KAJIAN PENENTUAN NILAI CBR TANAH MENGGUNAKAN DYNAMIC CONE PENETROMETER PADA PEMBANGUNAN RUAS JALAN MAMBRUK-KADAMBER KABUPATEN FAKFAK

In the road planning, one of the parameters needed is the value of California Bearing Ratio (CBR). the value of CBR is used as a parameter to determine the condition of the subgrade. The study was conducted to determine the CBR value and the percentage of the subgrade bearing capacity criteria on the MambrukKadamber road, Fakfak Regency, West Papua. The method used in this study is a field survey using a Dynamic Cone Penetrometer (DCP) on a 1,9 km long track and divided every 50 meters so that the number of test points is 40 points, then the test data are analyzed using the PUPR and Kleyn methods. From the results of the analysis, the largest CBR value is 31,43% and the smallest 4,66% if analyzed using the PUPR method and when using the Kleyn method the largest CBR value is 22,23% and the smallest 3,51% with the avarege difference between both method is 3,27%. It is also known that as many as 10% of points still have poor soil bearing capacity criteri

Pengaruh Komunikasi Guru-siswa terhadap Kemampuan Berpikir Kritis Pelajaran Ekonomi Siswa SMA Taman Mulia

: This study aims to determine how the effect of teacher-student communication on critical thinking on economic subjects high school students Taman Mulia Kubu Raya. Forms of research in this study is the relationship with the clause of associative research methods / relationship. The sample was 70 students. The results of this study concluded that (1) the teacher-student communication that takes place in the teaching and learning activities in Taman Mulia High School is a Kubu Raya high (good) which in terms of the communication model by 68.28%, the elements in communications at 62.57 % and amounted to 71.14% effective communication. (2) students\u27 critical thinking skills on economic subjects Kubu Raya Taman Mulia High School as a whole amounted to 57.17% with enough categories. (3) there is a positive influence in teacher-student communication on critical thinking on economic subjects high school students Kubu Raya Taman Mulia in the amount of 8.2% while the rest is influenced by other factors

Application of Foamed Concrete and Cold-Formed Steel Decking as Lightweight Composite Slabs: Experimental Study On Structural Behaviour

Foamed concrete composite slabs (FCCS) are currently enjoying great popularity in the construction industry. Unlike conventional composite slabs, FCCS has an advantage in solving the selfweight penalty. With the advanced research in concrete technology, foamed concrete with sufficient strength properties  to meet the requirements of standard code of practise has been successfully introduced. Foamed concrete is known for its lightweight and versatility. This paper presents an experimental study on ultimate load, maximum deflection and failure mode of FCCS. Of interest are the effects of dry density and slab thickness. The slab specimens with a span of 1800 mm, a width of 840 mm and different thicknesses from 100 mm to 150 mm were prepared for the three-point bending test. The dry density of foamed concrete is 1400 kg/m3, 1600 kg/m3, and 1800 kg/m3, which has a compressive strength of about 20 MPa to 40 MPa. Dry density and slab thickness have been observed to have significant effects on ultimate load and maximum deflection. Higher dry density of foamed concrete provides better slip resistance and thus reduces shear bond failure. On the other hand, slab specimens with a higher slab thickness tend to have better bearing capacity due to greater bending stiffness. The main failure mode is dominated by localised bending on the profiled steel deck, slip-displacement and fracture of the foamed concrete

Application of Foamed Concrete and Cold-Formed Steel Decking as Lightweight Composite Slabs: Experimental Study On Structural Behaviour

Foamed concrete composite slabs (FCCS) are currently enjoying great popularity in the construction industry. Unlike conventional composite slabs, FCCS has an advantage in solving the selfweight penalty. With the advanced research in concrete technology, foamed concrete with sufficient strength properties  to meet the requirements of standard code of practise has been successfully introduced. Foamed concrete is known for its lightweight and versatility. This paper presents an experimental study on ultimate load, maximum deflection and failure mode of FCCS. Of interest are the effects of dry density and slab thickness. The slab specimens with a span of 1800 mm, a width of 840 mm and different thicknesses from 100 mm to 150 mm were prepared for the three-point bending test. The dry density of foamed concrete is 1400 kg/m3, 1600 kg/m3, and 1800 kg/m3, which has a compressive strength of about 20 MPa to 40 MPa. Dry density and slab thickness have been observed to have significant effects on ultimate load and maximum deflection. Higher dry density of foamed concrete provides better slip resistance and thus reduces shear bond failure. On the other hand, slab specimens with a higher slab thickness tend to have better bearing capacity due to greater bending stiffness. The main failure mode is dominated by localised bending on the profiled steel deck, slip-displacement and fracture of the foamed concrete

Natural Frequency of Lightweight Composite Slabs Based On Experimental Study and Numerical Modelling

Recently, lightweight composite slabs have become increasingly popular. Lightweight composite slabs are an innovation that provides a better and more convenient construction method for floor systems. Under dynamic loads, lightweight composite slabs may experience meagre inertia forces due to poor stiffness or low mass. Compared to conventional composite slabs, lightweight composite slabs are 40% lighter and more susceptible to structural resonance. Therefore, the vibration behaviour must be controlled to avoid discomfort issues. This study investigates the natural frequency of lightweight composite slabs through experimental study and numerical modelling. In the experimental study, lightweight composite slabs were prepared for the hammer-impact test. The slab thickness ranges from 100 mm to 200 mm. In numerical modelling, lightweight composite slabs were modelled in SAP2000 using a unique technique called the simplified equivalent plate model. The effective material properties were derived from the rule of mixtures and depend exclusively on elastic properties with strength characteristics. The results of the experimental study and numerical modelling agree positively. The natural frequency decreased with slab thickness, signifying that the natural frequency is dominated by mass rather than stiffness. Overall, the natural frequency of lightweight composite slabs is around 27.23Hz to 31.45Hz

Natural Frequency of Lightweight Composite Slabs Based On Experimental Study and Numerical Modelling

Recently, lightweight composite slabs have become increasingly popular. Lightweight composite slabs are an innovation that provides a better and more convenient construction method for floor systems. Under dynamic loads, lightweight composite slabs may experience meagre inertia forces due to poor stiffness or low mass. Compared to conventional composite slabs, lightweight composite slabs are 40% lighter and more susceptible to structural resonance. Therefore, the vibration behaviour must be controlled to avoid discomfort issues. This study investigates the natural frequency of lightweight composite slabs through experimental study and numerical modelling. In the experimental study, lightweight composite slabs were prepared for the hammer-impact test. The slab thickness ranges from 100 mm to 200 mm. In numerical modelling, lightweight composite slabs were modelled in SAP2000 using a unique technique called the simplified equivalent plate model. The effective material properties were derived from the rule of mixtures and depend exclusively on elastic properties with strength characteristics. The results of the experimental study and numerical modelling agree positively. The natural frequency decreased with slab thickness, signifying that the natural frequency is dominated by mass rather than stiffness. Overall, the natural frequency of lightweight composite slabs is around 27.23Hz to 31.45Hz

Neuromechanical response of the upper body to unexpected perturbations during gait initiation in young and older adults

Background: Control of upper body motion deteriorates with ageing leading to impaired ability to preserve balance during gait, but little is known on the contribution of the upper body to preserve balance in response to unexpected perturbations during locomotor transitions, such as gait initiation. Aim: To investigate differences between young and older adults in the ability to modify the trunk kinematics and muscle activity following unexpected waist lateral perturbations during gait initiation. Methods: Ten young (25 ± 2 years) and ten older adults (73 ± 5 years) initiated locomotion from stance while a lateral pull was randomly applied to the pelvis. Two force plates were used to define the feet centre-of-pressure displacement. Angular displacement of the trunk in the frontal plane was obtained through motion analysis. Surface electromyography of cervical and thoracic erector spinae muscles was recorded bilaterally. Results: A lower trunk lateral bending towards the stance leg side in the preparatory phase of gait initiation was observed in older participants following perturbation. Right thoracic muscle activity was increased in response to the perturbation during the initial phase of gait initiation in young (+ 68%) but not in older participants (+ 7%). Conclusions: The age-related reduction in trunk movement could indicate a more rigid behaviour of the upper body employed by older compared to young individuals in response to unexpected perturbations preceding the initiation of stepping. Older adults’ delayed activation of thoracic muscles could suggest impaired reactive mechanisms that may potentially lead to a fall in the early stages of the gait initiation

Fracture Energy of Foamed Concrete: Numerical Modelling Using the Combined Finite-Discrete Element Method

Foamed concrete is known as lightweight concrete that proven in the low range of densities with good strength. Numerous studies were conducted to investigate its performance in term of mechanical properties. However, these investigations are still not adequate in the requirement of failure and damage mechanisms. This is due to the lack of knowledge on fracture energy that governs the crack resistance of foamed concrete. Therefore, this paper presents the numerical prediction of fracture energy of foamed concrete using the combined finite-discrete element method. The notched beam was modelled in the two-dimensional with unstructured mesh elements and a simple material model of Rotating Crack. The results of numerical prediction signify that various notch depths have an apparent impact toward fracture energy of foamed concrete