Publications

The use of recycled concrete aggregates (RCA) to replace part or all of the natural coarse aggregates (NCA) in the production of concrete has been on the increase. Such use helps in the preservation of the natural resources and in the reduction in the use of landfills. Research is needed to understand the effects of using RCA on the properties of concrete. This paper reports the results of an experimental study of the pushoff shearing strength of normal-strength plain recycled aggregate concrete (RAC). A total of twenty seven pushoff specimens were cast and tested. The percentages of replacement (PR) of NCA with RCA were 0, 20%, 50% and 100%. The results showed a 7% reduction in the shearing strength for PR of 20% and 50% and a 28% reduction for PR of 100%.

First Name is required invalid characters Last Name is required invalid characters Email Address is required Invalid Email Address Invalid Email Address

This paper reports the preliminary results from an experimental program aiming to gain a better understanding of the flexural behavior of GFRP-reinforced beams made of recycled aggregates concrete (RAC).Three 32 MPa concrete beams were designed to fail in flexure by concrete crushing before bar rupture and were tested in a four-point testing setup.The control beam was made of natural coarse aggregates (NCA).The second beam was reinforced similar to the control beam but was made of RAC.The third beam was made of RAC and contained a larger amount of longitudinal GFRP reinforcement.The behavior of the beams is reported.The compressive strength in the three beams was relatively similar.The RAC beam sustained noticeably larger deformation relative to the control beam made of NCA, but the ultimate flexural strength was relatively similar.The load-deflection response after cracking of the two RAC beams was relatively linear, which is typical behavior in GFRP-reinforced beams made using NCA.Hence, this property was not affected by the use of recycled aggregates.The calculations of the ACI 440.11 code for strength were conservative for the three beams.The calculations of this code for deflection at estimated service load level severely under-estimated the deflections.

This paper reports the results of an experimental investigation of the shear behavior of beams made using hybrid fiber–engineered cementitious composites (HFECC). The paper specifically deals with the shear behavior of beams made using strain hardening engineered cementitious composites that incorporate relatively low volume ratios (Vf≤2%) of discontinuous, randomly distributed hybrid fibers (steel and polyethylene) and how the strain hardening characteristics of the fiber composite impact the shear behavior of the beam. A total of 21 beams reinforced with longitudinal steel bars and with various combinations of polyethylene (PE) and steel (ST) fibers were tested in a three-point loading setup at a shear span to depth ratio of 3. The total volume fraction of the fibers in the composites ranged from 0 to 2%, and the matrix was either cementitious paste or cementitious mortar. The beams were tested in controlled deformations to enable capturing the postpeak behavior. It is shown that HFECC made using cementitious paste was effective in increasing the shear strength by up to 8 times relative to the nonfibrous matrix. In addition, the ductility, multiple cracking behavior, and shear strain capacity of the beams were considerably improved. Improvements were also observed in the HFECC beams made with cementitious mortar but to a lesser extent, in which the shear strength increased up to 3 times relative to the nonfibrous matrix. The results also showed that when used in HFECC, the PE fibers were nearly as effective as steel fibers in increasing the shear strength. The addition of fibers allowed the beams to reach or exceed their calculated flexural capacity in spite of the relatively large longitudinal reinforcement ratio used. A fiber volume of 1% is shown to be an adequate minimum shear reinforcement for beams with compressive strengths ranging from 40 to 65 MPa, irrespective of the hybridization ratio and the binding matrix.

First Name is required invalid characters Last Name is required invalid characters Email Address is required Invalid Email Address Please select a country... Afghanistan Åland Islands Albania Algeria American Samoa Andorra Angola Anguilla Antarctica Antigua And Barbuda Argentina Armenia Aruba Australia Austria Azerbaijan Bahamas Bahrain Bangladesh Barbados Belarus Belgium Belize Benin Bermuda Bhutan Bolivia Bonaire, Sint Eustatius and Saba Bosnia and Herzegovina Botswana Bouvet Island Brazil British Antarctic Territory British Indian Ocean Territory British Overseas Territory Brunei Darussalam Bulgaria Burkina Faso Burundi Cabo Verde Cambodia Cameroon Canada Cayman Islands Central African Republic Chad Chile China Christmas Island Cocos (Keeling) Islands Colombia Comoros Congo Congo, Democratic Republic of the Cook Islands Costa Rica Côte d'Ivoire Croatia Cuba Curaçao Cyprus Czech Republic Denmark Djibouti Dominica Dominican Republic Ecuador Egypt El Salvador Equatorial Guinea Eritrea Estonia Ethiopia Falkland Islands Faroe Islands Fiji Finland France French Guiana French Polynesia French Southern Territories Gabon Gambia Georgia Germany Ghana Gibraltar Greece Greenland Grenada Guadeloupe Guam Guatemala Guernsey Guinea Guinea-Bissau Guyana Haiti Heard Island and McDonald Islands Holy See (Vatican City) Honduras Hong Kong Hungary Iceland India Indonesia Iran, Islamic Republic of Iraq Ireland Isle of Man Israel Italy Jamaica Japan Jersey Jordan Kazakhstan Kenya Kiribati Korea (the Republic of) Korea, Democratic People's Republic of Kosovo, Republic of Kuwait Kyrgyzstan Lao People's Democratic Republic Latvia Lebanon Lesotho Liberia Libya Liechtenstein Lithuania Luxembourg Macau Macedonia, Former Yugoslav Republic of Madagascar Malawi Malaysia Maldives Mali Malta Marshall Islands Martinique Mauritania Mauritius Mayotte Mexico Micronesia, Federated States of Moldova, Republic of Monaco Mongolia Montenegro Montserrat Morocco Mozambique Myanmar Namibia Nauru Nepal Netherlands New Caledonia New Zealand Nicaragua Niger Nigeria Niue Norfolk Island Northern Mariana Islands Norway Oman Pakistan Palau Palestine, State of Panama Papua New Guinea Paraguay Peru Philippines Pitcairn Poland Portugal Puerto Rico Qatar Réunion Romania Russian Federation Rwanda Saint Barthélemy Saint Kitts And Nevis Saint Lucia Saint Martin (French part) Saint Pierre and Miquelon Samoa San Marino Sao Tome And Principe Saudi Arabia Senegal Serbia Seychelles Sierra Leone Singapore Sint Maarten (Dutch part) Slovakia Slovenia Solomon Islands Somalia South Africa South Georgia South Sudan Spain Sri Lanka St Vincent And Grenadines St. Helena Ascensian and Tristan da Aunh Sudan Suriname Svalbard and Jan Mayen Swaziland Sweden Switzerland Syrian Arab Republic Taiwan Tajikistan Tanzania, United Republic of Thailand Timor-Leste Togo Tokelau Tonga Trinidad And Tobago Tunisia Turkey Turkmenistan Turks And Caicos Islands Tuvalu Uganda Ukraine United Arab Emirates United Kingdom United States United States Minor Outlying Islands Uruguay Uzbekistan Vanuatu Venezuela Viet Nam Virgin Islands (British) Virgin Islands (U.S.) Wallis And Futuna Islands Western Sahara Yemen Zambia Zimbabwe Country/Territory is required

The contribution of the shear strains to the overall deformations of reinforced concrete (RC) elements is typically neglected. However, when RC cracks in shear, its shear modulus is significantly reduced, and the contribution of the shear strains to the overall deformations of the elements is increased. Experimental testing has shown that shear deformations can be significant. Under service conditions, RC can be cracked in shear and hence, a simple method for the calculation of the effective cracked shear modulus is desired. Research has shown that the part of the shear response after cracking and before yielding can be well modeled using a straight line. This paper uses existing experimental data and the equations of the modified compression field theory (MCFT) to examine this part of the response in RC membrane elements and to develop two simple equations that can be used to characterize the straight line. The proposed equations are evaluated by comparing their results with existing experimental data on the shear response of thin RC membrane elements. The comparison includes the post-cracking response and the shear strains at estimated service level loading. A very good agreement is obtained between the experimental and the calculated results. The simplicity of the proposed equations is illustrated using a numerical example.

First Name is required invalid characters Last Name is required invalid characters Email Address is required Invalid Email Address Invalid Email Address

The contribution of shear strains to the vertical deflections in reinforced concrete (RC) beams is typically neglected for two main reasons.First, this contribution is relatively smaller than the contribution from flexure.Second, the calculation of the shear strains in cracked RC beams is complex and requires iterations.This paper presents a simple model for the calculation of the shear stress-strain response of beams after cracking of the concrete and before yielding of the steel.It represents this part of the response using a straight line whose slope and intercept stress are related to the ratios of the reinforcement and to the concrete compressive strength respectively.The results of the proposed model are shown to be simple and to compare well with experimental results.

This paper presents a simplified method for the design and analysis of non-prestressed, partially prestressed, and fully prestressed concrete beams subjected to pure torsion. The proposed model relates the torsional strength to the concrete compressive strength and to the amounts of transverse and longitudinal reinforcement. To check the adequacy of this simple method, the calculated strength and mode of failure are checked against the experimental results of 17 prestressed concrete 66 reinforced concrete beam tests available in the literature, and very good agreement is found. The simplicity of the method is illustrated by two examples, one for design and another for analysis.

This paper describes a study conducted to investigate the effects of increasing the thickness of the concrete side cover on the behavior of reinforced concrete beams tested in shear. Seven test results are reported. The thickness of the concrete side cover ranged from 5-75 mm (0.2-3 in.) for beams with a target concrete strength of 25 Mpa (3600 psi), and from 25-75 mm (1-3 in.) for beams with a target concrete strength of 40 MPa (5800 psi). The beams were reinforced in the longitudinal and transverse directions. The specimens with 75 mm (3 in.) side cover developed a sharp increase in diagonal crack width upon cracking and showed less favorable behavior. However, at estimated service stresses all specimens either remained uncracked or developed crack widths smaller than a suggested 0.3 mm (0.012 in.) limit. Spalling was observed in the specimens with larger covers near ultimate conditions, but was limited to corners of the section, leaving a considerable part of the cover on the vertical side intact. The ACI shear method and general method provided conservative estimates of the strength.

A simplified method for the analysis and design of membrane elements subjected to in-plane shearing and normal stresses is presented. The method proposed is capable of calculating the ultimate strength and the mode of failure of membrane elements. The strength curves in the method are also cast in a tabular format to further simplify the method. The results of the proposed method compare well with experimental results of 14 membrane elements reported in the literature and with the results of the modified compression field theory. Comparisons with the general method and the American Concrete Institute code are also presented. Use of the method is illustrated by two examples, one for design and the other for capacity calculation.

The behaviour of and design requirements for the transverse stiffeners of transversely stiffened web plates in plate and box girders has been studied using a fully non-linear finite element package. Using nodal line representation of the transverse stiffeners, the form and magnitude of the forces applied to the stiffeners during the collapse of the web plates were investigated. Analyses were also carried out with discrete stiffeners so that the variation in strength with stiffener size could be determined and the effect of the deflection of the stiffener assessed. A limited study was also carried out with a complete girder arrangement including flanges, so that the contribution of the transverse rigidity of the flanges to girder shear strength could be established. Analyses were undertaken for webs in shear, bending and direct compression. Using the results of the finite element study for validation purposes, a simple beam model was formulated with the stiffener and associated width of web plate acting as a beam spanning between the girder flanges, subjected to a lateral load resulting from the destabilising action of the buckling web plates. This simple design model can be used to optimise the stiffener size and is compatible with the basic approach adopted in the British Code BS5400, Part 3, which can therefore be modified to allow for the findings of this study. (A) For the covering abstract see IRRD 864118.