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The ACI 318-19 Building Code does not allow the use of headed bars larger than No. 11 (No. 36) due to insufficient experimental data. Thirty large-scale simulated beam-column joint specimens containing high-strength No. 11 (No. 36), No. 14 (No. 43), or No. 18 (No. 57) headed bars were tested to investigate the effects on anchorage strength of key factors, including bar stress at failure, bar size, bar spacing, embedment length, transverse reinforcement, concrete compressive strength, and loading condition. Specimens exhibited concrete breakout, side splitting, or a combination, with four exhibiting a shear-like failure. Anchorage of larger bars is noticeably influenced by joint shear demand and loading conditions. Descriptive equations developed based on 164 tests, accurately characterize anchorage strength for headed bars up to No. 18 (No. 57). They indicate that anchorage strength is proportional to concrete compressive strength to a power close to 0.2 and that the contribution of parallel ties for large headed bars is lower than that observed for smaller headed bars.

Flexural strength and ductility of exclusively bonded or unbonded steel prestressed concrete (PC) members are well covered and documented in the literature and codes of practice. However, current design methods are limiting the use of hybrid (i.e., a combination of unbonded and bonded steel and Fiber Reinforced Polymer (FRP)) tendons, particularly when using brittle material such as FRP tendons. In this paper, a general procedure for evaluating the nominal moment capacity and ductility of hybrid PC members was developed using the strain compatibility approach. The procedure is applicable for members with any combination of bonded or unbonded steel and FRP tendons. Using a capacity design approach based on strain compatibility, the ductility performance of several hybrid systems with different parameters was compared. The parameters included, among others, the level of “net tensile strain” in the tension reinforcement at nominal strength adopted in ACI 318-19 as a measure of ductility; concrete compressive strength; and the newly defined hybrid prestressing ratio (HPR). HPR represents the ratio of the moment contribution of the unbonded tendons to the total moment capacity of the member with hybrid tendons. Non-linear analysis was carried out to generate the entire load-deflection and moment-curvature responses of the different systems. The accuracy of the nonlinear analysis was verified by comparing with available experimental data and the analysis results were used to compare traditional curvature ductility measures of the various systems against the ductility measure specified in the ACI Building code. A design example is provided in Appendix A to illustrate the use of the strain compatibility approach.

The first edition of ACI 440.11 Building Code was published in September 2022, where some code provisions were either based on limited research or only analytically developed. Therefore, some code provisions, notably shear and development length in footings are difficult to implement. This study, via a design example, aims at a better understanding of the implications of code provisions in ACI 440.11-22 and compares them with ones in CSA S806-12, thereby highlighting a need for reconsiderations. An example of the footing originally designed with steel reinforcement was taken from the ACI Reinforced Concrete Design Handbook and redesigned with GFRP reinforcement as per ACI 440.11-22, and CSA S806-12. A footing designed as per ACI 440.11-22 requires a thicker concrete cross-section to satisfy shear requirements, however, when designed as per CSA S806-12 the required thickness becomes closer to that of the steel-reinforced concrete (RC) footing. The development length required for a GFRP-RC cross-section designed as per ACI 440.11-22 was 13% and 92% greater than that designed as per CSA S806-12 and ACI 318-19 respectively. Also, the reinforcement area required to meet detailing requirements is 170% higher than that for the steel-RC cross-section. Based on the outcomes of this study, there appears to be a need for reconsideration of some code provisions in ACI 440.11-22 to make GFRP reinforcement a viable option for RC members.

Several incidents of early deterioration of structures have been reported in literature; such incidents have a negative impact. Insufficiencies in the durability design may result from a possible absence of explicit guidelines in design codes and standards that establish a standardized language for building design, construction, and operation. Most design codes and standards, while providing a robust framework for structural capacity and serviceability, do not address durability design to a desirable degree. This study examines and critically reviews the durability design in three international codes: the American, British, and Eurocodes. The study revealed that the European and British standards have comparatively more precise and comprehensive durability provisions, whereas the American code has a larger scope for development. The study introduces a proposal for the improvement of durability design provisions in codes to provide beneficial examples that can assist in the update of upcoming editions of these codes.

Wall shear-strength equations reported in the literature and used in building codes are assessed using a comprehensive database of reinforced concrete wall tests reported to have failed in shear. Based on this assessment, it is concluded that mean values varied significantly, and coefficients of variation were relatively large (>0.28) and exceeded the target error for a code-oriented equation defined in a companion paper (Rojas-León et al. 2024). Therefore, a methodology employing statistical and machine-learning approaches was used to develop a new equation with a format similar to that currently used in ACI 318-19. The proposed equation applies to walls with rectangular, barbell, and flanged cross sections and includes additional parameters not considered in ACI 318-19, such as axial stress and quantity of boundary longitudinal reinforcement. Parameter limits—for example, on wall shear and axial stress—and an assessment of the relative contributions to shear strength are also addressed.