in Islam with its multi dimensional meanings, is also the principal source of guidance on all aspects of life and can comprehensively be adapted to all times and matters. The term “Earthquake” is mentioned directly in Chapter 99 of the Quran; and indirectly in various verses such as: 7:78, 7:91, 7:155, 7:171, 16:26, 17:37, 17:68, 29:3, 34:9, 67:16, 69:5, etc. Chapter 101, “Asr” (The Time) has special address to Belief and Good Deeds, an action required if people desire to reach success and be rewarded by being safe during natural events. It should be noted that no statement by the Prophet Mohammad (PBUH) ever mentioned that earthquakes or other disasters are expressions of the wrath of God or the result of disobedience or infidelity. Instead, there are many statements that show the need to prepare for disasters and prevent them from happening. Correlation between Islamic teaching and risk reduction principles: The Papers shows that people by following God’s guidance, can realize themselves and in religious terms, as an ultimate goal, reach heaven. In this world, 'heaven' can be interpreted a productive, safe, healthy, happy and peaceful life. According to this, “belief” and “doing good deeds” can be interpreted in most as follows: 1) Belief: believing that our Creator’s guidance is for the best of human performance and better living. People are encouraged by being given free will, awareness and knowledge to follow God’s guidance, which is comprehensive and covers all aspects of life. Believing in wisdom, facts and expertise; as well as accepting, respecting and following spiritual, individual, social and technical laws, rules and regulations. Thus, Islam and Abrahamic religion in general, encourages people to believe in earthquakes as natural phenomena and facts of the Earth and, based on this belief, encourages them to do good deeds; 2) Doing good deeds: doing the best acts possible, based on the most correct beliefs and best knowledge. In relation to earthquakes and safety, this means planning and development that are compatible with hazards; obedience to building codes and regulations; following the leadership of experts; using seismically safe construction; and, finally, using knowledge and wisdom to make the most correct use of God’s bounty and nature. In the case that people perform bad deeds and do not follow the path their punishment is destruction and loss of life, which will result in disaster. In other words, bad deeds that are carried out on the basis of ignorance or negligence and without using appropriate logic, in theological language are called 'Sin'. Thus, losses and disasters mainly result from people's bad, incorrect and inappropriate deeds. This is the simple explanation on the concepts and statements that disasters are resulted from sin. Hell, which is the result of sin, refers to a life with misery, destruction, lack of community development, and so on. Thus, disaster is not God’s wrath or his anger with regard to humanity; it is simply the result of people's bad deeds and failure to follow God’s guidance in all aspects of our lives. The discussion of the paper can be summarized as: 1) Risk communication and knowledge dissemination should be compatible with people's beliefs and cultures. I believe that the use of religious teaching and knowledge of disaster and development can be an effective way of promoting safety; and 2) Sustainable development and “Vitality” can be achieved through faith, knowledge and the conduct of good deeds. If we reject or ignore wisdom and refuse to use the know-how that God has given us as his bounty, we will do sin and face “disaster”.