Structural optimization has progressed substantially over the last half century. However, the literature on optimization of structures under random excitation is limited. This study provides a framework for structural optimization subject to stochastic dynamic loading. Illustrative examples of structures under nonstationary seismic and stationary wind loads are presented to demonstrate the procedure. Both safety and serviceability are considered concurrently. The objective function for safety is given in terms of both harmful interstory drift and harmful interstory drift angle; whereas for serviceability, the objective function is defined in terms of floor acceleration. Safety and serviceability are shown to be competing objectives under both seismic and wind excitation; however, the contrast is less under wind excitation. The proposed optimization framework provides a rational manner in which engineering design tradeoffs can be made between the two competing objectives.

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The 4th industrial revolution started in 2016 and referred to a new phase in the industrial revolution. One of the most significant technological evolvements during the 4th industrial revolution is Augmented Reality (AR) technology. AR superimposes interactional virtual objects/images to real environments. Because of the interaction and see-through characteristics, AR is better applied to engineering than Virtual Reality (VR). The application of AR in civil infrastructure can avoid artificial mistakes, improve efficiency, and saves budget. This article reviews AR applications in civil infrastructure, focusing on research studies in the latest five years (2016–2020) and their milestone developments. More than half of the AR research and implementation studies have focused on the construction domain in the last five years. Researchers deploy AR technologies in on-site construction to assist in discrepancy checking, collaborative communication, and safety checking. AR also uses building information models (BIMs) to produce detailed 3D structural information for visualization. Additionally, AR has been studied for structural health monitoring (SHM), routine and damage detection, energy performance assessment, crack inspection, excavation, and underground utility maintenance. Finally, AR has also been applied for architecture design, city plan, and disaster prediction as an essential part of smart city service. This article discusses the challenges of AR implementation in civil infrastructure and recommends future applications.

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