Vibration-based damage detection (VBDD) comprises a promising set of techniques for damage detection and health monitoring of civil engineering structures. However, the successful application of these methods to real structures is still a challenging task, due primarily to the large size of such structures and the relatively high levels of variability in their dynamic response under operational load conditions. In this paper, a new methodology is introduced for the application of VBDD techniques, with the goal of enhancing their effectiveness for identifying and locating low damage levels and improving their applicability to the continuous or periodic health monitoring of structures. The basic features of the methodology include the use of a controlled and consistent excitation force, the use of operational deflection shapes (ODSs) at all measured frequency increments rather than only at natural frequencies, the use of a logarithmic scale for representing the ODS amplitudes at each frequency increment and the establishment of a threshold level for damage detection that accounts for experimental variability. The performance of the proposed methodology is verified and demonstrated by applying several Level 1 (damage detection) and Level 2 (damage localization) VBDD techniques using experimental data measured on a steel girder taken from a railway bridge. The proposed approach is shown to perform very well at detecting, locating and monitoring the growth of damage. Copyright © 2011 John Wiley & Sons, Ltd.

This paper presents new experimental techniques utilizing a smart debris device for direct measurement of the impact acceleration forces associated with tsunami-borne debris that impact inland structures. The resulting experimental data will lead to advanced predictive capabilities of such forces for use in design guidelines. The measured debris acceleration data were used to calculate impact forces (mass × acceleration). An image processing technique was used to detect the debris impact angle. The debris impact tests were conducted using a disc-shaped smart debris device with masses of 550, 800 and 1000 g. For calculation of the debris force it was found necessary to include the mass of entrained water. The impact acceleration was found to be a function of debris mass, velocity, and contact duration. An equation is developed to allow estimation of the debris velocity for a known distance between the debris pick-up location by a tsunami and the structure.

One-part alkali-activated materials (AAMs) are developed to improve conventional two-part systems. One-part AAMs technology has been used in cement binders to produce concrete, mortar, and paste. Current research mainly focuses on synthesizing raw materials obtained from industrial and agricultural waste as the main aluminosilicate precursors of the cement binder for a concrete application. The one-part AAMs were reported to have higher early compressive strength at 7 days of age, contributed by its fast-setting time, mainly when the binder activates by a higher dosage of alkaline activator and containing OPC-rich. Due to bonding issues, single or combination, FA/GGBFS/MK precursors were reported as unsuitable for use as a concrete repair material. They were the reason for the lack of one-part AAMs application of mortar compared to concrete usage. This study was conducted to determine the potential of one-part AAMs used as concrete patch mortar by investigating its rheology and mechanical properties. The compressive strength of the mortar was tested under lab ambient temperature in the tropical climate country of Malaysia. The setting time of fresh mortar and bonding strength were set under controlled lab temperature. The one-part alkali-activated mortar was composed of hybrid aluminosilicate precursors between fly ash (FA), Ground Granulated Blast Furnace Slag (GGBFS) and ordinary Portland cement (OPC). A low alkaline activator of solid potassium carbonate was used for the geopolymerization process. Three types of solid admixtures were added to complete the composition of the new mix design. The experiment's outcome showed that the mortar composed with the combination of conventional Portland cement and industrial waste products has compressive and pull-off adherence strength that meets with Class R3—EN1504-3 standard for structural concrete repair materials requirement.