Search Results (208)

The 2020 southern Puerto Rico earthquake sequence highlighted the severe seismic vulnerability of informally constructed two-story reinforced concrete (RC) houses. This study examines the failure mechanisms of these structures and assesses the effectiveness of first-floor RC shear-wall retrofitting. Nonlinear pushover and dynamic time–history analyses were performed using fiber-based distributed plasticity models for RC frames and nonlinear macro-elements for second-floor masonry infills, which introduced a significant inter-story stiffness imbalance. A bi-directional seismic input was applied using spectrally matched, near-fault pulse-like ground motions. The findings for the as-built structures showed that stiffness mismatches between stories, along with substantial strength and stiffness differences between orthogonal axes, resulted in concentrated plastic deformations and displacement-driven failures in the first story—consistent with damage observed during the 2020 earthquakes. Retrofitting the first floor with RC shear walls notably improved the performance, doubling the lateral load capacity and enhancing the overall stiffness. However, the retrofitted structures still exhibited a concentration of inelastic action—albeit with lower demands—shifted to the second floor, indicating potential for further optimization. Full article

The present research aims to the evaluation of the deformation capacity of existing reinforced concrete shear walls designed with past non-conforming seismic regulations. A refined analytical model (referred to as the Proposed Model) is presented for generating Load–displacement (P-d) curves for RC shear walls. The model is applicable to medium-rise walls designed with or without modern seismic provisions and incorporates shear effects in both deformation and strength capacity. The application of the Proposed Model is assessed through comparison with numerical models implemented in the widely accepted OpenSees platform. Specifically, two types of elements are examined: the widely used flexural element Force-Based Beam-Column Element (FBE) and the Flexure-Shear Interaction Displacement-Based Beam-Column Element (FSI), which accounts for the interaction between flexure and shear. The results of both analytical and numerical approaches are compared with experimental data from four RC shear wall specimens reported in previous studies. Full article

In order to enhance the seismic performance of existing masonry structures and optimize the thickness of the strengthening layer, ultra-high-performance concrete (UHPC) can be used as an enhancement material. Based on current concrete strengthening methods, the bearing capacity and seismic behavior of existing masonry structures strengthened with UHPC were investigated numerically. The effects of the strengthening layer thickness and reinforcement ratio on the structural strengthening results were analyzed numerically. The structural behaviors before and after an earthquake, with various strengthening methods, were compared and discussed. The results show that the ratio of axial resistance to shear resistance increases linearly with the resistance ratio. The seismic performance of damaged masonry walls can be improved by about 150% and 250% when 20 mm thick double-sided plain UHPC layers and 30 mm thick double-sided plain UHPC layers are used for strengthening, respectively. The axial compression ratio of masonry walls can be reduced by about 60–70% when double-sided plain UHPC layers are used for strengthening. Full article

Reinforced concrete structures often require retrofitting due to damage caused by natural disasters such as earthquakes, floods, or hurricanes; deterioration from aging; or exposure to harsh environmental conditions. Retrofitting strategies may involve adding new structural elements like shear walls, dampers, or base isolators, as well as strengthening the existing components using methods such as reinforced concrete, steel, or fiber-reinforced polymer jacketing. Selecting the most appropriate retrofit method can be complex and is influenced by various factors, including initial cost, long-term maintenance, environmental impact, and overall sustainability. This study proposes utilizing an artificial neural network (ANN) to predict sustainable and cost-effective seismic retrofit solutions. By training the ANN with a comprehensive dataset that includes jacket thickness, material specifications, reinforcement details, and key sustainability indicators (economic and environmental factors), the model was able to recommend optimized retrofit designs. These designs include ideal values for jacket thickness, concrete strength, and the configuration of reinforcement bars, aiming to minimize both costs and environmental footprint. A major focus of this research was identifying the optimal number of neurons in the hidden layers of the ANN. While the number of input and output neurons is defined by the dataset, determining the right configuration for hidden layers is critical for performance. The study found that networks with one or two hidden layers provided more reliable and efficient results compared to more complex architectures, achieving a total regression value of 0.911. These findings demonstrate that a well-tuned ANN can serve as a powerful tool for designing sustainable seismic retrofit strategies, helping engineers make smarter decisions more quickly and efficiently. Full article

This study addresses a critical gap in blast-resistant design by investigating the influence of axial compression ratio—a previously underexplored parameter—on the dynamic response of reinforced concrete (RC) shear walls under close-in explosions. While existing research has focused on conventional loading scenarios, the interplay between axial compression and blast effects remains poorly understood, despite its practical significance for structural safety in high-risk environments. Through a combined experimental and numerical approach, three half-scale RC shear walls were tested under blast loading, complemented by simulations analyzing key parameters (aspect ratio, axial compression ratio, boundary conditions, and charge weight). The results demonstrate that a moderate axial compression ratio (around 0.3) enhances structural stiffness and reduces displacement, effectively helping to control wall damage. Boundary conditions were also found to affect failure modes: walls with stiffer end restraints exhibited reduced deformation but more brittle cracking. Lower aspect ratios (i.e., wider walls) improved blast resistance, and peak displacement progressively increased with the charge weight. These findings provide actionable insights for optimizing RC shear wall design in blast-prone infrastructures, balancing ductility and load capacity. By linking theoretical analysis to practical design criteria, this study advances blast-resistant engineering solutions. Full article

The connection zones between precast concrete composite slabs and composite walls commonly experience severe reinforcement conflicts due to protruding rebars, significantly reducing construction efficiency. To address this, a novel slotted concrete composite slab–composite shear wall (SCS-CW) connection without protruding rebars is proposed in this study. In this novel connection, rectangular slots are introduced at the ends of the precast slabs, and lap-spliced reinforcement is placed within the slots to enable force transfer across the joint region. To investigate the static performance of SCS-CW connections, four groups of connection specimens were designed and fabricated. Using the structural detailing of the connection zone as the variable parameter, the mechanical performance of each specimen group was analyzed. The results show that the specimens demonstrated bending failure behavior. The key failure modes were yielding of the longitudinal reinforcement in the post-cast layer, yielding of the lap-spliced reinforcement, and concrete crushing at the precast slab ends within the plastic hinge zone. Compared to composite slab–composite wall connections with protruding rebars, the SCS-CW connections demonstrated superior ductility and a higher load-carrying capacity, satisfying the design requirements. Additionally, it was revealed that the anchorage length of lap-spliced reinforcement significantly affected the ultimate load-carrying capacity and ductility of SCS-CW connections, thus highlighting anchorage length as a critical design parameter for these connections. This study also presents methods for calculating the flexural bearing capacity and flexural stiffness of SCS-CW connections. Finally, finite element modeling was conducted on the connections to further investigate the influences of the lap-spliced reinforcement quantity, diameter, and anchorage length on the mechanical performance of the connections, and corresponding design recommendations are provided. Full article

In recent years, frequent vehicle–bridge pier collision accidents have posed a serious threat to people’s economic and life security. In order to avert the impairment of reinforced concrete bridge piers (RCBPs) under the impact of vehicles, three kinds of Mg–Al alloy AlSi10Mg anti-collision structures designed by selective laser melting (SLM) printing were tested by the numerical simulation method in this study: an ultra-high performance concrete (UHPC) anti-collision structure, a bio-inspired honeycomb column thin-walled structure (BHTS) buffer interlayer, and a UHPC–BHTS composite structure were used to reduce the damage degree of RCBPs caused by vehicle impact. In accordance with the prototype configuration of the pier, a scaled model with a scale ratio of 1:10 was fabricated. Three anti-collision structures were installed on the reinforced concrete (RC) column specimens for the steel ball impact test. The impact simulation under low-energy and high-energy input was carried out successively, and the protective effect of the three anti-collision devices on the RC column was comprehensively evaluated. The outcomes demonstrate that the BHTS buffer interlayer and the UHPC–BHTS composite structure are capable of converting the shear failure of RC columns into bending failure, thereby exerting an efficacious role in safeguarding RC columns. The damage was evaluated under all impact conditions of BHTS and UHPC–BHTS composite structures, and the RC column only suffered slight damage, while the RC column without protective measures and the RC column with the UHPC anti-collision structure alone showed serious damage and collapse behavior. This approach can offer a valuable reference for anti-collision design within analogous projects. Full article

Currently, seismic-resistant design is carried out by applying codes that are periodically updated based on research findings and lessons learned from major seismic events. In the case of buildings located on sloping terrains and those composed of reinforced concrete shear walls, there is a notable lack of specific design provisions in existing standards. For this reason, the methodology outlined in FEMA P695 was applied in the present study, with the aim of validating the response reduction factor used for designing this type of structure in Chile. Additionally, other parameters that allow for the evaluation of design performance or serve as complementary indicators—such as ductility, the overstrength factor, and the displacement amplification factor—were determined. To conduct this study, a series of archetype buildings were designed, varying the slope inclination from 0° to 45°. The results show that, although the current design approach ensures safety, it is necessary to specify different design parameters for the directions parallel and orthogonal to the slope in order to optimize the seismic performance of the buildings. Full article

Shear walls, integrated into conventional reinforced concrete (RC) moment-resisting frame systems (RC frame–shear wall building), have proven to be effective in improving the structural performance and reliability of buildings; however, the seismic behavior of the building depends directly on the location of these elements. For this reason, this paper evaluates the structural reliability of ten medium-rise RC buildings designed based on the Mexico City Building Code, considering different shear wall configurations. With the aim to estimate and compare the seismic reliability, the buildings are modeled as complex 3D structures via the OpenSees 3.5 software, which are subjected to different ground motion records representative of the soft soil of Mexico City scaled at different intensity values in order to compute incremental dynamic analysis (IDA). Furthermore, the parameter used to estimate the reliability is the maximum interstory drift (MID), which is obtained from the incremental dynamic analysis in order to assess the structural fragility curves. Finally, the structural reliability estimation is computed via probabilistic models by combining the fragility and seismic hazard curves. It is concluded from the results that the structural reliability is maximized when shear walls are symmetrically distributed. On the other hand, the configuration with walls concentrated in the center of the building tends to oversize the frames to reach a reliability level comparable to that of symmetrical arrangements. Full article

Reinforced concrete began replacing traditional masonry construction in the early 20th century, yet hybrid buildings combining unreinforced masonry (URM) walls with concrete slabs remain prevalent in Istanbul. Understanding their seismic behavior is critical for risk mitigation and heritage preservation. This study investigates a seven-story masonry residential building with cast-in-place reinforced concrete slabs constructed in 1953. The assessment involved non-destructive inspections, double flat-jack and shear tests, and geophysical site surveys. A finite element model was developed using Midas Gen software v2020 and analyzed through linear response spectrum and nonlinear pushover analyses based on TBSC-18 and SRMGHS-17. The modulus of elasticity ranged from 200.2 MPa to 1062.2 MPa, and bed joint shear strength varied between 0.50 MPa and 0.79 MPa. The building satisfied inter-story drift criteria for limited damage (SL-3), controlled damage (SL-2), and pre-collapse (SL-1). However, it failed to meet the shear force requirements at all levels. Pushover analysis revealed ultimate lateral capacities of 11,997 kN in the x-direction and 16,209 kN in the y-direction. The findings highlight the shear vulnerability of such hybrid systems and underscore the importance of combining experimental characterization with numerical modeling to develop effective retrofitting strategies. Full article

Concrete sandwich wall panels (CSWPs) have been constructed since the early 1900s using various wythe connectors, panel geometries, and construction methods to create a structurally and thermally efficient system. Initially, thermal bridging hindered thermal efficiency due to the concrete connections and steel bars used to transfer interface forces between the concrete wythes. This issue was mitigated with the advent of polymer connectors, now widely used in the precast and tilt-up industries. As a result, CSWPs now offer buildings an efficient envelope, aiding in energy savings and reducing the need for additional construction materials and therefore contributing to the construction industry’s sustainability goals. This paper examines the current state of the practice in CSWP construction, focusing on CSWP’s construction methods, sustainability, material selection, and design processes. This manuscript delves into the history of CSWPs and showcases projects ranging from housing to industrial applications. Moreover, the materials and hardware popularly used in their construction are reviewed from the practicing engineer and researcher’s point of view and other aspects, such as environmental, architectural, and structural design, are presented. The most popular construction methods and approaches when precasting these panels on- or off-site and their associated challenges are also presented. Lastly, current deficiencies in CSWP design and construction are outlined and future directions for research and practice are suggested to advance this field further. Full article

Fiber-reinforced polymers (FRPs) are effective for strengthening masonry walls. Debonding at the polymer–masonry interface is a major concern, requiring further investigation into interface behavior. This study utilizes detailed micro-modeling finite element (FE) analysis to predict failure mechanisms and analyze the behavior of brick masonry walls strengthened with externally bonded carbon fiber-reinforced polymer (CFRP) under in-plane loading. The research investigates three CFRP strengthening configurations (X, I, and H). The FE model incorporates the nonlinear behavior of brick masonry components using the Concrete Damage Plasticity (CDP) model and uses a cohesive interface approach to model unit–mortar interfaces and the bond joints between masonry and CFRPs. The results demonstrate that diagonal CFRP reinforcement enhances the ductility and capacity of masonry wall systems. The FE model accurately captures the crack propagation, fracture mechanisms, and shear strength of both unreinforced and reinforced walls. The study confirms that the model can reliably predict the structural behavior of these composite systems. Furthermore, the study compares predicted shear strengths with established design equations, highlighting the ACI 440.7R-10 and CNR-DT 200/2013 models as providing the most accurate predictions when compared to experimental results. Full article

Performance-based seismic design (PBD) has emerged as a key approach for rationalizing prescriptive code provisions and improving the explicit assessment of structural performance. In Chile, where reinforced concrete shear wall buildings are the predominant structural typology, evaluating their seismic response beyond traditional linear methodologies is crucial. This study assesses the seismic performance of a representative Chilean shear wall residential building using the ACHISINA manual’s performance-based seismic design framework. A nonlinear static (pushover) analysis is performed to verify compliance with prescribed design criteria, incorporating capacity design principles and a moment envelope approach to prevent premature yielding in upper stories. The results confirm that the building meets the performance objectives for both Immediate Occupancy and Additional Deformation Capacity limit states. The application of capacity design effectively controls shear demand, preventing brittle failure, while the flexural design ensures the formation of the yielding mechanism (plastic hinge) at the intended critical section. Additionally, the study highlights the limitations of pushover analysis in capturing higher-mode effects and recommends complementary nonlinear time-history analysis (NLTHA) for a more comprehensive assessment. The computed response reduction factors exceed those used in the prescriptive design, suggesting a conservatively safe approach in current Chilean practice. This research reinforces the need to integrate performance-based methodologies into Chilean seismic design regulations, particularly for shear wall structures. It provides valuable insights into the advantages and limitations of current design practices and proposes improvements for future applications. Full article

This paper proposes a hybrid steel plate–bolt dry and wet jointing method, where the dry jointing part is a steel plate–bolt connector joint and the wet jointing part is a cast-in-place concrete. The novel precast concrete shear wall (PCW) combines the advantages of both dry and wet connections. A steel plate–bolt dry–wet hybrid connection shear wall model was developed using the finite element method, and a low circumferential reciprocating load was applied to the PCW. By analyzing the force and deformation characteristics of the wall, the results showed that the failure mode of novel PCWs was bending-shear failure. Compared to the concrete wall (CW), the yield load, peak load, and ductile displacement coefficient were 6.55%, 7.56%, and 21.49% higher, respectively, demonstrating excellent seismic performance. By extending the wall parameters, it was found that the increased strength of the novel PCW concrete slightly improved the load-bearing capacity, and the ductility coefficient was greatly reduced. As the axial compression ratio increased from 0.3 to 0.4, the wall ductility decreased by 22.85%. Increasing the reinforcement rate of edge-concealed columns resulted in a severe reduction in ultimate displacement and ductility. By extending the connector parameters, it was found that there was an increased number of steel joints, a severe reduction in ductility, enlarged distribution spacing, weld hole plugging and bolt yielding, reduced anchorage performance, and weakening of the steel plate section, which reduced the load-bearing capacity and initial stiffness of the wall, with little effect on ductility. Full article

Textile-reinforced alkali-activated mortar (TRAAM) is a composite material that is characterized by a strain- or deflection-hardening response under tension or flexure, respectively, as well as by a good bond with concrete and masonry substrates. Owing to comparable or even superior mechanical performance compared to “conventional” cement- or lime-based textile-reinforced mortar (TRM) systems and its potentially eco-friendly energy and environmental performance, TRAAM has been incorporated to retrofitting schemes. The current article reviews the studies that investigate TRAAM as a strengthening overlay for masonry and concrete members. This article focuses on the mechanical performance of the strengthened members, which, where possible, is also compared with that of members strengthened with conventional TRM systems. It is concluded that TRAAM can enhance the flexural and shear capacity of masonry and concrete members, while it can also upgrade the compression strength and seismic response of concrete members. In addition, it is concluded that the effectiveness of TRAAM can be comparable with that of “conventional” TRM systems. The combination of TRAAM with thermal insulation boards has also been proposed for structural and energy upgrading of masonry walls. Furthermore, TRAAM can be a promising solution for increasing the fire resistance of strengthened masonry members. However, research on the long-term performance of TRAAM, including durability, creep, and shrinkage, is still limited. Finally, the lack of established standards for TRM retrofitting is more evident for TRAAM applications. Full article