Reliablity procedures are developed for girder bridges. Load models are based on the available statistical data. The derivation of load models is described in other papers. Resistance models are developed by simulations using the available test results for materials and components. The girder behavior is described by a moment curvature relationship. Bridge capacity is determined in terms of the maximum truck load before failure. The analysis is performed for a single unit truck, a semitrailer, and combinations of these trucks. For a given truck position, the load is gradually increased until the deformation (maximum deflection) exceeds the critical level. The developed resistance models are used in the reliability analysis. Reliability indices are calculated for noncomposite and composite steel girders, reinforced concrete T‐beams, and prestressed concrete girders. The calculations are performed for girders and structural systems. Reliability indices for the system are higher than for girders. The effect ...

A significant challenge facing motor carriers and engineers in this nation is the limitation of vehicle size and weight based on pavement and bridge capacity. However, the current demands of society and industry occasionally require a truck to carry a load that exceeds the size and weight of the legal limit. In these cases, engineering analysis is required before a permit is issued to ensure the safety of the structures and roadways on the vehicle's route. A truck with a wheel gauge larger than the standard 1.83 m (6 ft) gauge requires additional engineering effort because the wheel load girder distribution factors (GDFs) established by AASHTO cannot be used to accurately estimate the live load in the girders. In this study, the finite-element method is used to develop modification factors for the AASHTO flexure and shear GDFs to account for oversized trucks. The results of the analysis showed that the use of the proposed modification factors with the specification-based GDFs can help increase the allowab...

In this research, the possibility of making eco-friendly concrete from available materials in the local United Arab Emirates (UAE) market was investigated. Supplementary cementitious materials, such as ground granulated blast-furnace slag (GGBS) and silica fume (SF), were utilized for decreasing the cement quantity, enhancing the particle size distribution and improving packing. In sum, 130 concrete specimens—cubes, cylinders, and prisms—from 10 different concrete mixes were tested to determine the enhancement levels in the fresh and hard properties of new concrete. The results showed the improved particle packing of the concrete, especially within the region of sizes 100–10,000 microns, produced by the Elkem Materials Mix Analyser (EMMA), closely matching the Andreassen theoretical model. The green concrete incorporating SF and GGBS possessed air content in the range 1.0–1.4% and compressive strength that is on average 11% higher than the well-packed concrete that did not contain SF or GGBS. Compared to the ACI 318 code’s predictions, the experimental findings of the optimally packed concrete’s moduli of rupture and elasticity were under-estimated by 55–69% and 0.8–8.8%, respectively. The rapid chloride permeability test (RCPT) showed results as low as 392 coulombs for mixes with supplementary cementitious materials, indicating very low chloride permeability. Microstructural analysis using a scanning electron microscope (SEM) demonstrated that concrete with supplementary materials has fewer voids, more homogeneous integration of ingredients, and an abundance of C-S-H products that supported the RCPT findings and tests of mechanical properties. The study demonstrated a significant decrease in carbon dioxide (CO₂) emissions of concrete utilizing GGBS and SF and the financial feasibility of eco-friendly concrete in the UAE.

This study considers 12 pervious concrete mixes incorporating 100% recycled coarse aggregate from old concrete demolition waste and containing various amounts of natural fine aggregate and date palm leaves fibers. First, the properties of the recycled aggregate in terms of their particle size distribution, abrasion resistance, crushing values, specific gravity and water absorption are obtained. Next, the pervious concrete density, compressive strength, tensile strength, permeability and porosity are determined by experimental testing following the relevant standards. The results are analyzed and compared to determine the influence of using recycled coarse aggregate in the mixtures and the impact of the amount of natural sand and volume fraction of the fibers on the mechanical properties, permeability and porosity of the concrete. Findings of the study showed that the use of recycled coarse aggregate in pervious concrete without fine aggregate reduced the compressive strength by 36% and tensile strength by 57%. Replacing 11.7% of the recycled coarse aggregate with natural sand and adding date palm leaves fibers in an amount equivalent to 0.64% volumetric content to such concrete helped increase the compressive strength by 16.2% and tensile strength by 3.2% above the corresponding strengths of the control mix. There is a clear relationship between permeability and porosity due to their correlation with the density of pervious concrete, and the effect of porosity on tensile strength is more influential than it is on the compressive strength. An equation that can predict the tensile strength of pervious concrete from the compressive strength is proposed, as a function of the natural fine aggregate fraction of the coarse aggregate and volumetric content of natural fibers. Results of the research confirm the feasibility of using recycled aggregate in pervious concrete mixes and the positive impact of natural fibers on the mechanical properties.