International Concrete Abstracts Portal

Coastal reinforced concrete bridges are critical infrastructures, yet they face significant threats from corrosion due to saline environments and extreme loads like wave-induced forces and seismic events. This state-of-the-art review examines the resilience of corrosion-damaged RC bridges under such conditions. It compiles advanced methodologies and technological innovations to assess and enhance durability and safety. Key highlights include synthesizing loss estimation models with advanced reliability methods for a robust resilience assessment framework. Analyzing catastrophic bridge failures and environmental deterioration, the review underscores the urgent need for innovative materials and protective technologies. It emphasizes advanced analytical models like Performance-Based Earthquake Engineering (PBEE) and Incremental Dynamic Analysis (IDA) to evaluate combined impacts. The findings advocate for engineered cementitious composites (ECC) and advanced sensor systems for improved real-time monitoring and resilience. Future research should focus on developing comprehensive resilience models accounting for corrosion, seismic, and wave-induced loads to enhance infrastructure safety and sustainability.

Lap splicing of longitudinal reinforcing bars in shear walls is often encountered in practice, and the transfer of forces in lap-spliced reinforcing bars to the surrounding concrete depends on the bond strength. Buildings with shear walls during an earthquake develop plastic hinges in the shear walls, particularly where the reinforcing bars are lap-spliced. Brittle failure is commonly observed in reinforcing bar lap-spliced shear walls, which needs to be minimized by choosing the appropriate percentage of lap-spliced reinforcing bars. Therefore, it is essential to address the detailing of the lap-spliced regions of reinforced concrete (RC) shear walls. Several seismic design codes provide guidelines on lap-spliced detailing in shear walls related to its location, length of lap-splice, confinement reinforcement, and percentage of reinforcing bars to be lap-spliced. In this study, the percentage of reinforcing bars to be lap-spliced at a section is examined with staggered lap-splicing of 100, 50, and 33% of longitudinal reinforcing bars, in addition to a control RC shear wall without lap-splicing. This study tested four half-scale RC shear walls with boundary element (BE), designed as per IS 13920 and ACI 318, under quasi-static reversed cyclic loading. From the experimental study, it is observed that the staggered lap splicing of reinforcing bars nominally reduces the performance of shear walls under cyclic load in terms of the reduced flexural strength, deformation capacity, energy dissipation, and ductility of the shear walls compared to the control shear wall without lap splicing. It is also observed that the unspliced reinforcing bars do not sustain the cyclic loading in staggered lap-splice after the post-peak. Current provisions of ACI 318, EC2, and IS 13920 recommend staggered lap-splice detailing in shear walls. However, from the current study, shear walls with different percentages of staggered lap splice show that the staggered lap-splice detailing in shear walls does not improve its seismic performance.

This research proposes a standardized arrangement of longitudinal reinforcement using Grade 690 MPa (100 ksi) high-strength steel and D32 (#10) or D36 (#11) large-diameter threaded bars to alleviate reinforcement congestion and construction difficulties. Four full-scale column specimens with the proposed standardized arrangement were tested using double-curvature lateral cyclic loading to examine their seismic performance. Test results showed that all the columns exhibited a combined axial and flexural failure mode, with ultimate drift ratios ranging from 4.07 to 5.98%, ratios of measured to nominal moment strength based on actual material strengths ranging from 1.18-1.51, and relative energy dissipation ratios satisfying the requirement of ACI 374.1-05. No shear or bond-splitting failures were observed. Based on the test data from this research and the literature, two modifications were proposed in the calculation of l_d to relax the requirement of 1.25l_d≤l_u/2 as required by ACI 318-19.

This paper investigates the seismic performance of exterior beam-column joints in special moment frames (SMFs) with varying axial load ratios. Cyclic testing of four additional specimens with an axial load ratio of 0.45 is compared with four companion specimens at 0.10. Each specimen was designed and constructed with Gr.60 (420), Gr.80 (550), or Gr. 100 (690) reinforcement in accordance with ACI CODE-318 provisions for special moment frame joints, except for the provisions of joint shear and confinement. While ACI CODE-318 tightens confinement requirements for SMF columns and joints, especially under high axial loads, this study reveals that increasing the axial load ratio benefits joint behavior. The study also demonstrates the feasibility of using high-strength reinforcement in exterior beam-column joints of SMFs, provided that appropriate modifications are made. The findings in this study have influenced modifications from ACI CODE-318 to the Building Code Requirements for Concrete Structures in Taiwan.

The present study investigated the contribution of slabs to the lateral load-carrying capacity of shear walls coupled with slabs. Cyclic lateral load tests were conducted on five two-story wall specimens at half scale. The test parameters included the thickness of the slab, the wall opening length, the use of punching shear reinforcement, and the use of parallel walls. The test results showed that, due to the slab effect, the strengths of the coupled wall specimens were 38 to 88% greater than the strength of walls without the slab effect. Furthermore, the initial stiffness of the specimens was significantly increased by the slab effect. During early loading, local failure of the slabs occurred at the wall-slab connection. However, the coupled walls exhibited ductile behavior up to a 2% drift ratio, without significant degradation of strength. Nonlinear finite element analysis was performed on the test specimens. Based on the results, the initial stiffness and effective stiffness of the walls and coupling slabs were evaluated for the seismic design of coupled walls.