• Structural Monitoring and Maintenance
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• v.11 no.2
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• pp.101-126
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• 2024

To avoid irregularities in buildings, design codes worldwide have introduced detailed guidelines for their check and rectification. However, the criteria used to define and identify each of the plan and vertical irregularities are specific and may vary between codes of different countries, thus making their implementation difficult. This short communication paper proposes a novel approach for quantifying different types of structural irregularities using a common parameter named as unified identification factor, which is exclusively defined for the columns based on their axial loads and tributary areas. The calculation of the identification factor is demonstrated through the analysis of rectangular and circular reinforced concrete models using ETABS v18.0.2, which are further modified to generate plan irregular (torsional irregularity, cut-out in floor slab and non-parallel lateral force system) and vertical irregular (mass irregularity, vertical geometric irregularity and floating columns) models. The identification factor is calculated for all the columns of a building and the range within which the value lies is identified. The results indicate that the range will be very wide for an irregular building when compared to that with a regular configuration, thus implying a strong correlation of the identification factor with the structural irregularity. Further, the identification factor is compared for different columns within a floor and between floors for each building model. The findings suggest that the value will be abnormally high or low for a column in the vicinity of an irregularity. The proposed factor could thus be used in the preliminary structural design phase, so as to eliminate the complications that might arise due to the geometry of the structure when subjected to lateral loads. The unified approach could also be incorporated in future revisions of codes, as a replacement for the numerous criteria currently used for classifying different types of irregularities.

• Tuberculosis and Respiratory Diseases
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• v.45 no.4
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• pp.736-745
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• 1998

Background: Respiratory muscle interaction is further profoundly affected by a number of pathologic conditions. Hyperinflation may be particularly severe in chronic obstructive pulmonary disease(COPD) patients, in whom the functional residual capacity(FRC) often exceeds predicted total lung capacity(TLC). Hyperinflation reduces the diaphragmatic effectiveness as a pressure generator and reduces diaphragmatic contribution to chest wall motion. Ultrasonography has recently been shown to be a sensitive and reproducible method of assessing diaphragmatic excursion. This study was performed to evaluate how differences of diaphragmatic excursion measured by ultrasonography associate with normal subjects and COPD patients. Methods: We measured diaphragmatic excursions with ultrasonography on 28 healthy subjects(l6 medical students, 12 age-matched control) and 17 COPD patients. Ultrasonographic measurements were performed during tidal breathing and maximal respiratory efforts approximating vital capacity breathing using Aloka KEC-620 with 3.5 MHz transducer. Measurements were taken in the supine posture. The ultrasonographic probe was positioned transversely in the midclavicular line below the right subcostal margin. After detecting the right hemidiaphragm in the B-mode the ultrasound beam was then positioned so that it was approximately parallel to the movement of middle or posterior third of right diaphragm. Recordings in the M-mode at this position were made throughout the test. Measurements of diaphragmatic excursion on M-mode tracing were calculated by the average gap in 3 times-respiration cycle. Pulmonary function test(SensorMedics 2800), maximal inspiratory(PImax) and expiratory mouth pressure(PEmax, Vitalopower KH-101, Chest) were measured in the seated posture. Results: During the tidal breathing, diaphragmatic excursions were recorded $1.5{\pm}0.5cm$, $1.7{\pm}0.5cm$ and $1.5{\pm}0.6cm$ in medical students, age-matched control group and COPD patients, respectively. Diaphragm excursions during maximal respiratory efforts were significantly decreased in COPD patients ($3.7{\pm}1.3cm$) when compared with medical students, age-matched control group($6.7{\pm}1.3cm$, $5.8{\pm}1.2cm$, p< 0.05}. During maximal respiratory efforts in control subjects, diaphragm excursions were correlated with $FEV_1$, FEVl/FVC, PEF, PIF, and height. In COPD patients, diaphragm excursions during maximal respiratory efforts were correlated with PEmax(maximal expiratory pressure), age, and %FVC. In multiple regression analysis, the combination of PEmax and age was an independent marker of diaphragm excursions during maximal respiratory efforts with COPD patients. Conclusion: COPD subjects had smaller diaphragmatic excursions during maximal respiratory efforts than control subjects. During maximal respiratory efforts in COPD patients, diaphragm excursions were well correlated with PEmax. These results suggest that diaphragm excursions during maximal respiratory efforts with COPD patients may be valuable at predicting the pulmonary function.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4D
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• pp.485-492
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• 2008

This study presents a viscoelastic characterization of flexible pavement subjected to moving loads. A series of field tests have been conducted on three pavement sections (A2, A5, and A8) at the Korea Expressway Corporation (KEC) test road. The effect of vehicle speed on the responses of each test section was investigated at three speeds: 25 km/hr, 50 km/hr, and 80 km/hr. During the test, both longitudinal and lateral strains were measured at the bottom of asphalt layers and in-situ measurements were compared with the results of finite element (FE) analyses. A commercial FE package, ABAQUS was used to model each test section and a step loading approximation has been adopted to simulate the effect a moving vehicle. For viscoelastic analysis, relaxation moduli of asphalt mixtures were obtained from laboratory test. Field responses reveals the strain anisotropy (i.e., discrepancy between longitudinal and lateral strains) and the amplitude of strain normally decreases as the vehicle speed increases. In most cases, lateral strain was smaller than longitudinal strain, and strain reduction was more significant in lateral direction.

• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.1
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• pp.19-37
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• 2024

Rockbolts are the primary-supports in NATM tunnels and are widely used at tunnel construction sites. Among the rockbolts methods applied in domestic tunnel design, fully grouted rockbolts are the most representative and frequently used. Fully grouted rockbolts exhibit relative behavior between the bolt and the ground due to the grout material. However, during numerical analysis for tunnel design, fully grouted rockbolts are often modeled in a way that does not reflect their behavior characteristics. This may result in underestimating or overestimating the force of the supports. Based on a literature review, it was analyzed that fully grouted rockbolts are modeled using truss element or cable element. To analyze the effect of grout properties of cable elements on rockbolts behavior, this paper compared the behavior of rockbolts in two models: one estimating grout properties based on rockbolt pull-out test data, and another assuming complete adhesion between the rockbolts and the ground by applying large grout properties. Under identical tunnel conditions, the numerical analysis was conducted by modeling the fully grouted rockbolts differently using truss and cable elements, and the tunnel behavior was analyzed. The research results suggest that modeling fully grouted rockbolts as a function of the interface effect between the bolts and the ground, specifically considering grout, is desirable. The use of pull-out test data to simulate the behavior of actual fully grouted rockbolts was considered as a valid approach.