Advances in Civil and Architectural Engineering

Cotton knitted fabric waste as reinforcement in cement screed

Sandra Juradin; Bruno Bartulović, Dujmo Žižić, Silvija Mrakovčić — Mon, 19 Feb 2024 00:00:00 +0100

Cement screed consists of cement, sharp sand and water, laid as a thin layer over the concrete subfloor. Although the screed is strong, it can be additionally reinforced with fibres, most often polypropylene fibres. In this study, cotton knitted fabric waste (CKFW) was obtained from a local factory producing underwear to reinforce the cement screed. A total of eight mixtures were made: reference mixture, screed reinforced with polypropylene fibres and six mixtures reinforced with CKFW. CKFW was added in 1,25 %, 2,50 % and 5,00 % of the total volume. Before adding to the mixtures, the first CKFW group was saturated with tap water, whereas, the second CKFW group was saturated with dispersion that improves adhesion. The density and air content of the fresh mixtures were tested, and the compressive strength and flexural strength were determined when the specimens were 28 days old. The specific fracture energy is determined based on the curve from the plot of load vs. displacement. The CKFW increases the ductility of cement screeds, although it has no significant effect on the compressive and flexural strength of the specimens. The CKFW that was saturated with tap water achieved better results.

Fundamental period equations for plan irregular moment-resisting frame buildings

Jahanvi Suthar; Sharadkumar Purohit — Wed, 28 Feb 2024 00:00:00 +0100

The fundamental natural period of oscillation is a critical parameter in evaluating the design base shear of buildings. Worldwide seismic design codes typically employ height-based empirical formulas to estimate this period for various building categories, without distinguishing between regular and irregular buildings. This study proposes a formula specifically for reinforced concrete (RC) moment-resisting frame (MRF) buildings with dominant re-entrant corner type plan irregularity. A total of 190 re-entrant corner dominant building models with different shapes (C-, L-, T-, and PLUS-type), heights, and floor configurations were prepared, and eigenvalue analysis (EVA) was conducted. The fundamental natural period of oscillation for each model was evaluated and compared with the height-based formulas from seismic design codes and the period–height relationship proposed in existing literature. A nonlinear regression model, using a multi-variable power function, is proposed to estimate the fundamental natural period for these re-entrant corner dominant building models. This model considers the A/L ratio in both directions of the building, along with its height. Both unconstrained and constrained regression analyses were performed to derive a formula that best fits the fundamental natural period data. The study recommends that the unconstrained best-fit minus one standard deviation curve can conservatively define the fundamental natural period of oscillation for re-entrant corner dominant RC building models. The equation defining this curve has the potential to replace the existing seismic design code-based period-height formula.

Comparative probability-based seismic safety assessment of base-isolated buildings: A case study

Thu, 14 Mar 2024 00:00:00 +0100

Seismic fragility curves are used to assess the structural vulnerability probability at various damage states. In this study, the effects of different isolation systems on the seismic safety of a two-dimensional reinforced concrete moment-resisting frame are investigated. The reference structure was a hotel building in California, USA. A comparative probability-based seismic safety assessment for building components was conducted on the superstructure hypothetically fitted with various isolation systems. In this regard, two categories of isolation systems, including rubber‐ and friction‐based systems, were selected. The high damping rubber bearings and friction pendulum systems were considered. Incremental dynamic analyses were conducted for a suite of earthquake records to develop the fragility curves considering modelling, demand, and capacity uncertainties. Based on the results, it was observed that the building failure probability reduction was influenced by the seismic isolation systems rather than the fixed base (un-retrofitted) model. Furthermore, the high damping rubber bearings system was found to be more reliable than the friction pendulum system in the limit states considered. However, no significant discrepancy was observed in the performance of the building fitted with isolation systems at higher damage states.

Preliminary small-scaled thermal resistance testing of a masonry wall with enhanced electromagnetic shielding effectiveness

Ivan Vrdoljak, Hrvoje Krstić — Tue, 19 Mar 2024 00:00:00 +0100

This study presents the preliminary results of a small-scale masonry wall thermal resistance (R-value) measurement. Two small-scale masonry walls were constructed using regular and antimony tin oxide (ATO)-containing bricks. ATO has shown potential for improving the protection against electromagnetic radiation penetration. R-values of the walls were measured using a FluxDAQ device equipped with a heat flux sensor and two temperature sensors for obtaining the heat flux and inside and outside temperatures during the measurement. Furthermore, the thermal conductivity (λ) of the bricks was measured by using the Fox200 Heat Flow Meter. Both results can be used for determining a walls’ thermal transmittance (U-value), which is often used for describing the energy losses and as a measure of a wall's energy efficiency. This research sought to investigate whether there is a correlation between the results obtained by the small-scale masonry wall and Fox200 device. Ultimately, this experiment aims to verify whether the small-scale masonry wall non-standard method described herein can provide approximately similar results to the standardised method.

Role of spatial efficiency, layout planning, and sustainability in the success of shopping malls

Fri, 22 Mar 2024 00:00:00 +0100

Building multi-storey shopping malls has grown to be a very lucrative industry for investors in recent years. As a result, the success of a plaza depends on a variety of elements, including its design, security, appealing façade, and amenities. This study examined the structural systems, services, and architectural designs of a few of Lahore's prosperous plazas. Food courts and hyper malls provide essential functions that boost foot traffic and have the potential to revolutionise the way that entertainment amenities raise a mall's worth. Mixed-use multi-story spaces such as those that combine offices, apartments, and retail stores can also increase the efficiency of a mall in terms of sales and attractiveness. The assessment parameters in case studies include the gross area, circulation, parking area, toilet area, services area, and vertical transportation, with average values of 33,83 %, 22,00 %, 24,30 %,1,10 %, 3,05 %, and 4,60 %, respectively. These will assist future studies to determine the minimum threshold for success, making mall planning easier and more accurate. High-quality malls have higher occupancy because they offer better quality development, facilities, sustainable techniques, and amenities to support the overall development, along with shop sizes that suit international brands. This research defines the emerging trends and provides guidelines for the future architectural planning, structural systems, and services of shopping malls in Lahore to meet sustainable development goals and attract more shoppers.

Effect of single vanes on turbulent flow

Sara Ahmadi Adli; Akram Abbaspour, Ali Hosseinzadeh Dalir, Javad Parsa — Thu, 04 Apr 2024 00:00:00 +0200

In response to growing environmental and ecological awareness, eco-friendly in-stream structures such as vanes have been implemented in different parts of the world to enhance stream conditions. FLUENT (ANSYS) was used to perform three-dimensional large eddy simulation to investigate the effect of the vanes permeability rate on flow characteristics. To evaluate the numerical model accuracy, numerical and experimental free surface profiles compared. It is observed that simulated free surface profiles agree reasonably well with measured values. The effect of different permeability rates is obvious in the flow characteristics such as depth-averaged velocity distribution, tip velocity variations, formation of the secondary flows in the flow field, turbulent kinetic energy, and mean kinetic energy contours. On average, maximum velocity values in the flow field is 1,54 times the approach velocity. Tip velocity decreases up to 30,6 % for the 70,0 % permeable vane. Maximum turbulent kinetic energy and mean kinetic energy for the 70,0 % permeable vane decrease up to 58,0 % and 43,3 %, respectively. Generally significant velocity and flow pattern variations around the impermeable vane can be attributed to the local effect of the vane structure and channel cross sectional constriction in comparison to the permeable vanes.

Sustainable energy production and resilience towards floods by using hydro and solar photovoltaic energy

Bojan Đurin, Duangrudee Kositgittiwong, Nikola Kranjčić, Nguyen Thi Thuy Linh — Tue, 30 Apr 2024 00:00:00 +0200

Unexpected and intense floods have become more frequent recently; this is related to extreme weather events that are difficult to predict accurately. This necessitates new solutions to decrease the risk of flooding urban and rural areas. Moreover, such solutions should have negligible impact on the environment. There are several concepts, tools, and technical measures for preventing floods, one of which is the ‘monkey cheek’ concept for flood protection, used in Thailand for protection from river and sea floods. Monkeys collect food in their mouths and eat subsequently in stages. In a similar manner, excess water from floods could be collected and stored in reservoirs, sags, canals, floodplain forests, and unused space. Collected water could then be used for irrigation. In most cases, collected water must be pumped to distant or higher locations compared to the location where the water was collected. This requires electric energy for the pumps. This paper analyses a case study for the presented concept for the town of Ludbreg in Croatia, currently undergoing real-site measurements and calculations. A rescaled adjusted partial sums method is applied for the analysis. It has been shown that the energy potential of the local, small river Bednja in the observed location could be approximated using the “monkey cheek’’ concept. Within this, using the produced electricity from small hydropower plants and solar photovoltaic systems has been proven promising. The solution avoids building dams for flood protection, satisfying the environmental aspects.