This article presents the assessment of early-age cracking risk in a mass concrete footing which is cast under different construction conditions. A finite element (FE) model was developed for predicting temperature, thermal stress, and cracking potential in a concrete footing at early age. Different scenarios of concrete placement were considered to investigate the effect of construction stages on thermal cracking potential in the concrete. The analysis method in this study can help engineers optimize construction schedules to control temperature and reduce cracking risk in mass concrete structures.
Drying shrinkage is the major drawback of lightweight foamed concrete (LFC) as reported by many researchers. It is happened due to the loss of water in the capillary of concrete mixture. This problem caused the changes of dimension or volume of the concrete structure which lead to the cracking and failure thus shorten the life performance of the material. Once the water evaporated from the cement paste, it is impossible to replace it back. Thus, this paper studies the drying shrinkage behaviour of LFC with the confinement of woven fiberglass mesh at three different densities were 600kg/m3, 1100kg/m3, and 1600kg/m3. The woven fiberglass mesh implemented in this research is a synthetic textile fabric with an alkali resistance characteristic. The LFC specimens were wrapped 1-layer to 3-layer(s) of woven fiberglass mesh to enhance the drying shrinkage performance. The drying shrinkage test was measured accordance with the ASTM C157 specification and cured under air storage condition. Protein-based foaming agent (NORAITE PA-1) was used to produce the desirable density of LFC. The result shows that confinement of 160g of woven fiberglass mesh significantly improves the drying shrinkage of LFC compared to control and the enhancement also increase as the layer(s) of textile fabric is added from l-layer to 3-layer(s). Besides, the densities of LFC also play an important role to control its drying shrinkage behaviour. As proven at higher density of LFC the reduction of drying shrinkage value can be obtained.
The traditional structural design produces elements that can be improved from the point of view of the use of the material. As a way of perfecting these processes, methodologies such as BIM have emerged, which, although they fulfill their mission of creating information models through collaborative work, their form of parameterization is still limited. In this context, the generative design emerges as a way of designing by stipulating the parameters and restrictions to be met so that the code then delivers different alternative solutions. This document aims to synthesize different generative design applications in structural engineering to extend its use in civil engineering. To achieve this, a literature review, and a survey of professionals in the area were used to obtain their opinion. As a result, seven application cases were obtained, where the main use identified for generative design is the optimization of the amount of material for structural elements. Besides, most of the respondents are unaware or have little knowledge of what this process is about, although, after understanding it, they believe it can be used in their professional practice.
In this paper, we attempted to make an investigation to use E-waste as fractional substitution intended for coarse aggregate. The accumulation of electronic waste is a major concern in big metropolitan cities and certain tier 2 cities in which huge quantities of the order of several thousand tones is being dumped discharged and grows in an exponential haphazard manner. Bakelite waste is taken as E waste, which is heat resistant and also inert to chemical reactions obtained by crushing the outer casing of television sets. The grade of concrete which is adopted for the investigation is M25 designed by IS code method. Number of trial mixes were tried and the control mix was selected which had the compressive strength slightly more than the target strength. The coarse aggregate of the control mix was partially replace 5 to 20% by weight of coarse aggregate. After 3, 7 and 28 age curing of cube specimen, the compressive intensity was found. Similarly the 7 and 28 age tensile strength, young’s modulas, modulus of rupture be calculated by casting cylinders and prisms. The best possible quantity E-waste be added to retain the target mean strength was also determined. Through research it is bring into being that the volume of the e-waste accumulated can be reduced in a substantial manner by the above method in the field of construction and thereby protect the earth from the threatening environment.
This work presents the results of structural evaluations carried out from numerical models based on the finite element method (FEM) for a steel stair with 22.70 meters long, 8.37 high and 1.68 wide, belonging to Olympic Tennis Center, Rio de Janeiro/Brazil. A numerical model was elaborated and fitted to natural frequencies of real structure, which in turn were obtained from an operational modal test. The test was conduced by recording vibrations due to wind and traffic of people at six points over the structure, and from stochastic signals processing of these data considering frequency domain decomposition (FDD) procedure, the experimental natural frequencies were extracted. The calibrated numerical model was then used in the structural evaluation for static and dynamic loads, and it was observed that while the structural behavior obtained through the initial numerical model (used in the development of the project) indicated compliance with design codes criteria, calibrated model pointed out the need for structural reinforcement to meet vibrations service limit.
The present research work is carried out using the experimental study to evaluate the concrete made with Aggregates of the Quarry with Addition of Nanosilica containing micro-fine nanoparticles of amorphous silica dioxide (Si O2). Nanosilica has pozzolanic properties that, upon contact with water, reacts with hydrated cement to form more particles of C-S-H (gel), which reduces porosity by partially filling the pores to refine the structure and therefore gives us greater compressive strength. The recommendation of this study is to implement low-cost, low-rise housing construction.
The microstructure properties of the cement paste are improved with the addition of Nanosilica. Nanoparticles have high specific surface areas, and their surfaces are very active; an intense pozzolanic reaction between Nanosilica and CH, would accelerate the pozzolanic reactions between SIO2 and water molecules. Therefore, the smaller the pore volume, the higher the compressive strength and water absorption capacity of Nanosilica-modified pastes results.
The volume of the pores was reduced along with the increase of the Nanosilica dose. The cement and sand mixture without Nanosilica after 7 days of curing, shows a porous structure.
The growing interest in providing adequate Heating, Ventilation and Air Conditioning (HVAC) conditions for those public buildings in which they were not originally planned frequently leads to the need to install HVAC units of significant dimensions and weights in these buildings. Particularly in buildings located in urban centers, the unavailability of space to place those units has led to their installation in buildings' roofs.
From the case study of a remarkable brick masonry building located in the historical city center of Madrid, this article analyzes the structural aspects involved in the implementation of large-size HVAC units on the roof of existing masonry buildings, as well as the structural refurbishment typologies necessary for this purpose.
Thus, the study carried out focused, on the one hand, on the analysis of the HVAC new loads' impact on the previous masonry safety conditions, and the possible need to adopt strengthening actions to ensure an adequate future structural behavior, and, on the other hand, it focuses on the analysis of the aspects conditioning the design of the auxiliary support and fixing structure of those HVAC units.
The importance of structural design under fire conditions, together with the uncertainty in the behavior and resistance of reinforced concrete structures with fiber-reinforced polymer bars (FRP) at high temperatures, reveal the need for more research along these lines. Although there are studies evaluating the flexural and shear strength of elements exposed to fire, there are no standards nor regulations specifying the procedures thereto. This work proposes methods to calculate shear strength in FRP-reinforced concrete beams, with rectangular cross-section, based on the degradation of the properties of the materials and/or the reduced concrete cross-section, as recommended by (Diab, 2014), Eurocode 2 (EN-1992-1-2, 2004) and (Saafi, 2002). In accordance with the thermal analysis executed with the Super Tempcalc software, these procedures were applied to 13 beams of different dimensions and reinforcements, subjected to standard fire of the ISO-834 standard on three sides, thereby obtaining the shear capacity degradation curves for each case. The results show that the differences between the shear strength values were very small throughout the total fire exposure time.
Occupational segregation remains an essential challenge for women joining the workforce, especially in the construction industry, which is well known by extreme gender segregation. By addressing the challenge of segregation in construction, not only equal opportunities can be achieved for women, but also construction industry challenges can be addressed, such as the lack of skilled workers or reducing the cost of employees’ turnover. This paper explores the international literature regarding the challenges and barriers women face in the construction industry to compare with the Chilean construction industry. This study found that the Chilean construction has developed initiatives to encourage women in construction, and it is in better standing compared to other Latin American countries, but when compared with developed nations, more initiatives and programs need to be done. More importantly, the existing literature has identified the challenges and barriers faced by women in different regions of the world; however, limited information exists regarding such challenges and barriers in the Chilean context. The importance of discovering and identifying existing challenges faced by women in the Chilean context is that stakeholders from the construction industry and local authorities can develop programs and initiatives, such as attraction and retention programs, tailored to the specific socio-cultural context of the Chilean construction industry.
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