Advances in Civil and Architectural Engineering

A novel approach for improving seismic characteristics of coupled primary-secondary structural systems

2024-08-28T14:08:14+02:00

This study evaluates the primary-secondary structure interaction in three-dimensional single- and multi-story steel frame structures. A novel and practical approach was proposed to consider the effect of secondary systems. Additionally, a technique was developed to lower the time period of coupled structures. This is particularly helpful in high-rise buildings when exposed to earthquakes. Five types of steel frames were designed, fabricated, and subjected to seismic loading. The experimental models were exposed to ground motion excitations and the finite element models were subjected to nonlinear dynamic time-history analyses. An excellent agreement between the two approaches were observed. According to the results, infill wall displacements and accelerations were considerably reduced by utilizing the deformable wall setting. In this regard, the story displacements and accelerations decreased from 209 to 211 mm and 17,8 to 18,0 meter per square second when secondary systems were used. In addition, free vibrations of the frames were considerably reduced when the concentrated mass secondary systems were implemented.

New energy-efficient composite wall from expanded polystyrene concrete in fixed formwork

2024-08-28T12:34:53+02:00

This study focused on the development and verification of the effectiveness of a new energy-efficient composite wall made of polystyrene foam concrete in a fixed formwork, prepared using light steel thin-walled structures and polystyrene foam concrete as an aggregate. This research included the development of the new patented solution, a multi-criteria analysis of this solution through comparison with the most common solutions, and experimental investigations of the heat transfer resistance of the new wall. Based on the results of a multi-criteria analysis involving eight criteria, it was established that the new solution of a composite wall in a fixed formwork is more effective than 13 traditional alternatives. Experimental studies on the heat transfer resistance, conducted at the laboratory of the Scientific Research Institute of Building Structures in Kyiv, demonstrated the heat-insulating properties of the new wall. The installation of the new wall at an actual construction site confirmed the reduction in labour and material consumption owing to the new technology. Thus, for the first time, the experimental results of the heat transfer resistance of the new wall at two cross sections (maximum thickness of polystyrene foam concrete and maximum accumulation of steel elements) made it possible to substantiate the need for external insulation of the wall. Low values of the specific labour intensity, material intensity, as well as the possibility of installing wall elements with minimal use of construction equipment make it possible to use the developed solution for a wide range of construction structures.

Effect of fibres on the interfacial shear strength of geopolymer concrete activated with water glass

2024-08-28T12:21:39+02:00

Cement, an important component of concrete, is used in construction. Unfortunately, the production of cement, releases considerable amounts of CO2 into the atmosphere. CO2 is the primary greenhouse gas responsible for global warming and finding alternatives to cement is essential to reduce CO2 emissions. Geopolymers are promising alternative binders that can completely replace ordinary Portland cement. Building large-scale structures with mass concrete leads to the formation of interfaces and joints, creating potential weak points that are prone to cracking. These connections may link concrete of different strengths or interface with different construction materials, such as steel. Ensuring cohesive performance in composite concrete structures requires a robust bond at these interfaces, which is usually achieved using shear ties. However, an excess of such ties can compromise the efficiency of the construction. To address these challenges in terms of design effectiveness and structural stability, this paper focuses on evaluating the interfacial shear strength of geopolymer concrete with and without the addition of polypropylene, steel and glass fibres. It was found that w the strength increased with the addition of fibres up to the threshold limit value and decreased thereafter. The test results show that the shear strength of steel fibre reinforced geopolymer concrete (GPC) the shear strength increment is maximum 72 %, increases by a maximum of 72 %, compared to 19 % for glass fibres.

Flexural behaviour of pre-damaged RC beams retrofitted using CFRP laminates

2024-08-21T11:14:23+02:00

This study entailed an investigation on retrofitting methods, aimed at enhancing the strength of reinforced concrete (RC) beams by applying carbon fibre-reinforced polymer (CFRP) laminates and CFRP fabrics in the flexural and shear zones of damaged RC beams. The experimental examination involved the casting and subsequent strengthening of six rectangular RC beams, via external bonding techniques utilizing both CFRP laminates and fabrics. The research design included five distinct systems of strengthening of pre-damaged RC beams up to the ultimate load level and 90 % of the ultimate load level. All RC beams were cast using M20-grade concrete and uniform reinforcement detailing. The results revealed a significant enhancement in the load-bearing capacity of the RC beams externally strengthened u CFRP laminates. Particularly, the beams retrofitted with U-shaped wrapping exhibited a substantial improvement in both crack and ultimate loads. These findings underscore the efficacy of the CFRP retrofitting approach, demonstrating a positive impact on the overall structural performance of pre-damaged RC beams. This study indicates that incorporating CFRP laminates and fabrics in the shear and flexural zones of pre-damaged beams up to the ultimate load level can enhance the ultimate load-carrying capacity by up to 13 %. The proposed approach offers a cost-effective strategy to enhance strength and maintain ductility without compromising the overall structural integrity.

Barriers and Overcoming Strategies for Lean Construction Implementation in Ethiopia: An Integrated Fuzzy AHP and Fuzzy TOPSIS Framework

2024-05-16T08:38:01+02:00

Lean construction (LC) is a valuable concept for waste reduction and project performance improvement. There is awareness of LC principles and tools among professionals and limited use in Ethiopian projects. However, adoption and implementation are still low. This study aims to identify and prioritize barriers and strategies for overcoming them to successfully implement LC in the industry. This study uses a multi-criteria decision-making (MCDM) approach by integrating the fuzzy analytical hierarchy process (AHP) and the fuzzy technique for order of preference by similarity to the ideal solution (TOPSIS). A review of the published articles along with expert guidance identified 28 barriers grouped into six categories. Furthermore, nine alternative strategies were proposed to address these barriers. The fuzzy AHP is used to determine the weights of the barriers as criteria, and the fuzzy TOPSIS method is used to obtain the final ranking of the overcoming strategies for LC implementation (LCI). The top four barriers hindering the smooth implementation of LC were "resistance to change", "lack of knowledge in lean", "lack of long-term philosophy", and "lack of government support". The most effective overcoming strategies were leadership and management, cultural change for continuous learning and improvement, and education and training. The study's sensitivity analysis robustness test confirmed the robustness and usefulness of the findings, which provides strategic insight for decision-makers and guides professionals to plan effective LC adoption.

Cement concrete containing polyethylene terephthalate and steel slag powder for pavement application

2024-11-11T11:39:41+01:00

The solid waste produced by industrial and technological advancements in the environment and construction is increasing. A large amount of industrial waste is not properly disposed of in Nigeria, which causes inconvenience to the environment and society. Utilising such waste for sustainable construction is one of the easiest and least expensive methods of eliminating and protecting the environment. This study investigated the properties of concrete pavement incorporating steel slag powder (SSp) and PET powder (PETp). The cement was partially replaced with SSp and PETp at varying proportions, and the mechanical properties (compressive strength, flexural strength, and split tensile strength) and durability properties (resistance to acid attack and water absorption) were evaluated for the concrete pavement. The results obtained indicate that the addition of SSp improved the strength characteristics of the concrete pavement, whereas the incorporation of PETp enhanced the durability performance. The findings suggest that the use of SSp and PETp in concrete pavements is a promising approach to achieving both mechanical strength and durability requirements because PETp replaces the water lost and prevents cracks from forming in concrete samples. Furthermore, to achieve best performance of the concrete pavement, the study recommends 10 % SSp and 15 % PETp as the ideal combination.