Experimental Test Program Research Articles

The Possibility of Making a Composite Material from Waste Plastic

The plastic is the most used man-made material in the world through their specific characteristics such as easy manufacturing and shaping, cheaper cost and low density. It is very useful in in different areas such as medicine, architecture, construction and transport. Unfortunately after the use are thrown in nature. Their accumulation poses an environmental problem. Due to the non-biodegradable. The utilization of waste plastic in manufactory of another materiel is a partial solution environmental that will reduce the proportion of waste plastic incineration or landfill.This work focuses on the Possibility of Making a Composite Material from à sand dune (A natural source abounds) and recycled height density polythene (HDPEr) by mixing the amount. The composite has been designated as roof tile. An experimental test program was conducted on the polymer roof tile containing different percentages (30%, 40%, 50%, 60%, 70% and 80%) of recycled (HDPEr) from the weight of the mixture. Experimental tests were conducted on density, the breaking load by flexural and impermeability test. In this present study, the density of polymer roof tile varies from 1.379 to 1.873 g/ cm3.. The breaking strength by flexural of all polymer roof tile mix were below the resistance of Clay roof tile. A good impermeability gives compared to the control roof tile.

Mixing Methods Evaluation of a Styrene-Acrylic Based Liquid Polymer for Sand and Clay Stabilization

In recent years, alternative soil stabilizers to supplement to cementitious soil stabilizers have been attempted for some applications and provided promising results. This study focuses on the application of a low viscosity liquid polymer for shallow soil improvement. The mixing method of soil specimens treated with the liquid polymer soil stabilizer, which belongs to Styrene Acrylic family, was studied through an experimental testing program. The tested soils included poorly graded sand and sulfate-rich clay. The water, liquid polymer and dry soil were mixed with different sequence to assess the effect on strength. The specimens were cured in controlled environment for up to 35 days before tested. It was found that the curing of the polymer stabilizer in sand and clay were time consuming and took to a month to reach their full strength. The mixing method did not show tangible difference for stabilized sandy specimens and demonstrated significant effect on stabilized clay specimen. Specifically, as to clay, when water was added after the dried soil and polymer were thoroughly, no improvement was observed.

Experimental Cyclic Behavior of Precast Hybrid Beam-Column Connections with Welded Components

Post-earthquake observations revealed that seismic performance of beam-column connections in precast concrete structures affect the overall response extensively. Seismic design of precast reinforced concrete structures requires improved beam-column connections to transfer reversed load effects between structural elements. In Turkey, hybrid beam-column connections with welded components have been applied extensively in precast concrete industry for decades. Beam bottom longitudinal rebars are welded to beam end plates while top longitudinal rebars are placed to designated gaps in joint panels before casting of topping concrete in this type of connections. The paper presents the major findings of an experimental test programme including one monolithic and five precast hybrid half scale specimens representing interior beam-column connections of a moment frame of high ductility level. The required welding area between beam bottom longitudinal rebars and beam-end plates were calculated based on welding coefficients considered as a test parameter. It is observed that the maximum strain developed in the beam bottom flexural reinforcement plays an important role in the overall behavior of the connections. Two additional specimens which include unbonded lengths on the longitudinal rebars to reduce that strain demands were also tested. Strength, stiffness and energy dissipation characteristics of test specimens were investigated with respect to test variables. Seismic performances of test specimens were evaluated by obtaining damage indices.

Consolidation behavior of an unsaturated silty soil during drying and wetting

In this work, the effect of hysteresis phenomenon on the consolidation behavior of an unsaturated silty soil was investigated through a program of experimental tests. Compacted samples were prepared by the slurry method and experimental tests were carried out in a double-walled triaxial cell. Consolidation tests were conducted by the ramping method at suctions of 0, 100, 200, 250 and 300kPa on drying and wetting paths of the soil water characteristic curve. The results show that the paths of specific water volume and specific volume are not consistent during stabilization in either condition (drying or wetting). In addition, the yield stress for the wetting path is higher than that for drying. The trend of variations of the specific water volume during loading is similar to the consolidation curves for different suction. For both conditions of drying and wetting, the slope and intercept of the virgin line due to variations of specific volume and specific water volume are a function of suction. While their values decrease with increasing suction, these values are higher for the dry path than wetting.

Superhydrophobic coatings on Portland cement concrete surfaces

The objective of this study was to synthesize, characterize and evaluate the nanomaterials-based superhydrophobic (super water-repellent) coatings on Portland cement concrete (PCC) surfaces. These coatings are synthesized with nanomaterials such as polytetrafluoroethylene (PTFE), polyether ether ketone (PEEK) and silanized diatomaceous earth (DE). Using layer-by-layer (LBL) deposition technique, each coating type was deposited at four different spray durations. The water-repellency of the coated surfaces were characterized by measuring static water contact angles (WCAs). These measurements were evaluated through a statistical design-based experimental test program which revealed that the spray duration and coating type are significant variables. A skid-resistant coating composed of PTFE and PEEK was utilized to evaluate the impact of superhydrophobic coatings on pavement skid resistance.

Experimental evaluation of geosynthetics as reinforcement for shotcrete

One of the commonly used stabilization systems for rock tunnels is shotcrete. This fine aggregate mortar is usually reinforced for improving its tensile and shear strength. In deep tunnels, its capacity to absorb energy has been recently considered for design purposes, as large displacements of the wall are expected. Two of the most used materials of reinforcement are steel welded-wire mesh and fibers (steel or polypropylene) in the shotcrete mix. This study presents the results and discussion of an experimental test program conducted to obtain the load-deformation curves of reinforced shotcrete, according to ASTM C 1550, using geosynthetics grids and geotextiles as alternative reinforcement materials. In addition, plain shotcrete and steel welded-wire mesh reinforced shotcrete specimens are also considered in the experimental program as benchmark cases. The experimental results are analyzed in terms of maximum strength and toughness. Results show that the use of geosynthetics as a reinforcement material is a promising alternative to obtain shotcrete with energy absorption capacity comparable with the most common reinforcement materials used.

Mechanical strength of ground WC-Co cemented carbides after coating deposition

Manufacturing of hardmetal tools often involves surface grinding, ion etching and final coating. Each stage throughout the manufacturing chain introduces surface integrity changes which may be critical for defining the final mechanical behavior of the coated tools. Within this context, an experimental test program has been developed to assess the influence of a coating (TiN) deposition on surface integrity and transverse rupture strength of a previously ground fine-grained WC-Co grade substrate. Four different substrate surface finish conditions (prior to ion etching and coating) were evaluated: as sintered (AS), ground (G), polished (P), and ground plus high temperature annealing (GTT). Surface integrity and fracture resistance characterization, complemented with a detailed fractographic analysis, were performed on both uncoated and coated samples. Results show that the surface integrity after grinding has been partly modified during the ion etching and film deposition processes, particularly in terms of a reduced compressive residual stress state at the substrate surface level. Consequently, the grinding induced strength enhancement in hardmetals is reduced for coated specimens. Main reason behind it is the change of nature, location and stress state acting on critical flaw: from processing defects existing at the subsurface (uncoated G specimens) to grinding-induced microcracks located close to the interface between coating and substrate, but within the subsurface of the latter (coated G specimens). This is not the case for AS and P conditions, where flexural strength does not change as a result of ion etching and coating. Finally, fracture resistance increases slightly for GTT specimens after coating process, possibly caused by a beneficial effect of the deposited film on the residual stress state at the surface.

Evaluation of Load Transfer in Geogrids for Base Stabilization Using Transparent Soil

The design of roadways with geosynthetic-stabilized base layers requires proper evaluation of the load-transfer mechanisms between soil particles and geosynthetics. In the case of geogrid reinforcements, the resistances mobilized on rib elements are key factors that determine the mechanical responses for both: (1) the ultimate pullout strength; and (2) the in-plane stiffness. Geogrids with different aperture shapes have rib elements along different orientations, and different rib orientations could generate different load transfer mechanisms. In this study, a new experimental testing program using transparent soil was conducted to visualize the load transfer of geogrids with different aperture shapes (e.g. rectangular, triangular). Specifically, small-scale soil-geosynthetic interaction tests were conducted using high-definition cameras. Consequently, image-processing techniques were used to obtain the displacements and deformations of geogrid specimens from digital images. The soil-geogrid interaction behaviors for geogrid specimens with different aperture shapes were evaluated and compared. Overall, multiple mechanisms for load transfer between soil and geogrids with different geometric characteristics could be characterized and quantified using new techniques involving transparent soil and digital image analysis.

Mechanical behavior investigation of steel connections using a modified component method

The component method is an analytical approach for investigating the moment.rotation relationship of steel connections. In this study, the component method was improved from two aspects: (i) load analysis of mechanical model; and (ii) combination of spring elements. An optimized component method with more reasonable component models, spring arrangement position, and boundary conditions was developed using finite element analysis. An experimental testing program in two major-axis and two minor-axis connections under symmetrically loading was carried out to verify this method. The initial rotational stiffness obtained from the optimized component method was consistent with the experimental results. It can be concluded that (i) The coupling stiffness between column and beam flanges significantly affects the effective height of the tensile-column web. (ii) The mechanical properties of the bending components were obtained using an equivalent t-stub model considering the bending capacity of bolts. (iii) Using the optimized mechanical components, the initial rotational stiffness was accurately calculated using the spring system. (iv) The characteristics of moment.rotation relationship for beam to column connections were effectively expressed by the SPRING element analysis model using ABAQUS. The calculations are simpler, and the results are accurate.

Influence of Chloride Deposition on Corrosion Products

The article deals with the influence of atmospheric corrosion and corrosive environment factors on the development of a protective layer of corrosion products of the weathering steel. The main aggressive factors of atmosphere that can negatively affect corrosion rate and the development of corrosion products on the steel surface include sulfates and chlorides. The development of the protective layer of corrosion products on bridge structures designed from weathering steel is monitored by program of experimental atmospheric corrosion tests. Exposed specimens on selected bridges allow to determine the relationship between the thickness of the layer of corrosion products and corrosion losses depending on the time of exposure and local environmental conditions. For the evaluation of protective properties of corrosion layer of the weathering steel indexes PAI is applied. This article presents the part of results of field experimental atmospheric corrosion tests for selected bridge structures in Ostrava. The influence of the amount of chlorides forming insoluble compounds in corrosion products on the protective properties of corrosion layers weathering steel is monitored for these bridges.

REPAIR AND STRENGTHENING OF RC SLABS USING FERROCEMENT LAYERS REINFORCED WITH DIFFERENT FRP MESHES

Ferrocement is one of the recent methods for repair and strengthening of reinforced concrete members. It can be described as a type of thin composite material made of cement mortar reinforced with wire meshes. The wire meshes are uniformly distributed in continuous layers with relatively small diameters. In this research, an experimental test program consists of eleven RC slab specimens repaired and strengthened by ferrocement layers reinforced by traditional steel reinforcement and steel wire meshes as well as manufactured glass and carbon fiber reinforced polymer meshes. The tested slabs classified in three groups. The first group consists of three specimens as reference slabs. The second group for repaired slabs consists of four specimens. They were loaded first by 80% of the ultimate loads and then cracks were repaired and then additional ferrocement layers with different wire meshes were added. The third group for strengthened slabs consists of four specimens. They were strengthened with additional ferrocement layers with different wire meshes without preloading. Slab specimens were tested under two-point loading and subjected to incremental loads till failure. Performance of the tested slabs such as deflections, cracking and ultimate loads as well as crack patterns were investigated, analyzed and discussed in this research. The test results confirm that repair and strengthening technique using ferrocement layers gives good results. Intertwined manufactured carbon fiber wire mesh gave best results for increasing the flexural capacity of RC slabs.

Web Shear Strengthening Technique of Deep Precast Prestressed Hollow Core Slabs under Truck Loads

Precast prestressed Hollow Core Slabs (HCS), are one of the famous and widely used slabs for concrete structures all over the world and widely implemented in the Middle East. HCS are used in industrial, commercial, residential buildings, as well as, in the parking structures. This paper succeeded to present new special details for deep HCS to enhance and strengthen the web shear strength capacity of HCS 400 and 500 mm depths respectively at the open parking area. This is subjected to heavy truck wheel loads so as to achieve the LRFD Code’s requirements. However, it is noticed many web shear cracks of HCS are used at parking area at many projects in Gulf Region. On the other hand, ACI318-14 permits no shear reinforcement in prestressed HCS thickness of less than 12.5 in (320 mm). The paper presents experimental tests program, to verify the numerical finite element of deep HCS under maximum design uniform loads, in addition to the new strengthening techniques. New strengthening techniques succeed to enhance the web shear capacity by significant percentage, due to the new details for HCS 400 by 68% up to 256% increasing of the web shear capacity compared to the ordinary HCS section. Also, HCS 500 shear capacity is enhanced with different percentages of strengthening techniques by 55%, up to 197% based on the different cases of strengthening. Furthermore enhancing deep HCS shear performance; the new techniques have an advantage of an easy execution at the site; casting with structural topping, otherwise the preparation can be done in precast factory before site handover, which saves time and cost compared to the others traditional strengthening techniques.

Experimental and numerical study on the fire response of cold-formed steel beams with elastically restrained thermal elongation

Purpose This paper is mainly aimed at the structural performance of compound cold-formed galvanised steel beams under fire conditions based on the results of a large programme of experimental tests and numerical simulations. The main objective of this research was to assess the critical temperature and time of the studied beams. Other important goals of this research work were to investigate the influence of the cross-sections (C, lipped-I, R and 2R beams) and, above all, of the axial restraint (0, 0.45, 3, 7.5, 15, 30, ∞ kN/mm) to the thermal elongation of the beam and the rotational restraint at beam supports (0, 15, 80, 150, 300, 1,200 and ∞ kN.m/rad) on the fire resistance of this kind of beams. Design/methodology/approach This paper still provides details of the simulation methodology for achieving numerical stability and faithful representation of detailed structural behaviour and compares the simulation and experimental results, including beam failure modes, measured beam axial forces and beam mid-span deflections. Findings Good agreement between Abaqus simulations and experimental observations confirms that the finite element models developed with the Abaqus/standard solver are suitable for predicting the structural fire behaviour of restrained cold-formed steel beams. Originality/value The results showed above all that the effect of the stiffness of the surrounding structure seems to decrease with the increasing slenderness of the beams.

Experimental study on the hydrodynamic behaviour of an FPSO in a deepwater region of the Gulf of Mexico

As offshore oil and gas exploration moves progressively toward greater water depths, it becomes more challenging to predict the environmental forces and global responses of floating production storage and offloading (FPSO) systems and the dynamic behaviour of the mooring lines and risers. The validation of complex numerical models through scale model experimental testing is restricted by the physical limits of the test facilities. It is not feasible to install the equivalent full length mooring lines and riser systems and select an appropriate scale model for reducing the uncertainties in the experimental test programme for deepwater and ultra-deepwater conditions. The combination of an appropriate scale FPSO model with a suitable level of equivalent effect reduced depth using a hybrid passive truncated experimental methodology for the mooring lines and risers is a practical approach.Following recent discoveries, FPSO has been proposed for a portion of the planned development in the southern Gulf of Mexico (GOM) in water depth ranging from 1000 to 2000m. Based on a scale model and a hybrid passive truncated experimental method for mooring lines and risers, this paper investigates the global response of an FPSO, as well as the dynamics of mooring lines and risers in the context of prevailing environmental conditions for field development in a specific deepwater location in GOM. The experiments revealed that the main horizontal motion response of the FPSO (surge) under non-collinear loading condition is almost two-times that of the collinear loading condition. The mooring lines in the non-collinear condition are more sensitive to the dynamic response and risers appear to have an important influence on the low frequency damping.

EXPERIMENTAL RESULTS ON THE SHEAR BEHAVIOUR OF STEEL FIBRE SELF-COMPACTING CONCRETE (SFSCC) BEAMS

This paper presents an experimental test program that was carried out to investigate the shear performance of steel fibre self-compacting concrete (SFSCC) beams. In this paper, the mechanical performance of results from all mixtures used to cast normal concrete (NC), self-compacting concrete (SCC) and steel fibre self-compacting concrete (SFSCC) were also investigated. In total, 27 cubes, 9 cylinders, 9 prisms and 9 beams were prepared for the assessment of mechanical properties of three different mixtures. Four beams (125 mm x 250 mm x 2200 mm) were tested and cast using three different concrete mixtures, having two different spacing of stirrups as a result of 50% reduction of the stirrups amount. Three beams with different mixtures having similar stirrups spacing 125mm while the fourth beam with SFSCC mixes having 250mm stirrups spacing. The results show that the mechanical properties were positively affected with steel fibres inclusion. The addition of steel fibres showed an increment up to 40% in the shear load capacity for B-SFSCC125 compared to B-NC125 and B-SCC125. In addition, the crack pattern of B-SFSCC was found better than B-NC and B-SCC.

Numerical modelling and fragility assessment of typical freestanding building contents

The paper assesses the adequacy of existing numerical models in predicting the seismic response of freestanding nonstructural components that exhibit rocking-dominated behavior. Based on a previous experimental test program on hospital building contents carried out by the authors, the study focuses on two different modelling techniques: (a) finite element method (FEM) and (b) rigid block model. The ability to predict the response of two hospital cabinets tested in the laboratory is verified by comparing the numerical response with the experimental one. The applicability and limitations of each modelling technique are also discussed. The outcomes of the present study show that both the adopted modeling techniques can provide a reliable prediction of the occurrence of rocking mechanism in hospital cabinets. Rigid block model can also predict the occurrence of the overturning, whereas FEM model can provide a prediction of the acceleration distribution at different locations of the cabinets, e.g. at different shelf levels. The efficiency of different intensity measures in predicting the damage states in rigid block is estimated. Comprehensive incremental dynamic analyses on different rigid blocks highlight that dimensionless intensity measure PGA/(g, tgalpha ) is the most efficient intensity measure to predict rocking and overturning in small rigid blocks, whereas p, PGV/left( {g ,tgalpha } right) is the most effective for large rigid blocks. Such intensity measures also allow generalizing the results to different rigid blocks, through the definition of a fragility approach.

A novel simulation for the design of a low cycle fatigue experimental testing programme

This paper proposes an innovative concept for the design of an experimental testing programme suitable for causing Low Cycle Fatigue crack initiation in a bespoke complex notched specimen. This technique is referred to as the Reversed Plasticity Domain Method and utilises a novel combination of the Linear Matching Method and the Bree Interaction diagram. This is the first time these techniques have been combined in this way for the calculation of the design loads of industrial components. This investigation displays the capabilities of this technique for an industrial application and demonstrates its key advantages for the design of an experimental testing programme for a highly complex test specimen.

Impact of the reinforcement layout on the load capacity of reinforced concrete half-joints

A reinforced concrete half-joint beam has a complex geometry that includes both a locally disturbed nib region and a full depth section. While this configuration simplifies the design and construction procedures, half joint structures rely on the internal steel reinforcement to transfer force from the nib into the bulk of the beam. When assessing existing reinforced concrete half-joints, engineers can be confronted with internal reinforcement layouts that do not correspond to the as-designed drawings and/or do not comply with current design practice. Bars may be missing or the location, percentage and spacing of the steel reinforcing bars may be non-compliant.To provide a better understanding of the contribution of the internal steel reinforcing bars found in a typical half joint detail, an experimental test program on full-scale half-joint beams was undertaken. Four different scenarios were tested to identify the impact of specific reinforcing bars. A reference specimen was designed in accordance with existing practice. The reference beam, and beams with either missing diagonal reinforcement, missing horizontal reinforcement or a reduced amount of shear reinforcement were tested.All the beams exhibited nib failures with the exception of the beam where the shear reinforcement was reduced. In this case, the failure mode changed from a nib failure to a full-depth failure. The results indicated that if certain bars are missing the overall load bearing capacity of a half-joint could be approximately 40% lower than that of a properly designed detail, but that a redistribution of forces was noted.

Influence of web stiffeners on cold-formed steel beams subjected to fire

Purpose This paper aims to present the results of a study on the behaviour of cold-formed galvanized steel beams subjected to fire, using the results of a large programme of experimental tests. Design/methodology/approach The research investigated the influence of web stiffeners in the sections and the stiffness of the surrounding structure, including the axial and rotational restraining to the thermal elongation, on the flexural behaviour of the beams in case of fire. In other words, the structural response of different open cold-formed steel beams, with and without web stiffeners, was compared in case of fire. Findings The results showed that a good choice between using cold-formed steel beams, with and without web stiffeners, may depend on the section shape and the internal forces generated in these members during a fire. Originality/value Temperatures in the furnace and at several points of the beams, as well as deformations and restraining forces and moments, were measured to achieve those goals and consequently to assess the critical time and temperature of these beams.

Response of Municipal Solid Waste to Mechanical Compression

AbstractThe compressibility of municipal solid waste (MSW) is of engineering interest as it affects the short-term and long-term performance of landfills, as well as their expansion, closure, and postclosure development. An assessment of the field settlement behavior of MSW can be reliably executed only when the various mechanisms contributing to the settlement are properly taken into account. A comprehensive large-size experimental testing program that involved a total of 143 one-dimensional compression tests from five landfills, in Arizona, California, Michigan, and Texas of the United States as well as Greece was executed to systematically assess the compressibility characteristics of MSW subjected to a compressive load. Emphasis is given to the influence of waste structure, waste composition, unit weight, and confining stress on the compressibility parameters that are used in engineering practice, such as the constrained modulus and compression ratio, as well as long-term compression ratio due to mech...