In contemporary society, industrialization and rising of terrorism threats highlight the necessity and importance of structural protection against accidental and intentionally malicious blast loads. Consequences of these extreme loading events are known to be catastrophic, involving personnel injuries and fatalities, economic loss and immeasurable social disruption. These impacts are generated not only from direct explosion effects, that is, blast overpressure and primary or secondary fragments, but also from the indirect effects such as structural collapse. The latter one is known to be more critical leading to massive losses. It is therefore imperative to enlighten our structural engineers and policy regulators when designing modern structures. Towards a better protection of concrete structures, efforts have been devoted to understanding properties of construction materials and responses of structures subjected to blast loads. Reliable blast resistance design requires a comprehensive knowledge of blast ...

Review of the current practices in blast-resistant analysis and design of concrete structures:

Structural optimization using equivalent static loads at all time intervals

Structural Optimization under Equivalent Static Loads transformed from Dynamic Loads based on Displacement

Linear static response structural optimization has been developed fairly well by using the finite element method for linear static analysis. However, development is extremely slow for structural optimization where a non linear static analysis technique is required. Optimization methods using equivalent static loads (ESLs) have been proposed to solve various structural optimization disciplines. The disciplines include linear dynamic response optimization, structural optimization for multi-body dynamic systems, structural optimization for flexible multi-body dynamic systems, nonlinear static response optimization and nonlinear dynamic response optimization. The ESL is defined as the static load that generates the same displacement field by an analysis which is not linear static. An analysis that is not linear static is carried out to evaluate the displacement field. ESLs are evaluated from the displacement field, linear static response optimization is performed by using the ESLs, and the design is updated. This process proceeds in a cyclic manner. A variety of problems have been solved by the ESLs methods. In this paper, the methods are completely overviewed. Various case studies are demonstrated and future research of the methods is discussed.

Technical overview of the equivalent static loads method for non-linear static response structural optimization

Optimization of a nuclear fuel spacer grid spring using homology constraints

All the loads in the real world act dynamically on structures. Since dynamic loads are extremely difficult to handle in analysis and design, static loads are utilized with dynamic factors. The dyna mic factors are generally determined based on experiences. Therefore, the static loads can cause problems in precise analysis and design. An analytical method based on modal analysis has been proposed for the transformation of dynamic loads into equivalent static load sets. Equivalent static load sets are calculated to generate an identical displacement field in a structure with that from dynamic loads at a certain time. The process is derived and evaluated mathematically. The method is verified through numerical tests. Various characteristics are identified to match the dynamic and the static behaviors. For example, the opposite direction of a dynamic load should be considered due to the vibration response. A dynamic bad is transformed to multiple equivalent static loads according to the number of the critical times. The places of the equivalent static load can be different from those of the dynamic load. An optimization method is defined to use the equivalent static loads. The developed optimization process has the same effect as the dynamic optimization which uses the dynamic loads directly. Standard examples are solved and the results are discussed

Structural Optimization under Equivalent Static Loads Transformed from Dynamic Loads Based on Displacement

The usage of a beam scanning type laser marker is rapidly increasing in the field of semiconductor equipment. A device called a “beam adjuster” is employed to adjust the visible diode laser, which points to the marking position for various settings. The device is very sensitive to manufacturing tolerances and assembling conditions. The axiomatic approach is applied to the design of the device. An existing design is analyzed based on the Independence Axiom, but the existing design is discovered to violate the axiom. Two new designs are proposed to satisfy the Independence Axiom. The Information Axiom is utilized to evaluate the designs, and the selected design has minimum information content. The significance of this research is that a full cycle of axiomatic design is applied to a real engineering product.

Axiomatic Design of a Beam Adjuster for Laser Marker

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Robust Design of the Vibratory Gyroscope with Unbalanced Inner Torsion Gimbal Using Axiomatic Design

Generally, dynamic loads are applied to real structures. Since the analysis with the dynamic load is extremely difficult, static loads are utilized by proper conversions of the dynamic loads. The dynamic loads are usually converted ot static loads by safety foactors of experiences. However, it may increase weight and decrease reliability. In this study, a method is proposed for the conversion process. An equivalent static load is calculated ot generate a same maximum displacement. The method is verified through numerical tests on a spring-mass systems of one and multi degrees-of freedom. It has been found that the duration time of the loads and the natural frequencies of the structures are critical in the conversion process. A road arem is a self-propelled howizer is selected for the application of the proposed method. The shape of the road arm is optimized under the converted static loads.

Transformation of a Dynamic Load into an Equivalent Static Load and Shape Optimization of the Road Arm in Self-Propelled Howitzer

The structural optimization have been carried out in the continuous design space or in the discrete design space. Methods fur discrete variables such as genetic algorithms , are extremely expensive in computational cost. In this research, an iterative optimization algorithm using orthogonal arrays is developed for design in discrete space. An orthogonal array is selected on a discrete des inn space and levels are selected from candidate values. Matrix experiments with the orthogonal array are conducted. New results of matrix experiments are obtained with penalty functions leer constraints. A new design is determined from analysis of means(ANOM). An orthogonal array is defined around the new values and matrix experiments are conducted. The final optimum design is found from iterative process. The suggested algorithm has been applied to various problems such as truss and frame type structures. The results are compared with those from a genetic algorithm and discussed.

Gyeong-Jin Park

Papers

Structural Optimization under Equivalent Static Loads Transformed from Dynamic Loads Based on Displacement

Axiomatic Design of a Beam Adjuster for Laser Marker

Robust Design of the Vibratory Gyroscope with Unbalanced Inner Torsion Gimbal Using Axiomatic Design

Transformation of a Dynamic Load into an Equivalent Static Load and Shape Optimization of the Road Arm in Self-Propelled Howitzer

Development of an Optimization Algorithm Using Orthogonal Arrays in Discrete Design Space