Study on the Differential Shrinkage of Composite Prestressed Concrete Beam

This paper describes the results of experimental studies made on the effects of differential shrinkage of the composite beams having the flange or the upper half portion cast on the precast prestressed beam. The cast-in-place concrete was made with artificial lightweight aggregates. In all thirty beam specimens were fabricated and the variables involved in the specimens were : shape of cross-section, amount of shear connecter, ratio of shear span to beam depth, and age at casting slab. Differences of shrinkage and creep characteristics between the cast-in-place lightweight concrete and the precast normal concrete were measured by using the control specimens. The differential shrinkage set up internal stresses in the composite construction and its effects on the cracking moment and on the ultimate strength of the composite beams were investigated and compared with the theoretical analysis. It is concluded that the differential shrinkage has so profound an effect that it should be taken into consideration in design, especially when the slab concrete is placed at a later time

Strain Measurements of Prestressed Concrete Cylindrical Tank Walls

This paper presents the results of strain measurement on prestressed cylindrical concrete tank walls at the time of transferring of prestress. Freyssinet's method as well as Preload's method are employed to transfer prestress to the prestressed concrete tank walls. By means of Carlson type strainmeters embeded in the concrete, strains due to prestressing and bending moments accompanied by prestressing in the longitudinal direction are measured and compared with the theoretical values for each of the above described methods. The results obtained show that the prestresses applied meet fairly well the design requirements and the measured strains satisfactorily coincide with the theoretical values in the angular (tangential) direction. It is expected that comparatively large strains occur due to the circumferential prestressing, while the measured strains are approximately a half of the theoretical values

Construction of Prestressed Concrete Pavement Slabs in Osaka City

This paper describes the prestressed concrete pavement slabs, 60 m and 40 m in length which were constructed in Osaka City in January of 1958. Prestressing steel was laid in both longitudinally and transversely in the 60 m slab, and diagonally with angles of intersection of about 60 deg. in the 40 m slab. The construction and testing of the pavement slabs are described in detail. The results prove the superior behavior of prestressed slabs, especially in their elastic recovery, and indicate that. such construction could be advantageously utilized in future pavement construction when it becomes economically comparable with other forms of construction

Expansion of signaling genes for adaptive immune system evolution in early vertebrates

<p>Abstract</p> <p>Background</p> <p>The adaptive immune system (AIS) of jawed vertebrates is a sophisticated system mediated by numerous genes in specialized cells. Phylogenetic analysis indicates that emergence of the AIS followed the occurrence of two rounds of whole-genome duplication (2R-WGD) in early vertebrates, but little direct evidence linking these two events is available.</p> <p>Results</p> <p>We examined the relationship between 2R-WGD and the gain of AIS-related functions by numerous genes. To analyze the evolution of the many genes related to signal transduction in the AIS (defined as AIS genes), we identified groups of genes (defined as AIS subfamilies) that included at least one human AIS gene, its paralogs (if any), and its <it>Drosophila </it>ortholog(s). Genomic mapping revealed that numerous pairs of AIS genes and their paralogs were part of paralogons – series of paralogous regions that derive from a common ancestor – throughout the human genome, indicating that the genes were retained as duplicates after 2R-WGD. Outgroup comparison analysis revealed that subfamilies in which human and fly genes shared a nervous system-related function were significantly enriched among AIS subfamilies, as compared with the overall incidence of shared nervous system-related functions among all subfamilies in bilaterians. This finding statistically supports the hypothesis that AIS-related signaling genes were ancestrally involved in the nervous system of urbilaterians.</p> <p>Conclusion</p> <p>The current results suggest that 2R-WGD played a major role in the duplication of many signaling genes, ancestrally used in nervous system development and function, that were later co-opted for new functions during evolution of the AIS.</p

Plastic Flow of Reinforced Concrete

We present herein the theoretical analysis of plastic flow of reinforced concrete and the test results obtained during about fourty-six weeks of sustained loading on twenty-three reinforced concrete columns. Two conditions of reinforcement were investigated for the columns of same size. This research program was intended to examine the effects of the time of loading on the plastic flow of reinforced concrete. By the results obtained, we found that the Whitney's Law pertaining to the plastic flow of concrete can also be applied to the reinforced concrete when the ratio of reinforcement is comparatively low, but in. case of high percentage in the ratio of reinfocement, due consideration must be given

Studies on the Yield of Plastic Hinges in Concrete Beams

Experimental studies were carried out to investigate the yield of plastic hinges in reinforced and prestressed concrete beams. Eighty-eight simple beams and thirty-two two-span continuous beams were tested under static loading to failure and theoretical analysis was made as to the rotation capacity of plastic hinges and the redistribution of internal bending moments. The rotation capacities of plastic hinges were analysed using the reinforcement index q. To examine the yield of plastic hinges in continuous beams, the measured strengths of beams were compared with those calculated values based on the simple beam tests. Though a prestressed concrete beam does not show any definite yield phenomena, the plastic rotation can also be calculated just as in case of reinforced concrete beams. But the rotation capacities of the former are a good deal smaller than that of the latter. The yield of plastic hinges though partly incomplete, were recognized both in prestressed and reinforced concrete beams

Creep of Eccentrically Loaded Short Reinforced Concrete Columns

Presents methods and results of an experimental and analytical investigation undertaken to clarify the creep behavior of reinforced concrete members subject to sustained combined bending and axial load. A total of 32 column specimens were tested during 46 weeks of sustained loading, of which 8 were plain concrete specimens, and 24 were tied columns with 2.09 and 3.72 per cent reinforcement. Creep characteristics of concrete was determined by the plain concrete specimens. Three conditions of eceentricity, which varied from Oto 0.5 times the depth of the column cross section, were investigated in each of two different amounts of reinforcement. A general analysis was developed, by means of which the creep of the reinforced concrete member subject to sustained eccentric load with large eccentricity may be explained, and the redistribution of stresses in concrete and reinforcement, the variation in deformation of column may be predicted with satisfactory accuracy