This paper presents an efficient numerical methodology in probabilistically solving the governing partial differential equation of solid mechanics with uncertainties in both the material parameter and forcing function in the time domain using the stochastic Galerkin approach. The methodology hypothesizes the input forcing function and the elastic modulus of the solid to be a nonstationary random process and a heterogeneous random field, respectively, and efficiently represents them in terms of multidimensional Hermite polynomial chaos -orthogonal and uncorrelated polynomials of zero-mean, unit variance Gaussian random variables -by taking advantage of the optimality of the Kosambi-Karhunen-Loève theorem. The methodology allows for any non-Gaussian marginal distributions and any arbitrary correlation structures for the input process and field. The solution random processes (displacement, velocity, and acceleration) are also represented in
Research was conducted to investigate how the inclination angle of the diagonal tension field action varies in steel plate shear walls (SPSWs) and to determine what optimum constant angle best matches the demands obtained from finite-element (FE) analysis. An FE model was first calibrated against experimental results that surveyed inclination angles across the web plate of an idealized SPSW as a function of drift and that showed significant differences in inclination angles at different locations across the web plate. Then, four real SPSWs with varying aspect ratios and numbers of stories were designed and modeled for FE analyses. The variations in angle in the web plate and along the boundary elements were documented as a function of drift and showed significant variations. Combined moment-axial force demand ratios in the SPSW boundary elements were calculated and compared for all real SPSWs to determine the preferable value of single angle that could be used in design. Overall, using 45°was found to be a reasonable compromise for both horizontal and vertical boundary element (HBE and VBE, respectively) design if a single constant angle is desired. Furthermore, the demand on the web plate is not sensitive to the variation of inclination angle. Consequently, the single angle of 45°is recommended for the design of the entire SPSW.
Summary
This paper introduces a new and unique full‐scale testbed site for structural health monitoring and soil–structure system identification studies being developed in southwest China. The site is a 48‐story skyscraper with an extended four‐level basement, supported by piles, located in Kunming, the capital of Yunnan Province. Located in the diffused zone of collision of the Indian and Eurasian tectonic plates, Yunnan is one of the most active seismic areas in mainland China. The final sensor deployment will consist of 43 triaxial accelerometers (129 channels) and one weather station. The accelerometer array comprises (a) a structural array of 25 accelerometers installed at 10 levels aboveground, (b) a basement array of 14 accelerometers distributed in the first and fourth basements, and (c) two borehole arrays installed close to the basement perimeter wall, each with one accelerometers at the surface and another one at 50‐m depth, which is the depth reached by the piles. With such dense instrumentation of structure, basement, and pile foundation, this site will be the first permanently instrumented full‐scale testbed to enable identification of a soil‐foundation–basement‐structure system and validation of many assumptions commonly made in the prediction of the soil–structure interaction effects. A high‐performance wired local area network has been installed in the building, featuring a Precision Time Protocol‐enabled time synchronization and real‐time remote access over the Internet. The site will be fully operational in late spring of 2020. Results of preliminary system identification of the structure from ambient vibration test data are presented.
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