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To rank the pulse-like ground motions based on the damage potential to different structures, the internal relationship between the damage potential of pulse-like ground motions and engineering demand parameters (EDPs) is analyzed in this paper. First, a total of 240 pulse-like ground motions from the NGA-West2 database and 16 intensity measures (IMs) are selected. Moreover, four reinforced concrete frame structures with significantly different natural vibration periods are established for dynamic analysis. Second, the efficiency and sufficiency of the IMs of ground motion are analyzed, and the IMs that can be used to efficiently and sufficiently evaluate the EDPs are obtained. Then, based on the calculation results, the principal component analysis (PCA) method is employed to obtain a comprehensive IM for characterizing the damage potential of pulse-like ground motions for specific building structures and EDPs. Finally, the pulse-like ground motions are ranked based on the selected IM and the comprehensive IM for four structures and three EDPs. The results imply that the proposed method can be used to efficiently and sufficiently characterize the damage potential of pulse-like ground motions for building structures.

Determination of the depth of surface-opening (visible) cracks is of critical importance for evaluating the structural safety of concrete elements. Accurately determining the crack depth wi...

Overlay systems have been extensively used to extend the service life of concrete bridge decks. There is, however, a lack of systematic studies on nondestructive evaluation (NDE) of concrete bridge decks with various overlays. This study assesses nine NDE methods for evaluation of concrete bridge decks with seven different types of overlays through laboratory concrete specimens. The nine NDE methods are sounding, ultrasonic surface waves (USW), impact echo (IE), ultrasonic testing (UT), impulse response (IR), ground-penetrating radar (GPR), electrical resistivity (ER), half-cell potential (HCP), and infrared thermography (IRT). The seven types of overlays are epoxy, latex modified concrete, silica fume modified concrete, polyester polymer, asphalt with a liquid membrane, asphalt with a sheet membrane, and asphalt without a membrane. Eight concrete specimens with various defects were built and nondestructively evaluated to acquire the detailed information of all embedded defects before placing overlays. One concrete specimen was kept bare as a reference, and the other seven specimens were covered with seven different overlays, respectively. Half of each overlay was bonded to the underlying concrete specimens, whereas the other half was debonded. NDE tests were carried out on the top of overlays. Based on the NDE test results, the applicability of each NDE method for concrete bridge decks with overlays is summarized as follows: (1) GPR and HCP are two effective methods for evaluation of the underlying concrete decks through both bonded and debonded overlays; (2) USW, IE, and UT can image the defects in the underlying concrete decks under bonded overlays, with the exception of the three asphalt overlays; (3) sounding, IR, and IRT can identify overlay debonding; and (4) ER is not effective due to electrical insulation of the overlay materials.

Nondestructive testing methods have been increasingly used to evaluate in situ layered stiffness of pavement systems. However, different testing methods could yield considerable different results, which can bring confusions and difficulties to road agencies when conducting mechanistic-based designs or setting specifications for constructions. This study compares a newly improved multichannel analysis of surface waves (MASW) method and the falling weight deflectometer (FWD) test for estimating in situ moduli of various mechanically and chemically stabilized unpaved road sections, which will serve as foundations for future surface upgrade. The comparisons showed that the trends of MASW moduli generally agree with those of the FWD test for the sections without a geosynthetic layer, but the MASW moduli are much higher than the FWD moduli for the aggregate layers. The discrepancies between the two tests were found to be greatly influenced by the different testing strain levels, which were estimated using the KENLAYER analysis. By combining the MASW and FWD moduli and calculated testing strain levels, in situ modulus reduction characteristics of the various stabilized aggregate layers can also be determined, which provides a better understanding of the in situ mechanistic performances of the different stabilization methods under different traffic loading conditions.

Aluminum alloys have found increasing use in space structures, mainly because of their high strength-to-weight ratio and satisfactory corrosion resistance. The work presented in this article is focused on finite element simulation of the failure behavior of aluminum alloy members subjected to an axial compression load and failing in overall buckling mode. The column members were fabricated by extrusion using the relatively new heat-treated aluminum alloy 6082-T6. An accurate finite element model has been developed for the simulation of aluminum alloy columns. The developed finite element model was verified against experimental results and demonstrated that it is capable of accurately predicting the deformed shapes and the ultimate loads of the tested columns. A parametric study was carried out on the stability of aluminum alloy column members failing by overall buckling. A fitting column curve was proposed for aluminum alloy design; it was somewhat more conservative than the column curve from current Chinese code GB50429.

Dynamic modulus has been recognized as an objective and sensitive material property for designing and evaluating pavement systems. To accurately measure the in situ elastic modulus ( E = 2(1 + ν) ρV s 2 ) for nondestructive quality assessment of asphalt pavements, field measurements of density ( ρ ) via an electromagnetic gauge and shear-wave velocity ( V s ) via surface-wave testing were examined for four paving projects covering a range of mixes and traffic loads. A quality control/quality assurance (QC/QA) procedure was developed to correct the in situ moduli at different field temperatures to a common reference temperature using a fitting function from experimental data for QC and using master curves from laboratory dynamic modulus tests for QA. The corrected in situ moduli can then be compared against the maximum moduli for an assessment of the actual pavement performance.

6082 is a relatively new alloy that currently provides the best combination of properties in 6xxx series alloys. A series of tests was conducted on the stability of heat-treated aluminium alloy 6082-T6 circular tube columns to check the reliability of buckling strength predictions of 6082-T6 alloy circular tube columns using current design rules. First, nine stub columns were tested to obtain stress–strain curves and three parameters of the Ramberg–Osgood expression ( E , σ 0.2 and n ). The experimental stress–strain curves were in good agreement with the Ramberg–Osgood expression, and the mean value of σ 0.2 / n obtained from the tests was close to the Steinhardt assumption. Second, prior to column tests, the initial out-of-straightness of 15 circular tubes was accurately measured. Third, these 15 tubes, with five nominal slenderness ratios varying from 20.4 to 69.6, were tested between two pinned ends under axial compression to obtain failing modes and buckling strengths. Finally, the experimental buckling strengths were compared with the buckling strengths predicted by several current aluminium structure design codes, including the American Aluminium Design Manual (AA), Australian/New Zealand Standard 1664 (AS/NZS), and Eurocode 9 (EC9), as well as the general column curve formulation proposed by Rasmussen and Rondal [13] . These comparisons shows that the AA predictions are too conservative at small slenderness ratios, the AS/NZS predictions are unsafe at large slenderness ratios, the EC9 predictions are conservative, and the Rasmussen–Rondal formulation provides the closest and generally conservative strength predictions.