Response ff The High Frequency Long-Span Lightweight Floor Due to Human Walking: Harmonic Response Analysis

This paper is an investigation of high natural frequency long-spanlightweigtht floor subjected to dynamic  footfall loading of human activities. This study was carried out to examine the vibration response of the high natural frequency long-span lightweight floor, when harmonic response analysis was applied. Acceleration root mean square (RMS) was used as a method to determine the vibration response of the high natural frequency long-span floor model. The parametric studies of natural frequency of 7 up to 20 Hz and damping ratio of 0.5% and 2% were employed to investigate the response of the model.Increasing damping ratio of the model was found to have a significant effect on reducing acceleration RMS. However, increasing natural frequency of the high natural frequency long-span lightweight floor model demonstrated to have an insensitive influence on the acceleration RMS.

Experimental Investigation on the Effect of Specimen Size in Determining Fracture Parameters of Concrete

his paper presents the experimental results in investigating the effect of specimen size (ratio of beam width to aggregate size) on the value of stress intensity factor (KIC) and fracture energy (GF) using three-point bend (TPB). A test method recommended by RILEM was chosen to measure the KIC and the GF as fracture parameters. Three different specimen sizes of concrete beam with water/binder ratio of 0.2 and 0.30 were engaged in the experiments. Both qualitative and quantitative analyses based on the normalized stress against deflection curve, and the KIC and the GF were employed. Statistical analysis was carried out based on coefficient of variation of the measured value of fracture parameters in order to investigate the variability of corresponding results. It was found that specimen size have a relatively insensitive influence on the value of KIC, however, have a significant effect on the value of GF

Measuring the Effect of Strengthened Concrete on the Fracture Characteristics of Notched Concrete Beams Through a Three-Point Beam Test

This study explores the effect of increased concrete strength on the behavior of concrete failure. Experimental testing using a three-point bend (TPB) test proposed by RILEM was carried out to calculate the value of fracture energy (GF), stress intensity factor (KIC), and characteristic length (lch) of the concrete. The values of GF and lch, which are proportional to the fracture process zone based on the fictitious crack model, were employed to determine the effect of concrete strength on the concrete’s fracture characteristic. KIC was engaged to describe the initial crack in the concrete. Four different concrete strengths of 40, 47, 53, and 100 MPa—were manufactured to produce notched beam specimens with single-sized notches 25 mm deep. Results revealed that the values of GF and KIC increased in the stronger concretes. However, the value of lch decreased significantly as concrete strength increased

Experimental investigation of the flexural ductility of singly reinforced concrete beam using normal and high strength concrete

This paper discusses and reports based on the experimental investigation of the flexural ductility of singly reinforced normal strength and high strength concrete beams. Compressive concrete strength of 40 and 95 MPa were employed to create singly reinforced normal strength and high strength concrete beams, respectively. Fourteen samples made of normal and high strength concrete were engaged to observe the flexural ductility behaviour of beams on the basis of four point bend testing. Analysis on the basis of the flexural cracking, ultimate failure and curvature ductility were carried out to derive the comparison of singly reinforced normal strength and high strength beams. The beams using high strength concrete revealed a higher ductility ratio than that of normal strength concrete, i.e. 4.50 for high strength concrete and 2.60 for normal strength concrete

Characteristic of Concrete made of Ternary Cementitious System

Utilizing industrial waste materials containing pozolanic compounds has been widely investigated for cement replacement. Fly ash and microsilica are materials having significant pozolanic compounds and can be used to create ternary cementitious system. Slump of fresh concrete, porosity and compressive strength of hardened concrete were parametric study investigated in this study of ternary cementitious system.  Three types of concrete mixtures, i.e. concrete mixture using original Portland cement (OPC) as normal concrete, OPC-fly ash-microslica without superplasticiser, and OPC-fly ash-microslica with additional superplasticiser have been investigated. Fresh concrete using fly ash and microsilica demonstrated having higher slump and lower porosity than normal concrete. Compressive strength of concrete using fly ash and microsilica were higher than normal concrete. Utilizing fly ash and microsilica as ternary cementitious system was found to have significant effect on compressive strength and porosity of hardened concrete

Studi Tingkat Permeabilitas Beton Serat Baja Benrat

Beton serat yang memanfaatkan baja benrat yang merupakan limbah industri konstruksi maupun industri lainnya masih belum banyak termanfaatkan. Penggunaan serat baja benrat akan berdampak pada penurunan kualitas keliatan betonnya yang termasuk diantaranya adalah permeabilitas beton. Beton serat baja benrat dalam penelitian ini menggunakan bentuk bebas dengan ratio l/d dari 20, 40 dan 60 serta volume penggunaan antara 1% hingga 4% dari volume beton yang digunakan. Kualitas permeabilitas beton akan meningkat secara signifikan dengan setiap penambahan ratio l/d dan volume serat baja benratnya bahwa peningkatan nilai permeabilitas akan lebih dari 5% setiap 1% penambahan serat baja dengan panjang ratio l/d= 20, dan untuk setiap 1% penambahan serat baja dengan ratio l/d = 40 akan bertambah nilai permeabilitasnya  lebih dari 100%, sedangkan untuk setiap 1% penambahan serat baja dengan ratio l/d=60 akan bertambah nilai permeabilitasnya lebih dari 200%. Demikian juga terjadi penurunan kulatisa workabilitas dari beton segar yang dihasilka

Experimental investigation of the effects of aggregate size distribution on the fracture behaviour of high strength concrete

This paper examines the influence of different aggregate size distributions on the fracture behaviour of high strength concrete. Three-point bend test was performed on 63 notched beams casted using three aggregate size distributions and two water to binder ratios. The total fracture energy, GF, and critical stress intensity factor, KIC, were used to determine the fracture characteristic of concrete. The results show that the values of GF decrease substantially with increasing coarseness of aggregate grain structure, λ. Values of KIC also decreased but demonstrated only limited dependence on λ. In contrast, reducing the total w/b ratio substantially increases the value of KIC but had no measurable effect on GF