Computational and experimental simulation to analyze loss in concrete cover by reinforcement deformation in solid slabs

ABSTRACT Adequate cover thickness contributes to the correct performance of reinforced concrete structures. Spacers are recommended in standards to maintain a concrete cover; however, many regulations do not provide sufficient guidelines for their use, resulting in poor construction. A research program was developed for solid slabs through computational and experimental simulations to minimize errors in the cover by assessing different reinforcement bar diameters and spacer distribution, considering realistic element construction and standards, combining theory with practice. The results show that the use of spacers does not guarantee the design cover for some reinforcement bar diameters, as 4.2 and 5.0 mm, and regardless of the spacer distribution configuration assessed, these meshes undergo permanent deformation, thereby damaging the cover and consequently impact structural performance. Meshes of 6.3 and 8.0 mm diameters present deformation within the cover tolerance. Therefore, it is preferable to choose bigger diameters and larger mesh spacing to guarantee the projected cover, contributing to the correct performance of the structures, solving one of the major problems in this type of construction.

Seismic Performance Degeneration of Assembled Concrete Columns with Grouting Defects

In order to evaluate the influence of internal defects of semi-grouting sleeve connection on seismic performance of assembled monolithic columns, four specimens of assembled monolithic concrete column with semi grouting sleeve connecting reinforcement bar were fabricated with 10%, 20%, 30% internal defects. The test results show that (1) the assembled columns are all damaged by bending, the grouting layer of the assembled column can be pulled apart easily and the cracks develop more closely on the upper part of the sleeve; (2) the larger the internal defects in the sleeve, the less the cracks on the column, and the less sufficient the cracks development; (3) the seismic energy dissipation capacity of the column without defect is better than that of the defective columns.

Comparative Evaluation of Crack Width for Reinforced Concrete Bridge Deck

Cracking in reinforced concrete bridge decks is a massively concern in the India. Many concrete bridge decks, inobservant to the age of construction, have shown different levels and patterns of cracking. Not only does cracking of bridge decks weaken the bridge infrastructure, but also allows the inflow of corrosive agents into the reinforcement. In this study, the crack width evaluation of RC bridge deck of span of 5 m. and 9 m. is based on equations given by IRS Concrete Bridge Code 1997 for different cases like- the effect of depth variation, reinforcement diameter, clear cover, variation in live load moment, spacing of tension reinforcement and different no. of tension reinforcement bar to constant width for the same crosssection. This study concluded that crack width increases with increase in clear cover, variation in live load moment and spacing of tension reinforcement while it decreases with increase in reinforcement diameter, depth of the bridge deck and number of reinforced bars and percentage change evaluation of different parameter of 5m and 9m span bridge deck. Keyword: Crack Width, Cracking, Bridge Deck Slab, Crack Spacing.

STUDY ON BONDING PROPERTY OF POLYURETHANE CEMENT (PUC) TO STEEL BAR

The pull-out test of the bar and PUC is carried out in this paper, the effects of protective layer thickness, reinforcement anchorage length, diameter and shape of reinforcement on bonding properties were studied. The results show that the bond strength between reinforcement and PUC material increases with the increase of the thickness of the protective layer, but decreases with the increase of the anchorage length and diameter of reinforcement. The bond strength of bare round steel is significantly lower than that of ribbed steel, and the maximum bond strength is about 47.4% of ribbed steel. By analyzing the bond slip curve obtained from the pull-out test, the stress process of bond anchorage between reinforcement bar and PUC material is mainly summarized into three stages: the rising stage, the falling stage and the residual stage. The characteristics of the curve, the stress process and the failure mode of specimen at each stage are analyzed.

Deformational behavior and damage mechanism of R-UHPFRC beam subjected to fatigue loading

The fatigue behavior of a reinforced UHPFRC (Ultra High Performance Fiber Reinforced Cementitious composite) T-shaped beam under four-point bending is investigated. The beam was subjected to a fatigue loading range equal to 49% of the static resistance and failed after 0.88 million cycles. It was instrumented with extensometers, strain gauges and distributed fiber optic sensors for strain monitoring. The fatigue process consists of three stages: with rapid, stable and again rapid growth of strains during 10%, 80% and 10% of total number of fatigue cycles, respectively. Except of the first 10%, this process takes place locally; therefore, it cannot be followed with the deflection measurement. During the stable stage, growth of strain occurs at minimum loading level in the fatigue cycle, indicating a fatigue damage process under tensile-compressive response of UHPFRC. Advanced fatigue crack propagation in the reinforcement bar determines the location of rupture of the beam. When the remaining cross-section of the rebar does not suffice to carry the tensile load, stress is transmitted to the encompassing UHPFRC causing its fast deterioration. Complete rupture of the rebar occurs only at the end of the test, when the beam collapses.

PERBANDINGAN PERHITUNGAN VOLUME PEKERJAAN DAK BETON BERTULANG ANTARA METODE BIM DENGAN KONVENSIONAL

With the development of technologies, some engineers still have a limit about technologies that can help them on their project. One of the technologies in the construction field is Building Information Modelling (BIM). BIM is an innovation from Information Communication Technology (ICT) in the construction world. Applications from BIM used in this research are Cubicost Take-off Architecture & Structure (TAS) for concrete working volume calculation and Cubicost Take-off Reinforcement Bar (TRB) for reinforcement working volume calculation. In this research, the writer aims to compare the calculation of roof plate working volume between the Building Information Modeling method with the conventional method. On concrete working volume calculation with Cubicost TAS, the calculation has the same number as conventional calculation or having 0% differential. The working volume calculation between Cubicost TRB and conventional calculation has an accurate result with a differential of 0.59% on reinforcement. The calculation process with Cubicost, which has an automatic system, is shorter and not taking much time than the conventional one, which has a step-by-step process and formula that the writer should be studied first. ABSTRAKSeiring berkembangnya teknologi, masih terdapat engineer yang dapat dikatakan terbatas dalam pengetahuan teknologi yang dapat membantu pengerjaan proyek mereka. Salah satu teknologi yang ada pada bidang konstruksi merupakan penggunaan Building Information Modeling (BIM). BIM merupakan salah satu inovasi yang termasuk dalam bidang Information Communication Technology (ICT) yang berada pada dunia konstruksi. Aplikasi BIM yang digunakan pada penelitian ini adalah Cubicost Take-off Architecture & Structure (TAS) untuk perhitungan volume kebutuhan beton dan Cubicost Take-off Reinforcement Bar (TRB) untuk perhitungan volume kebutuhan besi. Penelitian ini bertujuan untuk membandingkan perhitungan volume pekerjaan dak beton bertulang antara metode Building Information Modeling dengan konvensional untuk mengetahui manfaat dari penggunaan BIM pada perhitungan volume pekerjaan dak beton bertulang. Pada perhitungan kebutuhan volume beton dengan aplikasi Cubicost TAS, perhitungannya menghasilkan angka yang sama dengan perhitungan konvensional atau perbedaan 0%. Pada perhitungan kebutuhan berat besi untuk pekerjaan pembesian antara aplikasi Cubicost TRB dengan perhitungan konvensional menghasilkan hasil yang akurat dengan perbedaan 0.59%. Proses perhitungan dengan Cubicost yang memiliki sistem otomasi dapat dikatakan lebih singkat dan tidak memakan waktu jika dibandingkan dengan konvensional yang membutuhkan cara pengerjaan satu per satu dan rumus yang perlu dipahami terlebih dahulu.

Distributed fiber optic monitoring of a CFA pile with a central reinforcement bar bundle

In this paper, we present an application of distributed fiber optic sensor (DFOS) technology to measure the strain of a continuous flight auger (CFA) test pile with a central reinforcement bar bundle, during a static load test carried out in London. Being distributed in nature, DFOS gives much more information about the pile performance as compared to traditional point sensors, such as identifying cross-sectional irregularities or other anomalies. The strain profiles recorded along the depth of the piles from the DFOS were used to calculate pile deformation (contraction), shaft friction, and tip resistance under various loads. Based on this pile load test, a finite element (FE) analysis was performed using a one-dimensional nonlinear load-transfer model. Calibrated by the shaft friction and tip resistance derived from the monitored data, the FE model was able to simulate the pile and soil performance during the load testing with good accuracy. The effect of the reinforcement cage and central reinforcement bar bundle were investigated, and it was found that the addition of a reinforcement cage would reduce the pile settlement by up to 20%.

Punching above its weight: life cycle energy accounting and environmental assessment of vanadium microalloying in reinforcement bar steel

High-strength-low-alloy reinforcement bar steels prepared by vanadium microalloying methods have the potential to dramatically reduce the embodied energy and carbon footprint of buildings.