Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Analysis and design of the structure are the most critical steps in the pre-construction steps involved. Nowadays, as technology is well developed, there is plenty of software available to carry over the analysis and design of any structures in a short period. In every software, the building model with all storey will be modelled, and loads are applied to the modelled structure on respective members, and their responses will be studied for the whole structure. But in reality, the building will be constructed in sequence as a step-by-step process, i.e., storey after storey with their respective loads, which may produce different responses. This analysis with sequential loading at each step is called Construction Sequence Analysis (CSA). In the present project work, the ten-storey setback building with a built-up area of 25m x 30m placed on the slope of 10°, assumed to be situated in Darjeeling, is modelled in ETABS software. The loads, namely gravity and lateral loads are applied to the developed model. Then the model is analyzed for different loads and their combinations as prescribed by IS codes. The combinations that produce high response are selected and dead load in those combinations are replaced with three modes: CSA without P-Delta effect, CSA with P-Delta effect, and CSA with P-Delta and Time-dependent effects combined. Thus the model is analyzed with these three additional combinations along with selected conventional load combinations. The various comparisons such as storey displacement, and storey drift between these four combinations of analysis were studied, and results were discussed. The building design is also done based on the analysis performed.

Liquefaction is a loss in soil’s resistance which can lead to disastrous and expensive consequences in terms of human lives and material damages, hence the interest of this laboratory study. The article explores the relative density influence in addition to the main parameter of the fines content on the liquefaction potential of soils. The study is based on a very large number of undrained monotonic triaxial tests undertaken on samples of reconstituted saturated sand and silt mixtures with 6 levels of initial relative density ranging from 15 to 90%. The materials used are levied from different level of deepness in the coastal region of Kharouba in the wilaya of Mostaganem. In this experiment, the sand-silt mixtures were separated to form the study samples. The aim of this work is, on one hand, to confirm and update the results of previous works (Bensoula et al., 2018) and on the other hand the study of the influence of relative density on the liquefaction potential of soils and the introduction of the concept of relative density threshold. The results of the tests confirm that the studied soil is most likely to be liquefied at a fines content between 0 and 30% depending on the equivalent intergranular voids and the equivalent relative density. These parameters are primordial for the characterization of soils sensitivity to liquefaction. In this study, the results showed that the resistance to liquefaction increases in a linear way with the relative density up to a threshold relative density value according to the fines content, which means that increasing the relative density improves the liquefaction resistance but only up to a threshold value of relative density given according to fines content.

This study investigates the effects of basic mix design variables such as water/cement ratio (w/c), slump flow, coarse-to-total aggregate ratio (CA/TA), and maximum aggregate size (Dmax) on the main characteristics of self-consolidating concrete. The w/c of the mixtures was either 0.42 or 0.50. The CA/TA ranged between 0.45 and 0.53. Slump flow was adjusted to 550, 650 or 720 ±20 mm by varying the superplasticizer content. Dmax was varied as 10, 15 and 20 mm. V-funnel, L-box, rheometer, sieve segregation tests and a new test method, recently developed by the authors, for dynamic segregation resistance were performed. The effect of each variable on the test results were effectively summarized in a table. Increasing the w/c, CA/TA and Dmax decreased the superplasticizer demand and increased the flowability. When the slump flow, w/c and CA/TA were higher, viscosity was found to be lower. Higher values of CA/TA and Dmax were found to reduce the passing ability. Increasing the slump flow (or superplasticizer content), CA/TA and Dmax disturbed the stability. Generally, the effects of w/c and slump flow on the SCC characteristics were more pronounced when compared to those of CA/TA and Dmax. Good correlations were obtained between several test results.

Bitumen is modified with various modifiers to diminish the deformation occurred in flexible pavements due to traffic loads and the effects of climate. Polymer modification and more specifically Styrene-Butadiene-Styrene (SBS) copolymer modification is one of the most common methods to enhance the physical properties of bitumen. However, the polymer modified bitumens could exhibit different rheological properties compared to original bitumen. In this work, it is aimed to investigate the effects of SBS copolymer on thermorheological properties of bitumen by means of state of art test methods. To this end, a rheological program including small amplitude oscillation shear test (SAOS), construction of master curves by using time-temperature superposition (TTS) principle, determination of zero shear viscosity (ZSV) and multiple shear creep recovery tests (MSCR) were employed along with other fundamental tests. SAOS test result signifies a positive effect of SBS on the viscoelastic deformation nature of bitumen. The master curves of the complex viscosity of binders reveal that SBS modifier reduced the Newtonian flow properties of bitumen. The decrements in non-recoverable creep compliance and the increment in percent recovery signify that SBS modifier has dramatically enhanced the applicability of bitumen as a binder in flexible pavement at mid to high-temperature ranges.

The proper management of demolition construction waste from the construction industry is an issue that has gained relevance over the last years in several research centers around the world and, in this context, researches on the potential of using construction and demolition waste to execute pavement layers have been stood out. The paper presented results of a research performed to evaluate the characteristics of the material produced by a waste treatment/beneficiation industrial plant. Tests to verify the suitability of the material as pavement subbase material were performed according Brazilian code - grain-size distribution composition, maximum characteristic dimension, shape particle index (SPI), contaminant percentage and sieving process. The results obtained indicated that the recycled aggregates investigated performed well in all the requirements of the reference standards used and only one correction, related to grain size distribution, was performed using a sieving process. It is important to highlight that the tests and analyses must be performed constantly when forming each aggregate batch, since the recycled aggregates are usually quite heterogeneous, with characteristics that may vary depending on the type of work, construction materials used or period of the year.

In critical earthquake-prone regions, many kinds of old-dated industrial facilities having structural deficiencies exist. Evaluation of seismic performance of these buildings to reach a sufficient level is quite vital. This paper scopes seismic performance assessment of an existing industrial structure. In the study, a comprehensive methodology is presented to carry out the seismic evaluation process of the buildings. The entire process is illustrated using a case study from an existing industrial precast facility. In this scope, initially, construction system, geometry, layout and material properties of the examined structure were determined through lab studies and site surveys to assess the performance level. Secondly, the current status of the structure was modeled using Midas Gen finite element software and a series of analyses were performed to reveal the seismic performance. In the analyses of seismic performance, the non-linear pushover analyses method was employed in seismic code. In the model the fiber and lumped hinges were assigned to the columns and beams, respectively. The strains occurring in the column cross-sections were calculated using the curvature values obtained from the corresponding members assigned hinges. These values were compared with the limit values which were specified in the code. It is concluded that this case study presents a practical approach for engineering applications regarding the seismic evaluation of industrial structures from the perspective of update codes.

The purpose of this study was to evaluate the performance of gravel impact compaction piers system (GICPs) in improving a 3.5m thick loose silty sand in a multilayer coastal soil system located in Bushehr, Iran. The liquefiable sandy soil layer was layered on clay layers with moderate to very stiff consistency and below the engineering embankment layer with a thickness of 1.8 m. Implementation of gravel impact compaction piers is a new generation of aggregate piers. Gravel impact compaction piers were used to improve the liquefiable soil layers and to increase the bearing capacity and reduce subgrade settlement to withstand surface infrastructures. The process of making gravel impact compaction piers in a triangular or square-patterned grid was created using three types of special mandrels and feeding and compacting the gravels in the cavity in several stages without removing the soil from the cavities. The experience gained in this case study showed that artificial liquefiable was created immediately after the construction of these piers in a limited area and the soil became unstable. After about 11-14 days, the soil stabilized rapidly. The results of the standard penetration test in the matrix soil around the piers showed that the amount of (N1)60 in compacted soils was in the range of 21-30 and on average 15 times the amount of (1-3) in the initial soil. Also, the relative density of the initial soil was increased from 25% to 75% after soil improvement. Accordingly, by relying merely on the compaction properties of the piers and without relying on other primary soil remediation factors, such as piers drainage and soil texture change, the safety factor of the improved soil is 1.7-1.95 times the minimum required according to the two risk levels in the design.

Concrete decomposing the organic compounds on because of natural or anthropogenic contaminating sources with photocatalysis existing in its structure is called self-cleaning concrete. In this study, the self-cleaning concrete with industrial waste has been searched from the point of mechanical and physical characteristics. Fly ash, blast furnace slag and sepiolite materials has been used as industrial waste in concrete. Titanium dioxide (TiO2) has been used as photocatalysis material. Specimens with the dimensions 15×15×15 cm were produced using 0 %, 10 %, 20 % and 30 % industrial wastes and 0 %, 1 %, 3 %, 5 % TiO2 by weight instead of cement. Compressive strength, unit weight, and ultrasonic pulse velocity tests were performed on the specimens after 28 days standard cure. Rhodamine-B test in Italian UNI 11259 standard and additional Phenantroquinone test have been performed as self-cleaning test. XRF test also has been made on some of the samples for the chemical analysis. The best photocatalysis performance has showed in the concrete including 5 % TiO2. Test results show that 10 % use of industrial wastes in self-cleaning concrete production is recommended from the point of economic and environmental benefits.

The reverberation time was tested in a reverberation chamber with three acoustic absorbent materials commonly used in construction. The tests were performed with different materials, setups, and back air layers. Results have been compared with those where this material is placed as a single piece. Analyzing obtained data, a linear regression model is established to predict, for certain frequencies, the alteration produced in the reverberation time. So, knowing the absorption coefficient of an amount of material, it is possible to predict the different absorption coefficients placing the same material in separated pieces and different distances from room walls. The model has been validated and tested, which demonstrates its accuracy, it has also been proved to be applicable to a wide variety of materials. It becomes a simple predictive tool that allows to estimate in situ the alteration in the reverberation time due to the separation of the absorbent material in patches.

This paper studies 123 hydraulic bridge failures in China from 1998 to 2018. The geographic distribution, age distribution, bridge type distribution, time distribution and the hydraulic bridge failure causes are analyzed. Six typical failure cases of hydraulic bridges are analyzed in detail. 100 hydraulic bridge failures occurred in southern China so hydraulic bridge failures are much more common in this area. The average service life of these bridges is 28.9 years. The beam bridge accounts for the largest proportion of hydraulic bridge failure because 71 (57.7%) beam bridges were destroyed by flood. Hydraulic bridge failure mainly occurred between 2009 and 2014, which was related to the impact of the Wenchuan earthquake. The incidents major causes include unexpected flood, earthquake, old bridge, over sand exploitation, low awareness of hydraulic bridge damage, extreme morphology of the river, etc. There are both natural factors and man-made factors. These results show that three aspects should be paid attention to: (1) unexpected flood; (2) appropriate bridge type; and (3) extreme morphology of the river.