Optical fiber sensor (OFS) technologies have developed rapidly over the last few decades, and various types of OFS have found practical applications in the field of civil engineering. In this paper, which is resulting from the work of the RILEM technical committee "Optical fiber sensors for civil engineering applications'', different kinds of sensing techniques, including change of light intensity, interferometry, fiber Bragg grating, adsorption measurement and distributed sensing, are briefly reviewed to introduce the basic sensing principles. Then, the applications of OFS in highway structures, building structures, geotechnical structures, pipelines as well as cables monitoring are described, with focus on sensor design, installation technique and sensor performance. It is believed that the State-ofthe-Art review is helpful to engineers considering the use of OFS in their projects, and can facilitate the wider application of OFS technologies in construction industry.

The relation between the component strain and the strain on a surface-attached optical fiber is governed by the effectiveness of shear transfer through the adhesive and the polymeric coating(s) on the optical fiber. A classical shear lag model can predict the strain transfer through a soft layer well. However, experiments showed that the results are unsatisfactory for bare fiber with stiff adhesive case. A 3D-FEM is established to model the strain transfer of a surface-mounted strain sensor and it is verified by experiments. Then, it is used to investigate the influence of four geometric parameters of the adhesive: (1) side width, (2) top thickness, (3) bond length, (4) bottom thickness, on the strain transfer. By sensitivity analysis, it is revealed that the bond length and the bottom thickness are dominant factors. Based on finite element results, the parameter of the analytical model is modified to suit stiff layer cases. Important considerations for practical installation of surface-attached optical interferometric and FBG strain sensors will be discussed.

Reactions of HCtCCH 2 CH(OR)CH(OR)CH 2 CtCH (R ) H, MeSO 2 ) with RuHCl(CO)(PPh 3 ) 3 produced [RuCl(CO)(PPh 3 ) 2 ] 2 (µ-CHdCHCH 2 CH(OR)CH(OR)CH 2 CHdCH), which on treatment with PMe 3 gave [RuCl(CO)(PMe 3 ) 3 ] 2 (µ-CHdCHCH 2 CH(OR)CH(OR)CH 2 CHdCH). Treatment of RuHCl(CO)(PPh 3 ) 3 with (3E,5E)-HCtCCHdCHCHdCHCtCH produced [RuCl-(CO)(PPh 3 ) 2 ] 2 (µ-CHdCHCHdCHCHdCHCHdCH). The later complex reacted with PMe 3 , 4-phenylpyridine (PhPy), and 2,6-(Ph 2 PCH 2 ) 2 C 5 H 3 N (PMP) to give [RuCl(CO)(PMe 3 ) 3 ] 2 (µ-CHdCHCHdCHCHdCHCHdCH), [RuCl(CO)(PhPy)(PPh 3 ) 2 ] 2 (µ-CHdCHCHdCHCHdCHCHd CH), and [RuCl(CO)(PMP)] 2 (µ-CHdCHCHdCHCHdCHCHdCH), respectively. The struc-turesofRuCl(CO)(PMe 3 ) 3 ] 2 (µ-CHdCHCH 2 CH(OH)CH(OH)CH 2 CHdCH)and[RuCl(CO)(PMe 3 ) 3 ] 2 -(µ-CHdCHCHdCHCHdCHCHdCH) have been confirmed by X-ray diffraction. Bond Distances (Å)

Steel corrosion resulting from the penetration of chloride ions or carbon dioxide is a major cause of degradation for reinforced concrete structures,. The objective of the present investigation was to develop a low-cost sensor for steel corrosion, which is based on a very simple physical principle. The flat end of a cut optical fiber is coated with an iron thin film using the ion sputtering technique. Light is then sent into a fiber embedded in concrete and the reflected signal is monitored. Initially, most of the light is reflected by the iron layer. When corrosion occurs to remove the iron layer, a significant portion of the light power will leave the fiber at its exposed end, and the reflected power is greatly reduced. Monitoring of the reflected signal is hence an effective way to assess if the concrete environment at the location of the fiber tip may induce steel corrosion or not. In this paper, first the principle of the corrosion sensor and its fabrication are described. The sensing principle is then verified by experimental results. Sensor packaging for practical installation will be presented and the performance of the packaged sensors is assessed by additional experiments.

No abstract

No abstract

A foamed alkali-activated material (FAAM) based on tungsten mining waste (TMW) and municipal waste glass (WG) is fabricated by using aluminum powder and organic surfactant foaming agents. The compressive strength and density of the FAAM are investigated in terms of different parameters of production and formulation, including curing temperature as well as the dosage of Na 2 O, foaming agent, foam catalyzing agent, and stabilizing agent. FAAM made with aluminum powder consists of smaller open macropores and exhibits higher compressive strength compared with FAAMs with larger closed macropores obtained by organic surfactant counterparts. The final aluminum powder-based FAAM reaches a 7-day compressive strength in excess of 3 MPa and a density below 0.7 g=cm 3. The implementation of an appropriate amount of foam stabilizer leads to a further 15% increase in compressive strength, 6% reduction in density, and a thermal conductivity below 0.1 W=mK. The FAAM explored in this study represents an ideal material for building envelope insulation.

Abstract-Optical fibre strain sensors, especially the fibre Bragg grating (FBG) type, are widely applied in different applications. The most common installation method is surface-attached. In principle, optical fibre strain sensor with adequate sampling and signal processing techniques is usually more accurate than electrical resistive strain gauge. However, the strain of the surface of structure may not transfer to the sensing element perfectly. The ratio between the measured and actual strain can be correlated by a strain transfer factor (STF). However, it depends on the material and geometrical properties of the optical fibre and adhesive. It is non-economical and impractical to measure STF for every installed sensor. It is desirable to identify the most sensitive parameters on the variation of STF so that the quality control and assurance procedure can be performed more efficiently. In this paper, a quantitative global sensitivity analysis, called extended Fourier amplitude sensitivity test will be performed to compute the first-order and total sensitivity indexes based on a well-established semi-analytical/empirical mechanical model of three material and five geometrical parameters of both integral and OFBG type optical fibre strain sensor with two different kinds of polymeric coating under three types of strain field in sixteen different configurations. From the detail analysis, the most sensitive parameters on STF are bond length, the thickness of adhesive beneath the optical fibre and the deviation of grating position, which are related to workmanship instead of the material properties of optical fibre and adhesive.Index Terms-optical fibre strain sensor, strain transfer, extended Fourier amplitude sensitivity test, global sensitivity analysis.