It is with great pleasure that I accepted invitation of Adnan Ibrahimbegovic to write this preface, for this invitation gave me the privilege to be one of the ?rsttoreadhisbookandallowedmetoonceagainemphasizetheimportance for our discipline of solid mechanics, which is currently under considerable development, to produce the reference books suitable for students and all other researchers and engineers who wish to advance their knowledge on the subject. Thesolidmechanicshascloselyfollowedtheprogressincomputerscienceand is currently undergoing a true revolution where the numerical modelling and simulations are playing the central role. In the industrial environment, the 'virtual' (or the computing science) is present everywhere in the design and engineering procedures. I have a habit of saying that the solid mechanics has become the science of modelling and inthat respectexpanded beyondits t- ditional frontiers. Several facets of current developments have already been treated in di?erent works published within the series 'Studies in mechanics of materials and structures'; for example, modelling heterogeneous materials (Besson et al. ), fracture mechanics (Leblond), computational strategies and namely LATIN method (Ladev' eze), instability problems (NQ Son) and ve- ?cation of ?nite element method (Ladev' eze-Pelle). To these (French) books, one should also add the work of Lemaitre-Chaboche on nonlinear behavior of solid materials and of Batoz on ?nite element method.

This volume contains the best papers presented at the 2nd ECCOMAS International Conference on Multiscale Computations for Solids and Fluids, held June 10-12, 2015. Topics dealt with include multiscale strategy for efficient development of scientific software for large-scale computations, coupled probability-nonlinear-mechanics problems and solution methods, and modern mathematical and computational setting for multi-phase flows and fluid-structure interaction. The papers consist of contributions by six experts who taught short courses prior to the conference, along with several selected articles from other participants dealing with complementary issues, covering both solid mechanics and applied mathematics.

1.1. SAFETY OF CIVIL STRUCTURES Society expects that the failure of civil structures is extremely rare and relies on the care and expertise of the professionals involved in the design, construction and maintenance of structures. This is in particular true for public technical systems such as transportation or energy supply systems and structures such as bridges. Structural safety may be defined as follows: "Adequate safety with respect to a hazard is ensured provided that the hazard is kept under control by appropriate measures or the risk is limited to an acceptable value. Absolute safety is not achievable." It is thus not the structure as such that is designated safe but rather the people, goods and the environment in its surroundings. The continued use of existing structures is of great importance because the built environment is a huge economic and political asset, growing larger every year. Nowadays evaluation of the safety of existing structures is a major engineering task, and structural engineers are increasingly called upon to devise ways for extending the life of structures whilst observing tight cost constraints. Also, existing structures are expected to resist against accidental actions although they were not designed for. Engineers may apply specific methods for evaluation in order to preserve structures and to reduce a client's expenditure. The ultimate goal is to limit construction intervention to a minimum, a goal that is clearly in agreement with the principles of sustainable development.

The effect of combined extreme transient loadings on a structure is not well understood-whether the source is man-made, such as an explosion and fire, or natural, such as an earthquake or extreme wind loading. A critical assessment of current knowledge is timely (with Fukushima-like disasters or terrorist threats). The central issue in all these problems is structural integrity, along with their transient nature, their unexpectedness, and often the uncertainty behind their cause. No single traditional scientific discipline provides complete answers, rather, a number of tools need to be brought together: nonlinear dynamics, probability theory, some understanding of the physical nature of the problem, as well as modeling and computational techniques for representing inelastic behavior mechanisms. Nonlinear Dynamics of Structures Under Extreme Transient Loads covers model building for different engineering structures and provides detailed presentations of extreme loading conditions. A number of illustrations are given quantifying; a plane crash or explosion induced impact loading, the effects of strong earthquake motion, and the impact and long-duration effects of strong stormy winds-along with a relevant framework for using modern computational tools. The book considers the levels of reserve in existing structures, and ways of reducing the negative impact of high-risk situations by employing sounder design procedures.

The book provides a critical assessment of the current knowledge and indicates new challenges which are brought about by the present times in fighting man-made and natural hazards in transient analysis of structures. The latter concerns both permanently fixed structures, such as those built to protect people and/or sensitive storage material (e.g. military installations) or special structures in transportation systems (e.g. bridges, tunnels), and moving structures (such as trains, planes, ships or cars). The present threat of terrorist attacks or accidental explosions, the climate change which brings strong stormy winds or even the destructive earthquake motion that occurs in previously inactive regions or brings about tsunamis, are a few examples of the kind of applications addressed in this work.

Problems of such diversity cannot be placed within a single traditional scientific discipline, but call for the expertise in probability theory for quantifying the cause, interaction problems for better understanding the physical nature of the problems, as well as modeling and computational techniques for improving the representation of inelastic behavior mechanisms and providing the optimal design.

It is with great pleasure that I accepted invitation of Adnan Ibrahimbegovic to write this preface, for this invitation gave me the privilege to be one of the ?rsttoreadhisbookandallowedmetoonceagainemphasizetheimportance for our discipline of solid mechanics, which is currently under considerable development, to produce the reference books suitable for students and all other researchers and engineers who wish to advance their knowledge on the subject. Thesolidmechanicshascloselyfollowedtheprogressincomputerscienceand is currently undergoing a true revolution where the numerical modelling and simulations are playing the central role. In the industrial environment, the 'virtual' (or the computing science) is present everywhere in the design and engineering procedures. I have a habit of saying that the solid mechanics has become the science of modelling and inthat respectexpanded beyondits t- ditional frontiers. Several facets of current developments have already been treated in di?erent works published within the series 'Studies in mechanics of materials and structures'; for example, modelling heterogeneous materials (Besson et al. ), fracture mechanics (Leblond), computational strategies and namely LATIN method (Ladev' eze), instability problems (NQ Son) and ve- ?cation of ?nite element method (Ladev' eze-Pelle). To these (French) books, one should also add the work of Lemaitre-Chaboche on nonlinear behavior of solid materials and of Batoz on ?nite element method.

1.1. SAFETY OF CIVIL STRUCTURES Society expects that the failure of civil structures is extremely rare and relies on the care and expertise of the professionals involved in the design, construction and maintenance of structures. This is in particular true for public technical systems such as transportation or energy supply systems and structures such as bridges. Structural safety may be defined as follows: "Adequate safety with respect to a hazard is ensured provided that the hazard is kept under control by appropriate measures or the risk is limited to an acceptable value. Absolute safety is not achievable." It is thus not the structure as such that is designated safe but rather the people, goods and the environment in its surroundings. The continued use of existing structures is of great importance because the built environment is a huge economic and political asset, growing larger every year. Nowadays evaluation of the safety of existing structures is a major engineering task, and structural engineers are increasingly called upon to devise ways for extending the life of structures whilst observing tight cost constraints. Also, existing structures are expected to resist against accidental actions although they were not designed for. Engineers may apply specific methods for evaluation in order to preserve structures and to reduce a client's expenditure. The ultimate goal is to limit construction intervention to a minimum, a goal that is clearly in agreement with the principles of sustainable development.

The effect of combined extreme transient loadings on a structure is not well understood-whether the source is man-made, such as an explosion and fire, or natural, such as an earthquake or extreme wind loading. A critical assessment of current knowledge is timely (with Fukushima-like disasters or terrorist threats). The central issue in all these problems is structural integrity, along with their transient nature, their unexpectedness, and often the uncertainty behind their cause. No single traditional scientific discipline provides complete answers, rather, a number of tools need to be brought together: nonlinear dynamics, probability theory, some understanding of the physical nature of the problem, as well as modeling and computational techniques for representing inelastic behavior mechanisms. Nonlinear Dynamics of Structures Under Extreme Transient Loads covers model building for different engineering structures and provides detailed presentations of extreme loading conditions. A number of illustrations are given quantifying; a plane crash or explosion induced impact loading, the effects of strong earthquake motion, and the impact and long-duration effects of strong stormy winds-along with a relevant framework for using modern computational tools. The book considers the levels of reserve in existing structures, and ways of reducing the negative impact of high-risk situations by employing sounder design procedures.

This volume contains the best papers presented at the 2nd ECCOMAS International Conference on Multiscale Computations for Solids and Fluids, held June 10-12, 2015. Topics dealt with include multiscale strategy for efficient development of scientific software for large-scale computations, coupled probability-nonlinear-mechanics problems and solution methods, and modern mathematical and computational setting for multi-phase flows and fluid-structure interaction. The papers consist of contributions by six experts who taught short courses prior to the conference, along with several selected articles from other participants dealing with complementary issues, covering both solid mechanics and applied mathematics.

The book provides a critical assessment of the current knowledge and indicates new challenges which are brought about at present times by fighting man-made and natural hazards in transient analysis of structures. The latter concerns both permanently fixed structures, such as those built to protect people and/or sensitive storage material (e.g. military installations) or special structures found in transportation systems (e.g. bridges, tunnels), and moving structures (such as trains, planes, ships or cars). The present threat of terrorist attacks or accidental explosions, the climate change which brings strong stormy winds or even the destructive earthquake motion that occurs in previously inactive regions or brings about tsunamis, are a few examples of the kind of applications addressed in this work.

Problems of such diversity cannot be placed within a single traditional scientific discipline, but call for the expertise in probability theory for quantifying the cause, interaction problems for better understanding the physical nature of the problems, as well as modeling and computational techniques for improving the representation of inelastic behavior mechanisms and providing the optimal design.