Structural Identification of an 18-Story RC Building in Nepal Using Post-Earthquake Ambient Vibration and Lidar Data

Few studies have been conducted to systematically assess post-earthquake condition of structures using vibration measurements. This paper presents system identification and finite element (FE) modeling of an 18-story apartment building that was damaged during the 2015 Gorkha earthquake and its aftershocks in Nepal. In June 2015, a few months after the earthquake, the authors visited the building and recorded the building’s ambient acceleration response. The recorded data are analyzed, and the modal parameters of the structure are identified using an output-only system identification method. A linear FE model of the building is also developed to estimate numerically its dynamic properties. The identified modal parameters are compared to those of the model to identify possible shortcomings of the modeling and identification approaches. The identified natural frequencies and mode shapes for two of the three closely spaced vibration modes in the lower frequency range of interest (0.2–1.0 Hz) are in good agreement with the numerical model. The model is used to estimate the response of the building to the nearby recorded ground motion due to earthquake and the main aftershock. The maximum drift ratios are compared to the observed damage in the building and surface defects detected and quantified by the lidar scans as the research team performed a series of light detection and ranging (lidar) scans from interior of selected floors to document the damage patterns along the height of the building

Observations About the Seismic Response of RC Buildings in Mexico City

Over 2000 buildings were surveyed by members of the Colegio de Ingenieros (CICM) and Sociedad Mexicana de Ingenieria Estructural (SMIE) in Mexico City following the Puebla-Morelos Earthquake of 2017. This inventory of surveyed buildings included nearly 40 collapses and over 600 buildings deemed to have structural damage. Correlation of damage with peak ground acceleration (PGA), peak ground velocity (PGV), predominant spectral period, building location, and building properties including height, estimated stiffness, and presence of walls or retrofits was investigated for the surveyed buildings. The evidence available suggests that (1) ground motion intensity (PGV) drove the occurrence of damage and (2) buildings with more infill and stiff retrofit systems did better than other buildings

Effect of surgical experience and spine subspecialty on the reliability of the {AO} Spine Upper Cervical Injury Classification System

OBJECTIVE The objective of this paper was to determine the interobserver reliability and intraobserver reproducibility of the AO Spine Upper Cervical Injury Classification System based on surgeon experience (< 5 years, 5–10 years, 10–20 years, and > 20 years) and surgical subspecialty (orthopedic spine surgery, neurosurgery, and "other" surgery). METHODS A total of 11,601 assessments of upper cervical spine injuries were evaluated based on the AO Spine Upper Cervical Injury Classification System. Reliability and reproducibility scores were obtained twice, with a 3-week time interval. Descriptive statistics were utilized to examine the percentage of accurately classified injuries, and Pearson’s chi-square or Fisher’s exact test was used to screen for potentially relevant differences between study participants. Kappa coefficients (κ) determined the interobserver reliability and intraobserver reproducibility. RESULTS The intraobserver reproducibility was substantial for surgeon experience level (< 5 years: 0.74 vs 5–10 years: 0.69 vs 10–20 years: 0.69 vs > 20 years: 0.70) and surgical subspecialty (orthopedic spine: 0.71 vs neurosurgery: 0.69 vs other: 0.68). Furthermore, the interobserver reliability was substantial for all surgical experience groups on assessment 1 (< 5 years: 0.67 vs 5–10 years: 0.62 vs 10–20 years: 0.61 vs > 20 years: 0.62), and only surgeons with > 20 years of experience did not have substantial reliability on assessment 2 (< 5 years: 0.62 vs 5–10 years: 0.61 vs 10–20 years: 0.61 vs > 20 years: 0.59). Orthopedic spine surgeons and neurosurgeons had substantial intraobserver reproducibility on both assessment 1 (0.64 vs 0.63) and assessment 2 (0.62 vs 0.63), while other surgeons had moderate reliability on assessment 1 (0.43) and fair reliability on assessment 2 (0.36). CONCLUSIONS The international reliability and reproducibility scores for the AO Spine Upper Cervical Injury Classification System demonstrated substantial intraobserver reproducibility and interobserver reliability regardless of surgical experience and spine subspecialty. These results support the global application of this classification system

Analytical and experimental study of seismic performance of reinforced concrete frames infilled with masonry walls

Unreinforced masonry panels are often used as interior or exterior partitions in reinforced concrete frames. How infills affect the seismic performance of an RC building is an intricate issue since their exact role in the seismic load resistance is not yet clearly understood due to the interaction with the bounding frame. Assessing this role presents a challenge for structural engineers due to the variety and complexity of observed failure mechanisms and the lack of reliable methods able to capture these mechanisms. Furthermore, there is a lack of experimental data from large-scale dynamic tests of multi-story, multi- bay infilled frames to validate the analytical tools. This dissertation addresses this intricate issue with extensive analytical and experimental studies. The testing program involved quasistatic tests of small and large-scale specimens with and without openings and shake-table tests of a large-scale, three-story, two-bay, RC frame. This frame, which had a non-ductile design and was infilled with unreinforced masonry panels with openings, was the largest structure of this type tested on a shake table. The design of the specimens, the testing procedures, and the obtained results are discussed in this dissertation as they enhanced the understanding of the structural behavior. The experimental data has been used to validate the proposed analytical tools. These include a nonlinear finite element methodology and a simplified assessment tool for the engineering practice. The finite element modeling methodology combines the smeared and discrete crack approaches to capture the shear and flexural failure of RC members, crushing and splitting of brick units and the mixed-mode fracture of mortar joints. A systematic approach has been developed to calibrate the material parameters, and the comparison with the experimental results indicates it can successfully capture the nonlinear behavior of the physical specimens. The validated models have been used in parametric studies to identify the critical material parameters and assess the influence of design parameters and variations of the geometrical configurations to the structural response. The parametric studies and experimental findings have been used to develop a simplified method for the structural assessment of infilled frames. The proposed approach can estimate the structural performance, including the stiffness and strength and can be used for the construction of simple strut models for an entire structur

Framväxten av intellligent systemutveckling

Med den ökande användningen av digitala system i dagens samhälle blir framstegen inom AI-området alltmer uppenbara. Modeller för språkbehandling har utvecklats till en punkt där vem som helst med internetanslutning kan ställa frågor för att snabbt få svar. Inom mjukvaruutveckling förblir problemlösning en central uppgift för utvecklare, och snabb återkoppling visar sig vara särskilt värdefull i projektbaserade arbetsmiljöer med tidsbegränsningar. Genom en kvalitativ metod baserad på semistrukturerade intervjuer undersökte denna studie användningen av AI-verktyg inom mjukvaruutveckling, och utforskade den framtida rollen för mjukvaruutvecklare i en arbetsmiljö där AI har potential att kraftigt förändra arbetsmetoder. Denna studie föreslår att AI-verktyg kommer fortsätta ge utvecklare värdefullt stöd i form av innovativ, lösningssökande återkoppling samt ersätta repetitiva uppgifter. Studiens resultat avslöjar däremot en uttryckt oro för anpassning till AI-verktyg, och hur dessa bör anpassas för att fungera inom organisationen. Tillgången till AI medför potentiella förändringar i systemutvecklingsprocesser, och om dessa inte beaktas kan utvecklare och organisationer gå miste om värdefulla möjligheter

Framväxten av intellligent systemutveckling

Med den ökande användningen av digitala system i dagens samhälle blir framstegen inom AI-området alltmer uppenbara. Modeller för språkbehandling har utvecklats till en punkt där vem som helst med internetanslutning kan ställa frågor för att snabbt få svar. Inom mjukvaruutveckling förblir problemlösning en central uppgift för utvecklare, och snabb återkoppling visar sig vara särskilt värdefull i projektbaserade arbetsmiljöer med tidsbegränsningar. Genom en kvalitativ metod baserad på semistrukturerade intervjuer undersökte denna studie användningen av AI-verktyg inom mjukvaruutveckling, och utforskade den framtida rollen för mjukvaruutvecklare i en arbetsmiljö där AI har potential att kraftigt förändra arbetsmetoder. Denna studie föreslår att AI-verktyg kommer fortsätta ge utvecklare värdefullt stöd i form av innovativ, lösningssökande återkoppling samt ersätta repetitiva uppgifter. Studiens resultat avslöjar däremot en uttryckt oro för anpassning till AI-verktyg, och hur dessa bör anpassas för att fungera inom organisationen. Tillgången till AI medför potentiella förändringar i systemutvecklingsprocesser, och om dessa inte beaktas kan utvecklare och organisationer gå miste om värdefulla möjligheter