•An innovative and practical seismic retrofit method is proposed.•The method is based on a two-dimensional enlargement of the beam–column joint using steel angles that are mounted using prestressed ...cross-ties.•Seven half-scale external RC beam–column joints were subjected to lateral cyclic loading of increasing amplitudes.•The proposed method was shown to significantly enhance the seismic capacity of the non-seismically detailed joints.•The proposed retrofit method relocated the plastic hinge from the column face to outside of the joint panel.
Reinforced concrete (RC) structures that were built prior to the 1970s generally do not meet current seismic design requirements, especially in terms of reinforcement details. An innovative and practical seismic retrofit method is proposed for non-seismically detailed external beam–column joints of existing concrete structures, based on a two-dimensional enlargement of the beam–column joint using steel angles that are mounted using prestressed cross-ties. Seven half-scale external RC beam–column joints were subjected to lateral cyclic loading of increasing amplitudes. The tested specimens comprised of three control units and four retrofitted units. The test results confirmed that the proposed retrofit method not only resulted in relocation of beam plastic hinges to outside the joint panel zone but also improved the bond between the longitudinal beam and column tension reinforcement and concrete in the joint panel zone. The proposed method was shown to significantly enhance the seismic capacity of the joints, in terms of strength, stiffness, energy dissipation and ductility capacity.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Engineering design problems are often multi-objective in nature, which means trade-offs are required between conflicting objectives. In this study, we examine the multi-objective algorithms for the ...optimal design of reinforced concrete structures. We begin with a review of multi-objective optimization approaches in general and then present a more focused review on multi-objective optimization of reinforced concrete structures. We note that the existing literature uses metaheuristic algorithms as the most common approaches to solve the multi-objective optimization problems. Other efficient approaches, such as derivative-free optimization and gradient-based methods, are often ignored in structural engineering discipline. This paper presents a multi-objective model for the optimal design of reinforced concrete beams where the optimal solution is interested in trade-off between cost and deflection. We then examine the efficiency of six established multi-objective optimization algorithms, including one method based on purely random point selection, on the design problem. Ranking and consistency of the result reveals a derivative-free optimization algorithm as the most efficient one.
•Multi-objective optimization (MOO) approaches in general and in Reinforced Concrete (RC) structures are reviewed.•A novel multi-objective model is developed for the optimal design of RC beams.•A set of algorithms are examined and compared through numerical testing.•This paper enlightens the merits of advanced MOO methods in structural engineering problems.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
4.
Experimental tests of steel double-type balcony connections Solarczyk, Maciej Tomasz; Piotrkowski, Paweł; Niedostatkiewicz, Maciej
Czasopismo techniczne : organ Towarzystwa Politechnicznego,
01/2024, Volume:
121, Issue:
1
Journal Article
Peer reviewed
Open access
This paper presents an analysis and results of experimental tests of full-scale prefabricated balcony sets with dimensions (width × length × height): 2.0 m × 2.78 m × 0.186 m (in a slope to 0.17 m). ...The sets consist of reinforced concrete slabs (balcony and ceiling) connected with each other with double-type balcony connections. The paper analyses the impact of variable parameters on the load bearing capacity of the elements. Additionally, an overview of current scientific and technical papers in the field of balcony connections is provided.
Experimental tests of steel double-type balcony connections Solarczyk, Maciej Tomasz; Piotrkowski, Paweł; Niedostatkiewicz, Maciej
Czasopismo techniczne : organ Towarzystwa Politechnicznego,
01/2024, Volume:
121, Issue:
1
Journal Article
Peer reviewed
Open access
This paper presents an analysis and results of experimental tests of full-scale prefabricated balcony sets with dimensions (width × length × height): 2.0 m × 2.78 m × 0.186 m (in a slope to 0.17 m). ...The sets consist of reinforced concrete slabs (balcony and ceiling) connected with each other with double-type balcony connections. The paper analyses the impact of variable parameters on the load bearing capacity of the elements. Additionally, an overview of current scientific and technical papers in the field of balcony connections is provided.
The article presents a brief analysis of the experience of developing standards for the design of reinforced concrete structures in the Republic of Belarus. The principles on the basis of which these ...norms were developed are considered. The advantages and disadvantages of using European design standards EN 1992-1-1 of various generations, as well as fib Model Codes are shown.
•Numerical analysis of RC columns, beams, walls under fires with cooling phases.•Effect of thermal wave on structural stability is quantified.•Slower cooling rates increase propensity to fail after ...the peak fire temperature.•RC beams’ stability can be linked to reinforcement maximum reached temperature.•RC columns and walls’ behavior is more complex and requires thermal-structural analysis.
Fire exposed structures may collapse during or after the fire decay phase, with risks for building occupants and firefighters; yet, understanding of the effects of the fire decay phase on structural loadbearing capacity remains limited. This paper describes a numerical investigation on the behavior of reinforced concrete columns, beams, and walls under natural fires including cooling down phases. Finite element models are benchmarked against experiments capturing the behavior during heating. The models are then used to simulate the structural response of the concrete members under fires with various cooling rates and load ratios. The analyses capture the irreversibility of material properties through tracing of the temperature history in the structure. The results show that temperatures and deformations continue increasing after the end of the fire heating phase. As a result, concrete columns, beams, and walls may fail during the cooling phase. Faster cooling rates reduce the likelihood of failure in cooling. For beams, failure can be inferred from the maximum reinforcement temperature reached throughout the fire, but for columns and walls a thermal–mechanical analysis of the member throughout the fire history is needed. A relationship is proposed to evaluate the burnout resistance from the fire resistance rating and cooling rate. The presented numerical method allows assessing the structural stability throughout a fire event, an important requirement for designing a fire resilient built environment.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•A cohesive approach to simulate crack propagation in RC specimens is used.•An embedded truss model to capture concrete/rebar interaction is used.•Crack width and crack spacing in RC structural ...elements are accurately predicted.•Comparisons with experiments show the effectiveness of the proposed fracture model.
The cracking behavior analysis, in terms of crack spacing and crack width prediction, is essential to assess the damage and durability of a reinforced concrete (RC) structure. However, available numerical models cannot give satisfactory results in the cracking prediction due to the continuum representation of the concrete material often adopted in the numerical framework. Based on the cohesive finite element method, an interelement fracture model has been proposed here to investigate the cracking behavior, as well as its influence on the load-carrying capacity, of RC structural elements under static loading conditions. This fracture model is employed together with an embedded truss model for the rebars allowing them to be crossed by the cracks. Cracking analyses are performed on RC members subjected to tension and flexural loads. Comparisons with available experimental and numerical results have highlighted the effectiveness of the proposed model to investigate the cracking behavior in RC structures.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Material, mechanical, and thermomechanical properties of SMAs are compared.•A systematic review was conducted for the application of SMAs to existing and new RC structures.•Guidance is provided for ...the selection of SMA types and characteristics that are most suitable for a particular strengthening purpose.•The benefits and drawbacks of strengthening with SMAs over other advanced materials are discussed.•Challenges, unresolved issues, and future research opportunities in the use of SMAs for strengthening RC structures are presented.
The degradation of reinforced concrete (RC) structural components owing to aging mechanisms and extreme loading events can cause significant performance and safety concerns. Among the available alternatives for restoring such components, shape memory alloys (SMAs) exhibit unique properties, including the recovery of inelastic strain upon unloading (superelasticity) and/or heating (shape memory effect, SME). Particularly, the superelasticity and SME of SMAs can be applied to reduce permanent deformations and incorporate self-centering behavior into RC structures. Furthermore, the addition of SMAs can enhance the strength and stiffness of RC structures, enabling them to resist high load intensities with less damage. Despite the variety of investigations conducted on the structural applications of SMAs, the existing literature lacks a holistic review of the current progress, main findings, potential limitations, and future prospects of SMAs for the strengthening of existing RC structures and the design of new ones. Furthermore, comprehensive guidance is missing for selecting the SMA types and characteristics most suitable for a particular strengthening/self-centering application. To address the identified fundamental and practical gaps, we performed a detailed review of the applications of SMAs in RC beams, columns, beam-column joints, and shear walls. The identified applications were explored from the perspective of the self-centering, crack recovery, strength enhancement, confinement, and shear strengthening of existing and new RC structures. A critical review of the advantages and disadvantages of strengthening with SMAs is then provided, especially in comparison to conventional strengthening materials and methods. This review concludes with the identification of challenges associated with using SMAs and future opportunities that can arise owing to the proper use of SMAs.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In civil and structural engineering, building structures with robust stability and durability using sustainable materials is challenging. The current technological means and materials cannot decrease ...weight, enlarge spans, or construct slender structures, thus inspiring the exploration for valuable composite materials. Fiber reinforced polymer (FRP) features high-strength and lightweight properties. Using FRP motivates civil engineers to strengthen existing RC structures and repair any deterioration. With FRP, a system that can resist natural disasters, such as earthquakes, strong storms, and floods, can be developed. However, deterioration of structures has become a critical issue in modern construction industries worldwide. This paper reviews the FRP design, matrix, material properties, applications, and serviceability performance. This literature review also aims to provide a comprehensive insight into the integrated applications of FRP composite materials for improving the techniques of rehabilitation, comprising the applications toward the repair, strengthening, and retrofit of concrete structures in the construction industry today.
•FRP has a distinctive tensile strength property of being greater than that of steel, yet, it weighs only one quarter as much.•FRP composites were accepted as a mainstream construction material for repair, strengthening and retrofit of concrete structures.•Rehabilitation function is mainly influenced by the direction of polymers fibers used.•FRP composite is highly resistant to chloride ion and chemical attack compared to steel bars.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
PDF
