The current market of utility poles is growing rapidly. The dominant materials that are used for this purpose are generally wood, steel, concrete, and fiber-reinforced polymers (FRP). FRP poles are gaining wide acceptance for what they provide in terms of strength and durability, lack of maintenance and a high strength to weight ratio. Hybrid structures can combine the best properties of the materials used, where each part enhances the structure to provide a balanced structure. This study evaluates a hybrid structure composed of three main layers, an outer FRP shell, a hollow concrete core and an inner hollow steel tube, this whole system is to be utilized as a tapered utility pole. The outer FRP shell provides protection and enhances the strength of the pole, the concrete core provides stiffness, and the inner steel tube enhances the flexural performance while reducing the volume in consequence the weight of the structure compared to a fully filled pole. A new design for a 12-feet long hybrid FRP pole using finite element is presented in this paper. The design was based on a parametric study evaluating the effect of key-design parameters (i.e., the thickness of FRP, the volume and strength of the concrete, the thickness and diameter of the steel tube). Concrete strength affected the general performance of the pole, the decrease in concrete strength due to utilizing lightweight concrete was compensated with increasing the FRP pole thickness. For the same pole configuration, with incremental variation of the FRP thickness values from 3 mm to 7 mm up to the initial concrete cracking load, no significant variation of the pole top deflection was observed. However, at failure load the increase of FRP thickness from 3 mm to 7 mm decreased the ultimate tip deflection by 50%. New hybrid utility poles have the potential to be an interesting alternative solution to the conventional poles as they can provide better durability and mechanical performances.

This paper presents the application of a low-cost thick-shell nonlinear finite element analysis (NLFEA) procedure to estimate the punching shear resisting performance of reinforced concrete slab-column connections under variable connection shear stress conditions. Variation of connection stress conditions stems from columns with different cross section aspect ratios, different distributions of gravity loading conditions, and slabs constructed with significantly different planar reinforcement conditions in the orthogonal directions. In this regard, thirty-five isolated slab-column connection specimens presented in the literature were analyzed using a shell finite element-based analysis procedure and the results from these analyses were used to assess NLFEA model performance. All results were developed using a predefined set of material models and analysis parameters, defined on the basis of prior and unrelated validation studies, and were shown to provide good agreement with experimental findings without the need for calibration studies or the adoption of case-specific failure criteria. From the findings obtained, it was determined that the thick-shell NLFEA employed is suitable for estimating the punching shear response for slabs subjected to varied and highly non-uniform shear stresses within the connection regions and provided similar levels of precisions as that previously obtained for isolated slab-column connections constructed with idealized geometries and reinforcing conditions, subjected to idealized loading conditions.

In this study, a prestressed concrete girder bridge without plans and with severe levels of deterioration, located in Cali, Colombia, was load-tested to quantify, experimentally, its live-load behavior. The bridge consists of seven prestressed I-girders covered with a reinforced concrete deck, and four diaphragm beams. A geometric survey was performed to obtain the dimensions for a shell-based linear finite-element model (FEM) representing the bridge superstructure. In this survey, it was observed that the diaphragm beams in the span are geometrically inadequate to contribute to the structural system. Based on the experimental modal properties and the design regulations enforced at the time of bridge design and construction, a first update was made. Modifying the effective stiffness of selected elements to model girder deterioration, a second update was performed based on strain-gauge data from three load tests and visual inspection (VI) of the elements. The three models (basic, modal updated, and load-test/VI updated) were compared with the load distribution factor (DF) obtained from the load test and AASHTO distribution factor estimations. Visual inspection, dynamic characterization, and load testing response of this structure indicated severe deterioration of the girders and the absence of the effect of the diaphragms in the overall structural behavior. The results show that the AASHTO recommendations overestimate the LDF in comparison with the FEM without girder deterioration. When girder deterioration is included in the model, the LDFs change drastically, showing that AASHTO estimations are not in line with the experimental results. As such, for cases of bridges with severe levels of deterioration, it is recommended to use field data to estimate the distribution factors.

Current computational modeling approaches used to evaluate the impact-resisting performance of reinforced concrete infrastructure generally consist of high-fidelity modeling techniques which are expensive in terms of both model preparation and computation cost; thus, their application to real-word structural engineering problems remains limited. Further, modeling shear, erosion, and perforation effects presents as a significant challenge, even when using expensive high-fidelity computational techniques. To address these challenges, a simplified nonlinear modeling methodology has been developed. This paper focuses on this simplified methodology which employs a smeared-crack continuum material model based on the constitutive formulations of the Disturbed Stress Field Model. The smeared-crack model has the benefit of simplifying the modeling process and reducing the computational cost. The total-load, secant-stiffness formulation provides well-converging and numerically stable solutions even in the heavily damaged stages of the responses. The methodology uses an explicit time-step integration method and incorporates the effects of high strain rates in the behavioral modeling of the constituent materials. Structural damping is primarily incorporated by way of nonlinear concrete and reinforcement hysteresis models and significant secondorder mechanisms are considered. The objective of this paper is to present a consistent reinforced concrete modeling methodology within the context of four structural modeling procedures employing different element types (e.g., 2D frames, 3D thick-shells, 3D solids, and 2D axisymmetric elements). The theoretical approach common to all procedures and unique aspects and capabilities of each procedure are discussed. The application and verification of each procedure for modeling different types of large-scale specimens, subjected to multiple impacts with contact velocities ranging from 8 m/s (26.2 ft/s) to 144 m/s (472 ft/s), and impacting masses ranging from 35 kg (77.2 lb) to 600 kg (1323 lb), are presented to examine their accuracy, reliability, and practicality.

Carbon reinforced concrete (CRC) is a material composed of a high-performance concrete and a carbon reinforcement (textile grids, lamellas, rods). Composite materials with reinforcements of other fiber materials are called textile reinforced concrete (TRC). The investigations of CRC started more than 20 years ago and the continuous development as well as research findings have opened many fields of application. Today, the use of CRC includes the strengthening of reinforced concrete elements as well as the realization of new elements such as facades, shells and even bridges.

Some of these structures require knowledge of the fatigue behavior due to cyclic loading (e. g. bridges). In a collaborative project of the Institute of Structural Concrete of the RWTH Aachen University and the Institute of Concrete Structures of the TU Dresden, the uniaxial tensile fatigue behavior of two carbon textile reinforcement types was systematically investigated. The specimens were subjected up to 107 loading cycles and stress ranges up to 261 ksi (1,800 MPa). The influence of the maximum load and amplitude were investigated as well as fatigue curves for these two reinforcement types derived.