Test Data Bank Research Articles

Post-fire flexural buckling and resistances of square recycled aggregate concrete-filled stainless steel tube (RACFSST) columns

The flexural buckling behaviour and residual resistances of square recycled aggregate concrete-filled stainless steel tube (RACFSST) columns after exposure to fire are studied in this paper, based on experiments and numerical modelling. Twelve column specimens, fabricated from concretes with three recycled coarse aggregate replacement ratios (0%, 35% and 70%), were tested after exposure to the ISO 834 standard fire for 0 min (i.e. at ambient temperature), 15 min, 30 min and 45 min. The experimental investigation included heating of specimens, cylinder tests as well as post-fire initial global geometric imperfection measurements, tensile coupon tests and pin-ended column tests. The test setups, procedures and results were fully reported and the ductility indices, lateral deflection distributions and longitudinal strains were discussed and analysed. A numerical investigation was afterwards carried out, where the test results were used to validate thermal and mechanical finite element models; upon validation, parametric studies were conducted to expand the test data bank over a wider range of cross-section dimensions and member lengths. On the basis of the test and numerical data, the relevant design rules for square natural aggregate concrete-filled carbon steel tube columns at ambient temperature, as set out in the European code, Australian/New Zealand standard and American specification, were assessed, using post-fire material properties, for their applicability to square RACFSST columns after exposure to fire. It was found from the assessment results that the three design codes resulted in overall accurate and consistent post-fire flexural buckling resistance predictions but some were unsafe.

Local buckling behaviour of Q690 high strength steel press-braked elliptical hollow section stub columns: Testing, numerical modelling, and design

This paper presents comprehensive investigations on the local bucking behaviour of Q690 high strength steel (HSS) press-braked elliptical hollow section (EHS) stub columns subject to concentric compression experimentally. In comparison with conventional hot-finished EHS or cold-rolled EHS, the press-braked EHS provides high precision, great construction productivity and the fabricated geometries are not limited to production assembly instrumentation. HSS press-braked EHS fabricated through press-braking process was expected to exhibit distinct behaviour compared with their counterparts constructed from the conventional fabrication routes. Well-understanding of their performance at the levels of material, and cross-section level is essential. Material properties were obtained through tensile coupon tests. Residual stresses in both membrane and bending types were measured and recorded and their impact on structural performance was also assessed. Initial local geometric imperfection measurements were conducted for all the specimens. In conjunction with experimental studies, the finite element (FE) models of Q690 HSS press-braked EHS stub columns were developed. The accuracy of the FE model for HSS press-braked EHS stub column was asserted by comparing the numerical predictions with the tested results. An extensive parametric study was conducted to generate structural performance data with a wider range of cross-section slenderness to complement the test data bank. The cross-section classification for conventional CHS codified in existing standards and the proposed slenderness limits by various researchers were evaluated. The existing slenderness limits cannot be extended to HSS press-braked EHS investigated in this study, a new slenderness limit is proposed. Moreover, the advanced design approaches of Direct Strength Method (DSM) and Continuous Strength Method (CSM) were assessed for their applicability to the cross-section resistance predictions of the examined EHS stub columns.

Testing, modelling and design of concentrically-loaded concrete-encased concrete-filled steel tube slender column

Concrete-encased concrete-filled steel tube (CECFST), an innovative type of concrete-steel composite structure, has been increasingly employed in mega construction projects due to its outstanding structural performance. However, although intermediate and sometimes slender columns have become commonplace in high-rise buildings and large-scale bridges, the research on member behaviour of CECFST slender columns barely exists in the current literature. In this paper, a comprehensive experimental and numerical modelling programme was conducted to study buckling resistance and structural behaviour of CECFST slender columns. Pin-ended concentric load column tests were carried out on four slender columns, together with a fixed-ended stub column as a reference specimen. Key test results of all specimens, such as failure modes and effects of slenderness on strength, ductility and stiffness, showed that buckling failure and P-δ effect degraded the performance indices of CECFST slender columns. Afterwards, a finite element (FE) modelling programme was performed, where a range of member imperfections was incorporated and validated against test results. Parametric studies were then conducted to supplement the test data bank, from which over sixty FE results were generated. The test and FE failure loads obtained were utilised to examine the applicability of current design methods in the European code, American specification and Australian standard. The buckling curve 'b' set out in the European code was found to result in the most accurate and consistent buckling resistance predictions, while the American specification and Australian standard generally yielded over-conservative and unsafe results, respectively.

Change in weight status and academic performance among senior high school students in Taiwan.

This study examines how the changes in weight status across the spectrum of a senior high school study are associated with academic performance measured by the university entrance exam scores. A unique dataset which compiles a national health examination profile and the General Scholastic Ability Test data bank in Taiwan was constructed. The final sample comprised 149,240 senior high school students of which 70,662 were males and 78,578 were female students. The school-level fixed effect models were estimated. Students who were either (a) not overweight in the first year but overweight in the third year of senior high school, (b) overweight in both the first and third year, or (c) overweight in the first year but not overweight in the third year, were more likely to score lower on the university entrance exam, compared with their never-overweight counterparts. The findings differ by gender and test subjects. The change in weight status during senior high school period is associated with subsequent university entrance exam outcome. Students who start senior high school being overweight should be paid attention. School-based programs and practices need to be implemented to reduce the prevalence of overweight among students.

Conception of an environmental technology data bank

For documentation, analysis and application of the state of the art and its development in environmental technologies, an information system should be conceived by using modern information and communication techniques. Within this project the pilot phase is being carried out, in which in co–operation with the established working party (industry, host and authorities) a test data bank is being implemented including emission control technologies of combustion systems, which emphasises the experience of applied emission control systems. For the model description of the emission control technologies into the data bank a special method was developed. Moreover a user structure system is shown, which allows for efficient access to the information without using a separate search language.

Deformations at flexural yielding of members with continuous or lap-spliced bars

Models are developed and calibrated for the moment, the chord rotation and the secant stiffness at flexural yielding of reinforced concrete beams, rectangular columns or walls and members of T-, H-, U- or hollow rectangular section, on the basis of a databank of tests on members with continuous bars. Criteria are developed for the identification of adverse shear effects on the yield moment. The models apply only to members whose yield moment is not reduced by shear effects. They employ simple, explicit expressions suitable for practical application without moment–curvature analysis. They are extended to members with bars lap-spliced starting at the end section. The effect of biaxial loading on member yielding is examined. Most of the models have been adopted in Eurocode 8, Part 3.

The quest for logia psyche in business leadership: An empirical study of cognitive moral development in construction industry dyads

AbstractThis research study examines the ageless human debate of the body versus the soul, testing leadership in the industry of building constructors. Based on Kohlbergian theory of cognitive moral development, the multidisciplinary literature review advances the proposition that moral development proceeds in waves of egoism, leading to altruism that is couched in power—“the apple of the eye.” The results from respondents of the Iowa Architects Institute of America (n = 93) indicated that, despite their higher education and aesthetic interests, the sample of architects ranked low on moral maturity level compared to the average of the Defining Issues Test data bank as a whole. Principled scores were 36.4 for architects and 39.1 for the data bank. This research also compared the moral maturity of intra‐industry groups in marketing dyads consisting of architects, contractors, and suppliers using analysis of variance. Again, it was expected that architects with higher education and aesthetic interests would rank highest. Findings of post hoc comparisons revealed no significant difference in moral maturity level between architects and contractors engrossed in the same power paradigm (p = 1.00), yet a significant difference existed between architects and suppliers (p = 0.024). This implication is consistent with the teleological ethical pattern that is prevalent in research studies of salespeople.

Computerized screening of children congenital heart diseases

In this paper, we propose a method for automated screening of congenital heart diseases in children through heart sound analysis techniques. Our method relies on categorizing the pathological murmurs based on the heart sections initiating them. We show that these pathelogical murmur categories can be identified by examining the heart sound energy over specific frequency bands, which we call, Arash-Bands. To specify the Arash-Band for a category, we evaluate the energy of the heart sound over all possible frequency bands. The Arash-Band is the frequency band that provides the lowest error in clustering the instances of that category against the normal ones. The energy content of the Arash-Bands for different categories constitue a feature vector that is suitable for classification using a neural network. In order to train, and to evaluate the performance of the proposed method, we use a training data-bank, as well as a test data-bank, collectively consisting of ninety samples (normal and abnormal). Our results show that in more than 94% of cases, our method correctly identifies children with congenital heart diseases. This percentage improves to 100%, when we use the Jack–Knife validation method over all the 90 samples.

Investigations on the punching behaviour of reinforced concrete footings

The punching shear capacity of footings varies significantly for different codes. One reason is that the amount of the soil reaction to be deducted from the punching load differs from one code to another. The aim of the present investigation is to develop a design model for the punching strength of footings taking into account the soil-structure-interaction. The results of five punching tests on reinforced concrete footings supported on soil are presented. The experimental results indicate that the angle of the shear failure plane is steeper than observed in punching tests on flat slabs and the shear slenderness seems to affect the punching shear capacity significantly. Based upon the findings and a test data bank an advanced design model is derived, which is based on the BS 8110-1:1997 provisions.

Experimental Investigations on Punching Behavior of Reinforced Concrete Footings

This article reports on a study of 5 reinforced concrete footings that were tested to investigate the punching shear failure of footings. Contrary to most of the research in this area, in which footings are supported on springs or on a column slab, this study used concrete column footings realistically supported on sand. The tested specimens had different slab thicknesses and reinforcement ratios. The consistency of the sand was also varied as a test parameter (dense and loose). Four footings had no shear reinforcement, whereas the fifth one included shear reinforcement (vertical bars mechanically anchored at top and bottom by welded anchor plates). Results showed that the angle of the failure shear crack is steeper than that observed by punching tests of flat slabs. In addition, the shear slenderness seems to significantly affect the punching shear capacity. The consistency of the sand has no other influence on the soil pressure distribution underneath the footing. The authors report on their study and review other tests from the literature, developing a test data bank. They also compare ACI and Eurocode 2 provisions and rules for the design of footings with their present test results as well as the information from the test data bank.

Structure solution with PATSEE

Abstract Patterson search is a powerful tool for solving difficult crystal structures since it actively uses chemical information. Our program PATSEE, which attempts to combine the merits of Patterson and direct methods in order to locate a fragment with known geometry in the unit cell, has solved a large number of crystal structures during the last decade and proved to be reliable and widely applicable. We have tested PATSEE successfully on 20 structures of different size and complexity contained in a test data bank using fragments either taken from related crystal structures or calculated by force-field methods. Even structures with several torsional degrees of freedom (like those of oligopeptides) could be solved convincingly. As a result, general experiences – such as requirements for the minimum size and the accuracy of a search fragment, the reliability of the various figures of merit, the chances to locate single atoms and to tackle larger structures – were gained, which should help in finding an optimum strategy for the solution of problem structures with PATSEE.

Performance of a two-phase gas/liquid flow model in vertical wells

This paper presents application of a recently developed method for predicting two-phase gas/oil pressure-drop in vertical oil wells. The new method, which is flow-pattern based, is capable of handling flow in both circular and annular channels. Five principal flow regimes-bubbly, dispersed bubbly, slug, churn and annular - are recognized while developing appropriate correlations for predicting void fraction and pressure-drop in each flow regime. Standard oilfield correlations are used for estimating PVT properties of oil and gas: Standing's correlation for solution gas-oil ratio; Katz's correlation for oil formation volume factor; Standing's, and Chew and Connally's correlations for dead and live oil viscosities, respectively; and Lee et al.'s correlation for gas viscosity. A finite-difference algorithm is developed to compute pressure gradient in a wellbore. Computations performed on 115 field tests, involving all the two-phase flow regimes, suggest that the new method performs better than the Aziz et al. correlation. Further comparison of the new method's performance with other standard methods, such as, Orkiszewski, Duns and Ros, Beggs and Brill, Hagedorn and Brown, and Chierici et al., reveals its consistency and improved performance. The test data bank used in this study is that previously used by other authors; thus, validation of the new method is demonstrated with an independent data set.