In determining the shear capacity of reinforced concrete beams, current codes do not provide any calculation method to evaluate the influence of web horizontal reinforcement, although they exist as structural reinforcements (or skin reinforcement). The present paper comprises results of 11 reinforced concrete beams in an effort to investigate the influence of web horizontal reinforcement on the shear behavior of reinforced concrete beams. The primary design variables are the shear-span-depth ratio, different reinforcement ratio of stirrups and web horizontal reinforcement. Influence of web horizontal reinforcement on crack patterns and failure mode was studied. It was found that web horizontal reinforcement can increase the shear capacity of the beams and restrain growth of inclined cracks effectively. Test results are very valuable, as very few references of shear tests can be found focusing on the effect of web horizontal reinforcement on the shear capacity of the beams.

A mechanical model recently developed for the shear strength of slender reinforced concrete beams with and without shear reinforcement is presented and extended to elements with uniformly distributed loads, specially focusing on practical design and assessment in this paper. The shear strength is considered to be the sum of the shear transferred by the concrete compression chord, along the crack, due to residual tensile and frictional stresses, by the stirrups and, if they exist, by the longitudinal reinforcement. Based on the principles of structural mechanics simple expressions have been derived separately for each shear transfer action and for their interaction at ultimate limit state. The predictions of the model have been compared to those obtained by using the EC2, MC2010 and ACI 318-08 provisions and they fit very well the available experimental results from the recently published ACI-DAfStb databases of shear tests on slender reinforced concrete beams with and without stirrups. Finally, a detailed application example has been presented, obtaining each contributing component to the shear strength and the assumed shape and position of the critical crack.

In T-beams the force transfer from the web into the flange has to be studied. The general design procedure is based on a strut-and-tie (or a stress field) model which comprises spreading compressive and transverse tensile forces. As is known, strut-and-tie models represent the force flow within a structural member at ultimate. This procedure is sufficient for design purposes and in general, leads to safe results. For the assessment of a structure it may be worthwhile to improve the accuracy. For this purpose both web and flange have to be looked at more in detail. An advanced method for the analysis of webs in shear is the Generalized Stress Field Approach [1]. This approach can be utilized for treating flanges, where the classical assumptions have to be adapted; in particular by considering the strain dependence of the concrete compressive strength and thus, defining a representative strain value. In the present contribution background and details of these aspects are given, and the corresponding calculation procedure is described. Theoretical results are compared with experimental data and show a reasonably good agreement. However, as the number of sufficiently documented tests is very limited no concluding findings are attained.

This paper presents an experimental study of shear-governed reinforced concrete columns subjected to different loading rates. Four typical short columns were tested cyclically with loading rate of 0.05, 1, 3, and 5 Hz, simulating seismic load. Test result indicated that the loading rate does not affect the column behavior when the rate is up to 5 Hz. Furthermore, Carbon Nano-Fiber Aggregates (CNFAs) were utilized as internal sensors to detect the damage in the column. The test result shows that the CNFAs work well sensing the structural behavior. The CNFA output was further quantitatively correlated to the structural damage level. Finally, a finite element analytical model was constructed to describe the behavior of short columns with shear failure. The analytical model successfully modeled the cyclic loading test results.

Normal strength prestressed concrete I-girders are commonly used as the primary superstructure components in highway bridges. However, shear design guidelines for high strength PC girders are not available in the current structural codes. Recently, ten 7.62 m (25 feet) long girders made with high strength concrete were designed, cast, and tested at the University of Houston (UH) to study the ultimate shear strength and the shear concrete contribution (V_c) as a function of concrete strength ({f^{\prime }}_{\mathrm{c}}). A simple semi-empirical set of equations was developed based on the test results to predict the ultimate shear strength of prestressed concrete I-girders. The UH-developed set of equations is a function of concrete strength (\sqrt{{f^{\prime }}_{\mathrm{c}}}), web area (b_wd), shear span to effective depth ratio (a/d), and percentage of transverse steel (ρ_t). The proposed UH-Method was found to accurately predict the ultimate shear strength of PC girders with concrete strength up to 117 MPa (17000 psi) ensuring satisfactory ductility. The UH-Method was found to be not as overly conservative as the ACI-318 (2011) code provisions, and also not to overestimate the ultimate shear strength of high strength PC girders as the AASHTO LRFD (2010) code provisions. Moreover, the proposed UH-Method was found fairly accurate and not exceedingly conservative in predicting the concrete contribution to shear for concrete strength up to 117 MPa (17000 psi).

This manuscript discusses the design parameters that potentially affect the lateral seismic response of segmental precast post-tensioned bridge piers. The piers consist of precast circular cross section segments stacked one on top of the other with concentric tendons passing through ducts made in the segments during casting. The bottommost segments of the piers were encased in steel tubes to enhance ductility and minimize damage. An FE model was used to investigate different design parameters and how they influence the lateral force – displacement response of the piers. Design parameters investigated included the initial post-tensioning stress as a percentage of the tendon yield stress, the applied axial stresses on concrete due to post-tensioning, pier aspect ratios, construction details, steel tube thicknesses, and internal mild steel rebar added as energy dissipaters. Based on the data presented, an initial tendon stress in the range of 40%-60% of its yield stress and initial axial stress on concrete of approximately 20% of the concrete’s characteristic strength is appropriate for most typical designs. These design values will prevent tendon yielding until lateral drift angle reaches approximately 4.5%. Changing the steel tube thickness, height, or a combination of both proved to be an effective parameter that may be used to reach a target performance level at a specific seismic zone.

Currently the design scheme of precast hollow concrete bridge piers will be adopted in bridge design in China, but there is no code including specific design details of precast segmental piers in high seismic risk area. For comparative study of seismic performance of the hollow bridge piers which had different design details, six specimens of hollow section bridge pier were designed and tested. The specimens consist of the monolithic cast-in-place concrete bridge pier, precast segmental prestressed pier with cast-in-place joint and precast segmental concrete bridge pier with dry joints. Results show that all specimens have good displacement capacity. The bridge pier with bonded prestressed strands exhibits better energy dissipation capacity and higher strength. The un-bonded prestressed strand bridge pier displays less residual plastic displacement and energy dissipation capacity. The bridge pier with both bonded prestressed strands at the edge of the section and un-bonded in the center of the section not only exhibits more ductility capacity and less residual plastic displacement, but also shows better energy dissipation capacity. Compared with experimental results of prestressed bridge columns, analytical result demonstrates the developed numerical analysis model would provide the reasonable and accurate results.

This paper presents the results of nonlinear finite element analyses conducted on stainless steel shear links. Stainless steels are attractive materials for seismic fuse device especially for corrosion-aware environment such as coastal regions because they are highly corrosion resistant, have good ductility and toughness properties in combination with low maintenance requirements. This paper discusses the promising use of AISI 316L stainless steel for shear links as seismic fuse devices. Hysteresis behaviors of four stainless steel shear link specimens under reversed cyclic loading were examined to assess their ultimate strength, plastic rotation and failure modes. The nonlinear finite element analysis results show that shear links made of AISI 316L stainless steel exhibit a high level of ductility. However, it is also found that because of large over-strength ratio associated with its strain hardening process, mixed shear and flexural failure modes were observed in stainless steel shear links compared with conventional steel shear links with the same length ratio. This raises the issue that proper design requirements such as length ratio, element compactness and stiffener spacing need to be determined to ensure the full development of the overall plastic rotation of the stainless steel shear links.

Fire resistance rating of light gauge steel frame (LSF) wall systems is obtained from fire tests based on the standard fire time-temperature curve. However, fire severity has increased in modern buildings due to higher fuel loads as a result of modern furniture and light weight constructions that make use of thermoplastics materials, synthetic foams and fabrics. Some of these materials are high in calorific values and increase both the spread of fire growth and heat release rate, thus increasing the fire severity beyond that of the standard fire curve. Further, the standard fire curve does not include a decay phase that is present in natural fires. Despite the increasing usage of LSF walls, their behavior in real building fires is not fully understood. This paper presents the details of a research study aimed at developing realistic design fire curves for use in the fire tests of LSF walls. It includes a review of the characteristics of building fires, previously developed fire time-temperature curves, computer models and available parametric equations. The paper highlights that real building fire time-temperature curves depend on the fuel load representing the combustible building contents, ventilation openings and thermal properties of wall lining materials, and provides suitable values of many required parameters including fuel loads in residential buildings. Finally, realistic design fire time-temperature curves simulating the fire conditions in modern residential buildings are proposed for the testing of LSF walls.

Rock mass classification system is very suitable for various engineering design and stability analysis. JH classification method is confirmed by Japan Highway Public Corporation that this method can figure out either strength or deformability of rock mass, further appropriating the amount of rock bolts, thickness of shotcrete, and size of pitch of steel ribs just after the blasting procedure. Based on these advantages of JH method, in this study, according to data of five deep and long tunnels in Iran, two equations for estimating the value of JH method from Q and RMR classification systems were developed. These equations as a new method were able to optimize the support system for Q and RMR classification systems. From JH classification and its application in these case studies, it is pointed out that the JH method for the design of support systems in underground working is more reliable than the Q and RMR classification systems.

The present paper examines the evaluation of liquefaction potential of an earth dam foundation in Tunisia. The assessment of soil liquefaction was made using deterministic and probabilistic simplified procedures developed from several case histories. The data collected from the field investigation performed before and after the vibrocompaction are analyzed and the results are reported. The obtained results show that after vibrocompaction, a significant improvement of the soil resistance reduces the liquefaction potential of the sandy foundation. Indeed, in the untreated layers, the factor of safety FS drops below 1 which means that the soil is susceptible for liquefaction. However, in the compacted horizons, the values of FS exceed the unit which justifies the absence of liquefaction hazard of the foundation.