In-plane shear behaviour of composite walling with profiled steel sheeting

This thesis introduces a novel form of double skin composite walling with profiled steel sheeting and an infill of concrete. This is a logical extension of research on composite slabs with profiled steel sheeting currently known as popular "Fastrack" construction. The composite walling is thought to be specially applicable as shear or core walls in steel frame buildings. The profiled steel sheeting will act as a temporary shear bracing to stabilise the frame against wind and destablising forces during construction and also act as a form work for infill of concrete. In the service stage, they will act as a reinforcement to carry axial, lateral and in-plane forces. This thesis investigates the behaviour of composite walls under in-plane shear so that they can be used as shear elements in buildings. The investigation includes analytical, numerical and small scale model tests. Design recommendations for the composite walls are the final aim of the research. The investigation is based on the concept that the in-plane shear strength and stiffness of the composite wall will be derived from the individual sheeting, concrete core and from the interaction between the two. Based on above, individual behaviour of the sheeting and concrete core was studied before considering the composite wall as a whole. A shear rig has been designed and fabricated to carry out the model tests of approximately 1/6 th scale using very thin sheeting (profiled in house) and microconcrete. Analytical equations for the shear strength and stiffness of the sheeting, profiled concrete and composite wall are derived. These equations are validated by model tests and finite element analysis. Finite element analysis included modelling of composite walling with full composite action and some parametric studies using interface elements. The stiffness of the composite wall is found to be greater than the individual summation of stiffness of the sheeting and concrete core. The profiled steel sheeting will provide sufficient shear bracing to the frame during construction. The composite wall is capable of taking high in-plane shear loads which is greater than the summation of individual capacity of the sheeting and concrete and confirms its potential to be used as shear elements in buildings. Simple equations for the calculation of shear strength and stiffness of the composite wall are derived which can safely be used for design purposes. Further research directions are also outlined.This thesis introduces a novel form of double skin composite walling with profiled steel sheeting and an infill of concrete. This is a logical extension of research on composite slabs with profiled steel sheeting currently known as popular "Fastrack" construction. The composite walling is thought to be specially applicable as shear or core walls in steel frame buildings. The profiled steel sheeting will act as a temporary shear bracing to stabilise the frame against wind and destablising forces during construction and also act as a form work for infill of concrete. In the service stage, they will act as a reinforcement to carry axial, lateral and in-plane forces. This thesis investigates the behaviour of composite walls under in-plane shear so that they can be used as shear elements in buildings. The investigation includes analytical, numerical and small scale model tests. Design recommendations for the composite walls are the final aim of the research. The investigation is based on the concept that the in-plane shear strength and stiffness of the composite wall will be derived from the individual sheeting, concrete core and from the interaction between the two. Based on above, individual behaviour of the sheeting and concrete core was studied before considering the composite wall as a whole. A shear rig has been designed and fabricated to carry out the model tests of approximately 1/6 th scale using very thin sheeting (profiled in house) and microconcrete. Analytical equations for the shear strength and stiffness of the sheeting, profiled concrete and composite wall are derived. These equations are validated by model tests and finite element analysis. Finite element analysis included modelling of composite walling with full composite action and some parametric studies using interface elements. The stiffness of the composite wall is found to be greater than the individual summation of stiffness of the sheeting and concrete core. The profiled steel sheeting will provide sufficient shear bracing to the frame during construction. The composite wall is capable of taking high in-plane shear loads which is greater than the summation of individual capacity of the sheeting and concrete and confirms its potential to be used as shear elements in buildings. Simple equations for the calculation of shear strength and stiffness of the composite wall are derived which can safely be used for design purposes. Further research directions are also outlined

STR-928: SHEAR RESISTANCE OF COMPOSITE BEAMS WITHOUT SHEAR REINFORCEMENT

This paper presents the shear behaviour of composite beams made of combinations of high performance concretes (HPCs) such as self-consolidating concrete (SCC) and ductile Engineered Cementitious Composite (ECC). The variables in this experimental and Code based study was shear span to depth ratio, concrete types, longitudinal reinforcement and depth ratio (of ECC and SCC layer). The performance of ECC-SCC composite beams was compared with full depth normal SCC beams based on load-deformation response, stress-strain development, shear strength, failure mode, energy absorption capacity and aggregate-dowel action. The performance of American code in predicting shear strength of SCC beams including ECC-SCC composite beams was studied based on experimental results

STR-927: SHEAR RESISTANCE OF LIGHTWEIGHT SELF-CONSOLIDATING CONCRETE BEAMS

This paper presents the shear behavior of lightweight self-consolidating concrete (LWSCC) beams without shear reinforcement compared to those made with normal weight self-consolidating concrete (SCC). The variables in this experimental and Code based study was shear span to depth ratio, concrete types and longitudinal reinforcement. The performance of LWSCC was compared with normal SCC beams based on load-deformation response, stress-strain development, and shear strength and failure modes. LWSCC beams showed lower post-cracking shear resistance and the shear strength of LWSCC/SCC beams increased with the decrease of shear span to depth ratio. LWSCC beams showed higher number of cracks and wider crack width at failure than their SCC counterparts. American, Canadian and British Codes were conservative in predicting shear strength of LWSCC beams

Deterioration and corrosion in scoria based blended cement concrete subjected to mixed sulfate environment

The use of blended cements incorporating supplementary cementing materials and cements with low C 3 A content is becoming common to prevent the deterioration of concrete structures subjected to aggressive environments. This paper presents the results of an investigation on the performance of finely ground volcanic scori

MAT-712: MICROSTRUCTURAL INVESTIGATIONS ON THE SELF-HEALING ABILITY OF ENGINEERED CEMENTITIOUS COMPOSITES INCORPORATING DIFFERENT MINERAL ADMIXTURES

The present study investigates the impacts that self-healing has on the microstructure characteristics of microcracked Engineered Cementitious Composites (ECC). These have two contrasting maturity levels and, furthermore, they involve three varying mineral admixtures that have very different chemical constituents. The impact of self-healing on the transport characteristics was examined by employing rapid chloride permeability tests (RCPT). The findings indicated that, if the appropriate mineral admixture type and conditioning were chosen, it would be possible to enhance the majority of the chloride ion penetrability levels following a 30-day period of water curing. As a result, the majority of the findings were in range of the low penetrability level over the 30 days, as set by ASTM C1202. The microstructural indications corroborated the findings from the experiments and provided weight to the notion that the causal factor of the healing was the appearance of calcium carbonate and C-S-H. These served to fill the crack owing to the hydration of the cementitious particles. In summary, the results indicate that the degree of self-healing is subject to variance in accordance with the contrasting chemical compositions that dominate within a certain infrastructure type over the course of its service life

STR-920: STRUCTURAL BEHAVIOUR OF REINFORCED HIGH PERFORMANCE CONCRETE COLUMNS SUBJECTED TO MONOTONIC AXIAL LOADING

This paper presents the results of experimental and analytical investigations on the structural performance of high performance reinforced concrete (HPC) columns subjected to monotonic axial loading. Reinforced columns made of self-consolidating concrete (SCC), engineered cementitious composite (ECC) and ultra-high performance concrete (UHPC) were tested to failure under axial loading. The test variables included concrete strength and length/slenderness of columns (classified as short and long columns). The UHPC and ECC columns demonstrated excellent ductility and higher energy absorbing capacity compared to their SCC counterparts. UHPC columns also illustrated higher ultimate load capacity compared to both ECC and SCC columns. The efficiency of UHPC and ECC columns was also judged based on strength and ductility ratio compared to their SCC counterparts. Existing models and other Code based equations were used to predict the axial load capacity as a part of analytical investigation. The predictions suggested the need for the modification of existing models/Code based equations for UHPC and ECC columns

MAT-731: MECHANICAL & DURABILITY PROPERTIES OF ENGINEERED CEMENTITIOUS COMPOSITES WITH DIFFERENT AGGREGATES

This paper presents the outcome of a study conducted to exhibit the effect of micro-silica sand and mortar sand on fresh, mechanical and durability properties of Engineered Cementitious Composites (ECCs). ECC is a ductile concrete characterized by strain hardening and multiple-cracking behavior under tension and shear. This study used locally available aggregates instead of standard micro-silica sand to produce cost-effective, sustainable and green ECC mixtures to be used for construction applications. ECCs prepared by both types of sands exhibited almost similar behaviour in terms of fresh, mechanical and durability properties which indicated the viability of producing ECC mixtures with mortar sand. In addition, the behaviour of a standard ECC can still be achieved when producing ECCs made of high volume fly ash (up to 70% cement replacement) along with local mortar sand. By employing results of this research, correlations were derived between mechanical and durability properties

Physiochemical and Phytochemical Properties of Wax Apple (Syzygium samarangense [Blume] Merrill & L. M. Perry var. Jambu Madu) as Affected by Growth Regulator Application

This study represents the first paper of the effects of growth regulators on the physiochemical and phytochemical properties of the wax apple fruit, a widely cultivated fruit tree in southeast Asia. Net photosynthesis, sucrose phosphate synthase (SPS) activity, peel color, fruit firmness, juice content, pH value, total soluble solids (TSSs), and the sugar acid ratio were all significantly increased in growth regulators (PGRs) treated fruits. The application of gibberellin (GA3), naphthalene acetic acid (NAA), and 2,4-dichlorophenoxy acetic acid (2,4-D) significantly reduced titratable acidity and increased total sugar and carbohydrate content compared to the control. The 50 mg/L GA3, 10 mg/L NAA, and 5 mg/L 2,4-D treatments produced the greatest increases in phenol and flavonoid content; vitamin C content was also higher for these treatments. PGR treatment significantly affected chlorophyll, anthocyanin, and carotene content and produced higher phenylalanine ammonia lyase (PAL) and antioxidant activity levels. There was a positive correlation between peel color and TSS and antioxidant activity and both phenol and flavonoid content and PAL activity and anthocyanin formation. A taste panel assessment was also performed, and the highest scores were given to fruits that had been treated with GA3 or auxin. The study showed that application of 50 mg/L GA3, 10 mg/L NAA, and 5 mg/L 2,4-D once a week from bud development to fruit maturation increased the physiochemical and phytochemical properties of wax apple fruits