Based on the study of chloride migration coefficient and hydration heat evolution, it was found that the use of ternary blended cement was effective to achieve desired service life and minimum crack index. On the other hand, a high level of compressive strength is required for marine concrete mix design.
This study is a basic research for estimating compressive strength of the high strength concrete by utilizing mechanical impedance method. Here, an experiment was performed to investigate the correlation and analysis about the actual compressive strength and the index value deduced by mechanical impedance method. Later, if an additional verification is carried out, it is determined to be possible to use a mechanical impedance method in the field.
The purpose of this study is to investigate the correlation of the ultrasonic velocity and the compressive strength according to the strength zone. According to results of the experiments, in the results of including early age compressive strength, correlation of compressive strength and ultrasonic velocity was high. It is determined that Ultrasonic velocity in the high strength section is not significantly affected by moisture.
A RSM-based reliability analysis approach is applied to evaluate the safety of floating structures considering uncertainties associated with various design variables. Uncertainties in both load and resistance related variables are explicitly considered in the analysis. It is expected to be practically applied in the reliability-based design of real structures including floating structures.
A portable device which calculate and analysis the SOC structure data. This device can be used to estimate the building prior to install the sensing system. This sensing tools can help the system engineers to analyze the large SOC structure’s responses.
In general, the lateral resistant of bearing in a straight bridge is designed for lateral load such as wind or seismic forces. In this study, however, it is found that the cause of damage of bearings in a straight bridge adjacent to the curved road is the centrifugal force or the breaking force of the vehicle. Also, it is suggested that the repair method for the damaged bearings.
When processing with wood floor covering on wet ondol floor, there are frequent defects caused by floor condensation, floor loosening, lowering of adhesiveness, wood contraction and swelling. The working method is still conventional with problems of lower indoor heating efficiency. Accordingly, ordinary wood floor covering is too expensive without any special functions or features, and it is necessary to suggest reasonable solutions or methods.
This study evaluated the lateral thermal deformation induced by environmental factors for a precast I-girder. Lateral temperature gradients across the cross-section of the girder were calculated using analytical equations based on daily solar radiation, temperature variation, and wind speed. Then the lateral thermal deformation showed an average of approximately 40% to 71% of the tolerance for the initial lateral deformation of the girder, defined in the PCI bridge design standard.
In this paper, the strategy of the research project was introduced to develop the safety evaluation factors and the monitering system of underground lifelines against the ground subsidence. This study will be carried out in three steps of concept design, critical technique development and technique verification.
The collapse of a large infrastructure cause serious losses. Therefore, there has been an increasing demand in using Structural Health Monitoring techniques for the building structures so that their maintenance cost and time can be reduced. In this study, a experimental evaluation of abnormal behavior using data from a seismograph that already installed for potential of low-cost safety assessment.
According to the available date sources, 1,814 bridges failures occurred over the past 210 years in the United States. The most frequent cause of bridges failures were attributed to external events such as: floods, collisions, scour, overloading and deterioration. Among these external events, Hydraulic factor caused the maximum number of bridges failures with 54% of the total failures. 20% of hydraulic factor was failed by scour. Thus, base on the result of reviewing design basis and safety assessment practices, criteria for determining safety assessment of bridge foundation scour is proposed. 25 bridges were reviewed for applicability to scour safety assessment of passing bridges in river channels.
The purpose of this study is inspection of concrete using impact resonance method and UPV(Ultrasonic Pulse Velocity) method. The frequency polygon of non-destructive testing result shows that non-destructive testing is closely related to compressive strength of concrete.
In this study, periodical configuration survey is carried out on the subject of the suspension bridge in service. Its reliability and structural modeling validity are performed by comparison and analysis of interpretation value through the structural analysis.
In this study database on the results of in-depth inspection was built and statistical analysis was performed on the major faults for concrete dams. using condition evaluation results for existing concrete dams.
Vibration measurement analysis and In-depth inspection were carried out to understand the cause of defects occurred on joint of bridge.
A cause of defects, such as metallic sounds, water leak&corrosion and rubber seal rupture turn out to be due to deterioration and vibrating impact by period so that the bridge is in need of repair and effective maintenance.
Concrete with blast furnace slag (BFS) shows varied strength development properties different from normal concrete. Therefore, a precise prediction of compressive strength using a full maturity model is desired. The purpose of this study is to predict the compressive strength of concrete with BFS by calculating the apparent activation energy (Ea) and rate constant (kT) for each BFS replacement ratio. The method of Carino Model is used in this study for predicting compressive strength of concrete with BFS.
This paper reports the development of upgraded strain energy frame impact machine (SEFIM) with larger and faster impact capacity. The impact load capacity of SEFIM was improved by applying a 200 tonf hydraulic jack while the impact velocity was significantly increased by reducing the diameter of energy frame and by applying different materials in the energy frame. In addition, the length of transmitter bar was increased to capture pure material response by avoiding the influence of reflected stress wave in the transmitter bar. Experimental test results showed the faster strain rate (186 /sec) than that (10-40 /sec) of previous SEFIM.
The intent of this research is to apply DOE in mix proportioning of high strength self-compacting concrete (HSSCC) and to assess the effect of different process parameters on HSSCC. The effect of water-binder ratio, cement content, fine aggregate percentage, fly ash content and superplasticizer content on compressive strength, passing ability, and manufacturing cost were studied.
This research investigated the effects of adding ground granulated blast furnace slag (GGBS) on the pullout resistance of smooth steel fibers embedded in GGBS cement grouts. 40% of cement in the grouts was replaced with GGBS to enhance the flowability and durability of grouts containing steel fibers. The pullout resistance of steel fibers embedded in grouts showed continuous enhancement as the age of grouts increased. The pullout resistance of GGBS grouts was higher than that of grouts without GGBS.
The energy absorption capacity of ultra high performance fiber reinforced concretes (UHPFRCs) was investigated at high strain rates (45 – 92 s-1) using a strain energy frame impact machine. The UHPFRCs investigated in this study showed much higher energy absorption capacity, fracture energy, ranging 42 and 71 kJ/m2 at high strain rates than that (31 and 43 kJ/m2) at static rate. The energy absorption capacity of UHPFRC at high strain rates was strongly dependent on fiber type and fiber volume content.