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The reinforcing members are often added on an existing structure to improve stiffness of the structure up to required level. In general, the design targets for the reinforcing members need to be allocated for their designs. However, since the members are additively designed, it is difficult to predict behavior of the reinforcing members and their influence on the existing structure. Therefore, allocating the design targets is challenging task, and the targets based on engineering experience and intuition can lead to the repetitive design cycles. This paper proposes a method for determining target stiffness of a reinforcing member which makes an existing structure achieve the required performances. To utilize individual models of an existing structure and the reinforcing members in a design, the system of equations of the assembled structure is decomposed by using a substructuring technique. Additional boundary conditions are imposed on the interfaces between the structure and members to ensure consistency between models, and the target stiffness of the member is defined by using the boundary conditions. The optimal target stiffness and design of the members are determined through the use of a multidisciplinary design optimization technique, analytical target cascading. This method is applied to a simple portal frame and a body-in-white with reinforcing member of a vehicle manufactured by Hyundai Motor Company. By using the optimal target stiffness, reinforcing member of any shape can be designed independently and at little cost, without access of the existing structure model.

Reinforced concrete (RC) structure design codes stipulate various design limits to prevent the brittle failure of members, as well as ensure serviceability. In the structural design of RC walls, the maximum shear strength is limited to prevent sudden shear failure due to concrete crushing before the yielding of shear reinforcement due to over-reinforcement. Despite the increase in wall shear strength provided by a compression strut, the maximum shear strength limit for walls in the ACI 318-19 Code is the same as the maximum torsional strength. Consequently, the shear strength of large-sized walls with high-strength concrete is limited to an excessively low level. The ACI 318-19, Eurocode 2, CSA-19, and JSCE-17 standards provide similar equations for estimating wall strength, but their maximum shear strength limits for walls are all different. In this study, experimental tests were conducted on nine RC wall specimens to evaluate the maximum shear strength. The main variables of the specimens were shear reinforcement ratio, compressive strength of concrete, and failure mode. The experimental results showed that the maximum load was reached after yielding of shear reinforcement, even when the shear reinforcement ratio was 1.5 times higher than the maximum shear reinforcement ratio specified in the ACI 318-19 code. In addition, the measured shear crack width of all specimens at the service load level was less than 0.42 mm (0.017 in.). The shear strength limits for walls in the current codes were compared using 109 experimental results failing in shear before flexural yielding or shear friction failure, assembled from the literature. The comparison indicated that the ACI 318-19 Code limit underestimates the maximum shear strength of walls, and it particularly underestimates the maximum shear strength of walls with high-strength concrete or barbell-shaped cross sections. Additionally, this study proposes an equation for estimating the maximum shear strength limit of walls based on the truss model. The proposed equation predicted the maximum shear strength of RC walls with reasonable accuracy. Keywords: maximum shear strength limit; over-reinforcement; reinforced concrete (RC) walls; shear failure.

Eleven large-scale reinforced concrete coupling beam specimens were tested under reversed cyclic displacements of increasing magnitude. The main variables included yield stress ([f.sub.y]) of the primary longitudinal reinforcement (Grade 80, 100, or 120 ksi [550, 690, or 830 MPa]), span-depth (aspect) ratio (1.5, 2.5, or 3.5), and layout of the primary longitudinal reinforcement (diagonal [D] or parallel [P]). Specimens had the same nominal concrete strength (8000 psi [55 MPa]) and cross section (12 x 18 in. [310 x 460 mm]) and were designed for nominal shear stresses of 8 [??] psi (0.67 [??] MPa) for D-type beams and 6[??] psi (0.5[??] MPa) for P-type beams. Transverse reinforcement was Grade 80 (550) in all but one beam (D120-2.5), which had Grade 120 (830) reinforcement. Test results show that, on average, D-type beams had chord rotation capacities in excess of 5%, 6%, and 7% for beams with aspect ratios of 1.5, 2.5, and 3.5, respectively. P-type beams with Grade 80 or 100 (550 or 690) longitudinal bars, tested only for an aspect ratio of 2.5, had chord rotation capacities of approximately 4%. Based on these results, the authors recommend permitting the use of high-strength steel, Grade 80 (550) and higher, in D-type and P-type coupling beams for earthquake-resistant design. The spacing of confining reinforcement should be limited to 5[d.sub.b] for [f.sub.y] = 80 ksi (550MPa) and 4[d.sub.b] for [f.sub.y] = 100 or 120 ksi (690 or 830MPa). Consistent with prior findings, the results show that deformation capacity is correlated with span-depth ratio and more sensitive to spacing of the confining reinforcement than to uniform elongation of the longitudinal reinforcement. Finally, the test results illustrate the effects of reinforcement grade on stiffness and energy dissipation of pseudo-statically loaded coupling beams. Keywords: chord rotation capacity; confining reinforcement; deformation capacity; force-deformation envelope; hoop spacing; reinforcement grade; reversed cyclic displacements.

As an important historical relic of human being, masonry pagoda is the great significance in the eastern and western architectural cultures. Most of the existing masonry pagodas in China which have been seriously damaged urgently need detailed structural safety assessment, repair and reinforcement. The paper choose a Chinese masonry pagoda as a case, conducted a series simulation analysis with Abauqs. Through numerical simulation, the seismic performance of the pagoda can be evaluated, which can not only predict the hidden danger and weak link in its structure, but also provide useful reference for the reinforcement and repair of the pagoda. It also adopts a very convenient 3D CAD method to quickly assess the seismic vulnerability of existing masonry pagoda according the reference.

Formula Society Automotive Engineer (FSAE) is an engineering competition for university students conducted by SAE International Organization that challenges students to build a mini-formula-style prototype car. Some factors affecting the vehicle performance are mass and torsional stiffness of the chassis. This study aims to optimize the existing competed vehicle chassis using a combination methods in Computer Aided Engineering (CAE): parametric and structural methods, which varies the dimensions, support bracing direction, and number of support bracing of frame structures. The design criteria were required to meet the competition regulations, a safety factor of more than 1.5, and a torsional stiffness to roll rate ratio of more than 6, with a specific torsional stiffness target of 48.82 – 60.08 Nm/deg/kg. In the optimization process, 30 chassis variations were tested. The S24 variation showed a significant increase in torsional stiffness and specific torsional stiffness. The S19 variation showed the most significant effect on the safety factor. At the end, the S12 chassis was selected as the lightest mass (31.125 Kg), with torsional stiffness 1,614.59 Nm/degree, specific torsional stiffness of 51.87 Nm/deg/Kg, safety factor of 1.54, and torsional stiffness to roll rate ratio of 6.31.

On 6 February 2023, two significant seismic events occurred in the southeastern region of Türkiye. The seismic activity, which was perceptible in numerous countries beyond Türkiye, resulted in a considerable number of fatalities. A considerable number of individuals lost their lives and were rendered homeless as a result of the disaster. Two of the most significant factors contributing to the occurrence of these tragedies are the magnitude of the earthquake and structural deficiencies. The present study is concerned with a detailed analysis of these two factors. This study initially considers the seismicity of the region where the earthquakes that occurred on 6 February 2023 took place, as well as the seismic characteristics of these earthquakes. Subsequently, the findings of the field studies conducted in Hatay, Adıyaman, Kahramanmaraş and Malatya, the cities where the earthquakes caused the most destruction, are presented. The objective of the field study is to ascertain the collapse patterns, structural damages and the factors influencing these damages in reinforced concrete structures in the region. The primary causes of damage to structures can be attributed to several factors, including the presence of a strong beam-weak column mechanism, the soft story-weak story mechanism, the pounding effect, the short column damage, the long cantilever and overhangs, the short beam damage, the buckling damage, the torsion effect, the quality of the materials, the insufficient transverse reinforcement, the compressive failure due to over-reinforcement, the corrosion effect, the damage to reinforced concrete shear walls, the infill wall damage, and the damage caused by the soil and foundation system. These causes have been evaluated and recommendations have been formulated to prevent structural damage.

This paper investigates the seismic performance of exterior beamcolumn 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 Grades 60, 80, or 100 (No. 420, 550, or 690) reinforcement in accordance with ACI 318-19 provisions for special moment frame joints, except for the provisions of joint shear and confinement. While ACI 318-19 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 318-19 to the Building Code Requirements for Concrete Structures in Taiwan. Keywords: axial load; beam-column joint; confinement; high-strength reinforcement; joint shear; reversed cyclic loading.

The present study demonstrates the feasibility of using longitudinal hybrid reinforcement in concrete columns in seismic zones. In this research, four concrete columns were constructed and subjected to quasi-static cyclic loading, featuring a combination of steel and glass fiber-reinforced polymer (GFRP) longitudinal reinforcement. Two reference columns were fabricated and reinforced in the longitudinal direction with steel bars. These columns had a 400 x 400 mm (15.8 x 15.8 in.) cross section and 1850 mm (72.8 in.) overall height. All the columns were reinforced with GFRP crossties and spirals in the horizontal direction. The variable parameters were the transverse reinforcement spacing, axial load ratio, and column configuration. The outcomes of this research clearly showed that reinforced concrete (RC) columns that are properly designed and detailed longitudinally with hybrid reinforcement (GFRP/steel) could achieve the drift limitation in building codes with no strength degradation. Further, these hybrid-RC columns displayed enhanced energy dissipation capacity, superior ductility, and improved post-earthquake recoverability compared to columns reinforced longitudinally with steel. The promising results of this study represent a step toward the use of longitudinal hybrid reinforcement in lateral-resisting systems. Keywords: design codes; ductility; energy dissipation capacity; glass fiber-reinforced polymer (GFRP); hybrid reinforcement; hysteresis response; quasi-static cyclic load; reinforced concrete (RC) columns; residual deformation; seismic load; stiffness degradation.

Abstract Background Creeping crises are slow-onset, complex disasters, and they increasingly receive attention for their impact on public health. Environmental stressors such as air pollution, climate change, or the impact of mining erode well-being over time. Effective governance is crucial to mitigate their long-term health impact. This study draws lessons from a creeping crisis in the Netherlands: decades of gas extraction in Groningen, resulting in earthquakes and burdensome government-led procedures for damage repair and preventive reinforcement. Methods Two panels were approached: the Groninger Panel in 2016-2024 (N > 6000) and a reinforcement-specific panel in 2024 (N > 700). Respondents were categorized by house damage history and reinforcement phase. Outcomes were: mental health (MHI-5), trust in institutions, and exposure to damage and governance. Results Respondents with repeated damage consistently report significantly lower MHI-5 scores and lower trust in national government. These disparities have persisted since 2016 but have not worsened since 2023. At the individual level, scores deteriorate during the reinforcement process. The results show that this process constitutes a major stressor, especially in early phases when respondents experience little support from institutions. Respondents expressed feelings of injustice, powerlessness, and political neglect. Conclusions This crisis illustrates how inadequate policy in creeping crises can become a structural health threat. Transparent, inclusive, human-centered governance is vital to restore trust and reduce long-term health disparities. While results from the Groninger Panel have contributed to a parliamentary inquiry and policies have been put in place to support Groningen citizens, health disparities have yet to be resolved. Key messages • In creeping crises, inadequate policy response can induce health disparities. • Monitoring of health impact, trust-building, and early support mechanisms are crucial.

In the context of growing environmental consciousness, the contemporary construction industry is placing significant emphasis on prolonging the functional lifespan of existing infrastructure. In the event of a modification in the utilisation of a building, an augmentation in the loads transferred to individual elements, or a deterioration in the condition of the structure due to wear and tear, it is often necessary to implement measures for structural reinforcement. The present paper sets out an analysis of the effectiveness of strengthening a steel column manufactured from SHS120×120×5. It was posited that four distinct reinforcement variants could be achieved by the implementation of additional stiffening elements through the process of welding. The efficiency analysis was conducted employing two distinct methodologies. The geometrical imperfection method is employed using the IDEAStatiCa Member 25.0.4 software, whilst the analytical method is implemented through the use of guidelines presented in the literature. It was demonstrated that all of the proposed solutions were capable of meeting the required column capacity when the loads were increased. A comparison was made between the values of the critical forces and the members’ stresses, determined by the selected methods. A substantial discrepancy was identified between the critical force values derived from linear buckling analysis and those calculated using elastic Euler theory. The following discourse herein delineates the primary advantages and limitations of the two aforementioned methods.