Cracks in concrete structures can be indicators of important damage and may significantly affect durability. Their timely identification can be used to ensure structural safety and guide on-time maintenance operations. Structural health monitoring solutions, such as strain gauges and fiber optics systems, have been proposed for the automatic monitoring of such cracks. However, these solutions become economically difficult to deploy when the surface under investigation is very large. This paper proposes to leverage a novel sensing skin for monitoring cracks in concrete structures. This sensing skin is constituted of a flexible electronic termed soft elastomeric capacitor, which detects a change in strain through changes in measured capacitance. The SEC is a low-cost, durable, and robust sensing technology that has previously been studied for the monitoring of fatigue cracks in steel components. In this study, the sensing skin is introduced and preliminary validation results on a small-scale reinforced concrete beam are presented. The technology is verified on a full-scale post-tensioned concrete beam. Results show that the sensing skin is capable of detecting, localizing, and quantifying cracks that formed in both the reinforced and post-tensioned concrete specimens.

In a deck-on-girder composite beam system, the deck and supporting girders work together to effectively provide loading capacity. This system has been widely used for bridges, buildings, and other structures. Effective flange width is typically used to reduce a three-dimensional behavior of the composite beam system to the analysis of a T-beam section with a reduced width of deck. Current studies, including AASHTO specifications, are mainly focused on concrete decks with full-composite action. This paper presents a closed-form solution to study the composite beam system, which considers different degrees of composite action (DCAs) between the deck and supporting girders and can be applied to decks with orthotropic materials. The analytical model is verified through close correlations among test, finite-element, and analytical results for two T-beams with concrete and fiber-reinforced polymer (FRP) decks, in terms of both deflections and stress distributions. A parametric study is then conducted by...

In the past two decades, fiber-reinforced polymer (FRP) materials have been increasingly used in civil engineering. Compared with its wide applications in the civil infrastructure system, the use of FRP in buildings is rather limited. One reason for this is that, unlike civil infrastructure, buildings have more stringent nonstructural performance requirements, including those for fire rating, smoke and toxicity, flame spread, water resistance, flood resistance, and so forth. Although numerous studies have been conducted on structural performances of FRP structures, limited studies are available on the nonstructural performance. This paper aims to identify the gap between building code requirements and the current state of research on FRP materials. The first section of this paper is devoted to a summary of the research findings on nonstructural performances. Based on codes and other specifications, the second section systematically examines the code requirements according to the FRP’s target applications, such as load bearing members, interior finishes, exterior finishes, or roofings, and their corresponding standards. The next section evaluates the research findings from the first section against the requirements from building codes in the second section. Finally, the applicability, limitations, and future work for FRP materials to be used for building applications are provided in the last section. It can be concluded that, strengthwise, FRP can be used for building applications. Fire rating can be met with different insulate schemes, which vary from 0 to 3 h based on different applications. Exposed FRP needs to meet the requirements of smoke, toxicity, and flame spread. Adding fire-retardant fillers, such as alumina trihydrate (ATH), can enhance performances and meet the code requirements. Further studies on water resistance, weathering tests, flood resistance, combustion, and so forth, are needed. Most of the insulation materials are proprietary and expensive, which restricts their wider applications. It is advantageous to develop cost-effective fire protection systems. No study is available on unified modeling and design guidelines for fire rating, smoke, toxicity, and flame spread. There is a need to provide effective design methods to design these items based on their targeted applications, similar to the methods for structural design.

In bridge engineering, the three-dimensional behavior of a bridge system is usually reduced to the analysis of a T-beam section, loaded by an equivalent fraction of the applied live load, which is called the live load distribution factor (LDF). The LDF is defined in the both the AASHTO Standard Specifications and the LRFD Specifications primarily for concrete slabs and has inherent applicable limitations. This paper provides explicit formulas using series solutions for LDF of orthotropic bridge decks, applicable to various materials but intended for fiber-reinforced polymer (FRP) decks. The present formulation considers important parameters that represent the response characteristics of the structure that are often omitted or limited in the AASHTO Specifications. A one-term series solution is proposed based on the macroflexibility approach, in which the bridge system is simplified into two major components, deck and stringers. The governing equations for the two components are obtained separately, and the...