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Civil Engineering Forum Teknik Sipil
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Articles 8 Documents
Search results for , issue "Vol 17, No 2 (2007): MEI 2007" : 8 Documents clear
KAJIAN POLA-HEMAT PEMBERIAN AIR IRIGASI Nurrochmad, Fatchan
Civil Engineering Forum Teknik Sipil Vol 17, No 2 (2007): MEI 2007
Publisher : Civil Engineering Forum Teknik Sipil

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Abstract

Paddy is a semiaqutic crop that is also adaptic to water lacking condition such as paddy gogo. As common practice in Indonesia, farmers use excessive amount of irrigation water for their paddy field, hoping to yield maximum amount of harvest. Such practice result in the problem of irrigation water supply due to significant amount of irrigation water requirement. However, paddy harvest is actually influenced by the crop variety, water management, soil nutrient availability and land management. A study of irrigation watering pattern is required to obtain irrigation water saving based on the paddy botanical characteristics related to soil nutrient appropriate management in order to gain optimal harvest. This study applied the pattern of irrigation water supply to five plots of 2x3 m2 model consist of 7x11 points, filled with sandy clay soil. The pattern were continuous flooding (PTM), semi flooding – moisturing – semi flooding (SPS), semi flooding - moisturing (SPP), semi flooding – semi moisturing (SPSP) and flooding - moisturing (PP). Three seeds were planted in each point of PTM and PP pattern, and one seed for each of other pattern. Nutrient were given for every paddy plot at the 8th , 25 th and 40 th day of cultivation. Result of this study showed irrigation water used, which did not include land preparation, and harvest under the PTM, SPS, SPP, SPSP and PP pattern were 5385 l and 3,9 kg, 4290 l and 3,9 kg, 4530 l and 4,3 kg , 4265 l and 3,0 kg and 3915 l and 4,9 kg respectively. PP pattern used the least amount of irrigation water but yielded the filler to yield the optimum result, based on the paddy botanical characteristic and appropriate soil nutrient management. It also saved 33,8 % irrigation water in compare to the conventional practice based on the standard stated by the Ministry of Public Works.
PEMANFAATAN KULIT ALE-ALE SEBAGAI AGREGAT KASAR DALAM PEMBUATAN BETON Suratmin, Suratmin; Satyarno, Iman; Tjokrodimuljo, Kardiyono
Civil Engineering Forum Teknik Sipil Vol 17, No 2 (2007): MEI 2007
Publisher : Civil Engineering Forum Teknik Sipil

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Abstract

At present cockle shells of ale-ale are used only as materials of heaping up muddy yards or roads in Ketapang City. Therefore, it is a challange to conduct study to utilize cockle shells of aleale as aggregate for concrete. It is expected that the result of this study can not only give additional economicall value for cockle shells of ale-ale, but also reduce impacts on environment. In the present research, intact and broken cockle shells were used as concrete aggregate mixed with white sand, and white Portland cement. The amount of cement used is 300 kg/m3. The composition of both intact and broken cockle shells of applied in the research was 100%, 75%, 25%, and 0%. The specimen of intact cockle shells ale – ale was made in various shape and size namely sylinder-shaped models of ∅150 x 300 mm and ∅80 x 160 mm and a ‘concrete brick’-shaped model, while specimen broken cockle shells of ale-ale were sylinder-shaped models of ∅150 x 300 mm and ∅80 x 160 mm, a cube-shaped model of 70 x 70 x 70 mm and a ‘paving block’- shaped model. The research aims at finding the compressive strength of 28 days old, abration of concrete, and impact resistance of concrete. From the result of the research, it can be identified that the specific gravity of concrete with intact and broken cockle shells of ale-ale with the variation of 50% corresponds to a ‘normal concrete’ category. While specific gravity the intact cockle shells with variation of 50% is 2367.82, the broken cockle shells with the variation of 50% is 2302,66. Based on the result, it can also seen that with the variation of 50%, the highest compressive strength of concrete in the mixture of intact cockle shells of ale-ale is 24.98 MPa, and for broken cockle shells of ale-ale is 27.53 MPa.
KAJIAN PENGELOLAAN AIR IRIGASI BENDUNG PIJENAN Umar, Fauzan; Legono, Djoko; Nurrochmad, Fatchan
Civil Engineering Forum Teknik Sipil Vol 17, No 2 (2007): MEI 2007
Publisher : Civil Engineering Forum Teknik Sipil

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Abstract

Bantul Regency is about 506.85 km2 consists of 16,440 ha paddy fields and 34,245 ha upland fields. The Pijenan weir is one of weirs located in Bedog river in Bantul Regency. The weir provides irrigation water for Jigutan command area (Pijenan Upstream) of 2.074 ha. Kebonongan command area was previously irrigated from Kamijoro free intake in Progo River. The Kamijoro free intake did not properly function properly due to the sediment deposited in 1969. This condition requires supply taken from Pijenan weir. Irrigation water supply taken to Kebonangan command area can be carried out if irrigation water to Jigutan command area has been optimum. Optimally utilized irrigation water for Jigutan command area is necessary based on the crop pattern and crop variety in order to maximize the farmers’ profit. Based on the restitution of irrigation management policy, farmers free to decide which crop variety will be cultivated in accordance to paddy-paddy-palawija pattern. Paddy as the main crop and palawija (corns, beans, peanuts, onion, and chilly) can be cultivated anytime in order to gain the maximum profit based on the available water in Jigutan command area. The optimization analysis of irrigation water allocation for Jigutan command area was performed using the linear program. Water allocation for Jigutan command area of 100% and 50% of available water resulted in optimum cultivation area of 822.88 ha with profit of Rp 7.688.517.507,00 and 612.88 ha with profit of Rp 6.743.877.335,00. The crop intensity with water allocation of 100% and 50% was 278% (197% paddy and 81% palawija) and 207.05% (114.05 paddy and 93% palawija), respectively. These results described that the optimum area of paddy crop cultivation is significantly sensitive to irrigation water allocation compared to the palawija market price. This explains why the profit obtained by the farmers is dependent from the palawija variety. Results of the optimization of irrigation water allocation of 100% and 50% of the available water to Jigutan command area provides annual supply to Kebonongan command area for 155.233.586 m3 and 75.316.444 m3, respectively.
REKAYASA PEMBUATAN BALOK KAYU STRUKTURAL BERUKURAN BESAR DARI BALOK-BALOK KAYU BERUKURAN KECIL DENGAN PERKUATAN BAJA TULANGAN Rochman, Abdul
Civil Engineering Forum Teknik Sipil Vol 17, No 2 (2007): MEI 2007
Publisher : Civil Engineering Forum Teknik Sipil

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Abstract

At present, it is difficult to obtain the large size of wood beams, whereas the need to support heavy constructions is high. On the other hand, significant amount of small wood beams and log are available everywhere. Usually, these small wood beams and log are used to non-structural, or even for firewood. The objective of this study is to create a technology to made large structural wood beam by using the small wood beams. This study used 17 test models with the dimensions 40 mm x 90 mm x 1900 mm with the composition, 5 test beams made of whole mahoni (full section-BU), 6 test compiled wood beams made of 2 side layers (BS2BS), and 6 test compiled wood beams of 3 side layers (BS3BS). From those compiled beams made, three of them are made without strengthening, and the other three are given double steel bar strengthening using steel bar with the diamater is 8 mm. The result of this research shows that the load capacity of compiled wood beam increase significantly, i.e. about 87 % for BS2BS and 96% for BS3BS. The stiffness also increses as well, i.e. 79,4% for BS2BS and 90,5% for BS3BS. Therefore, it can proved technically, that it is possible to make big wood beam structure for heavy construction by using smaller dimension beams which has load capacity and performance is near with the whole beam.
HIDROGRAF SATUAN: PERMASALAHAN DAN ALTERNATIVE PENYELESAIAN Sujono, Joko; Jayadi, Rachmad
Civil Engineering Forum Teknik Sipil Vol 17, No 2 (2007): MEI 2007
Publisher : Civil Engineering Forum Teknik Sipil

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Abstract

Unit hydrograph is one of flood design method that commonly used in Indonesia. Problems emerge in the unit hydrograph application including high rainfall variability both time and space, lack of automatic rainfall data needed for unit hydrograph derivation. However, the output of the catchment system called hydrograph that represent all the phenomena in the system is available. So, effect of rainfall variability on unit hydrograph and the possibility to derive unit hydrograph based on hydrograph data without rainfall data need to be studied. Unit hydrograph derivation is done by using different rainfall input i.e. single station, rainfall catchment and inverse effective rainfall derived based on hydrograph alone. The resulted unit hydrographs are then used for design flood calculation. Results show that the resulted unit hydrographs vary among the different rainfall inputs. The difference in peak relative to unit hydrograph derived based on average rainfall for Bedog, Code and Winongo catchments could reach -18%, -30% and -11%, respectively. This result indicates that in the catchment studied, the rainfall variability is relatively high. However, the difference in flood peak is quite small, that is up to -12% for all the catchments. There is a trend that the station closest to the catchment centroid gives small bias in design flood relative to the design flood computed based on average rainfall.
KAJIAN PERUBAHAN EROSI PERMUKAAN AKIBAT PEMBANGUNAN HUTAN TANAMAN INDUSTRI DI AREAL PENCADANGAN HTI KABUPATEN KETAPANG PROPINSI KALIMANTAN BARAT Saptarini N., C. Lestari; A. Kironoto, Bambang; Jayadi, Rachmad
Civil Engineering Forum Teknik Sipil Vol 17, No 2 (2007): MEI 2007
Publisher : Civil Engineering Forum Teknik Sipil

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Abstract

Allocated area for planted-forest in Ketapang Regency, especially in Durian Sebatang river basin and its surrounding are in critical condition with low land- productivity and poor hydrologic characteristic. These areas have to be conserved with vegetative method. One of the efforts to synergize soil and water conservation and economic interest is immediately to rehabilitate the critical areas with Planted-Forest (Hutan Tanaman Industri—HTI). Planted-forest system can be arranged to control the rate of erosion. The aim of this study is to predict the rate of erosion at the existing condition and the change of erosion rate at the planting-rotation system (cutting system) in the planted-forest of Acacia sp. The planting- rotations are 5 years, 6 years, 7 years and 8 years during the range of 11 years study. The research uses the version 3.3 of GIS Arc View program to make the land-unit map. The amount of surface erosion (sheet erosion) estimated base on the land-unit map. The calculation of the erosion rate uses the Modified USLE method (Snyder,1989), in which factors influencing the amount of surface erosion are Rain Erosivity (R), Land Erodibility (K), Length and Elevation of slope (LS) and Soil Conservation Factor and Planting System (VM). The results of the study show that the rate of erosion at the existing condition is 1,24 mm/year. Its a light danger erosion level, under the soil loss tolerance limits (2 mm/year). During the 11 first years of HTI development, the rate of erosion in planted forest with planting rotation of 5, 6, 7 and 8 years ranges from 0,91 mm/year to 2,66 mm/year. Its included in a very light to heavy erosion danger level. The lowest average erosion rate is found in the planting rotation of 7 year, continued by 8, 6 and 5 year. At first cycle, the rates of erosion in all planting rotation are more than the amount of existing erosion. Its caused by land clearing activity for plantation, but at further cycle, those are decrease until under the existing condition when the vegetation at conservation areas reach to an optimal growth. The rates of erosion in HTI can be controlled if we arrange the allocation of land utilization t consider by soil type. The reasonable planting-rotation of HTI with Acacia sp vegetation’s type to be applied in the research area is 6 years or 7 years. The optimal planting rotation is decided base on amount of erosion rate, soil stability, wood utilization and economic value. The expectation of this research can be contribute in soil conservation and social economic integrated development program.
PENGARUH ANGKUTAN SEDIMEN DASAR (BED LOAD) TERHADAP DISTRIBUSI KECEPATAN GESEK ARAH TRANSVERSAL PADA ALIRAN SERAGAM SALURAN TERBUKA Kironoto, Bambang Agus
Civil Engineering Forum Teknik Sipil Vol 17, No 2 (2007): MEI 2007
Publisher : Civil Engineering Forum Teknik Sipil

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Abstract

In sediment transport problems, such as the initial motion of sediment particles, scouring process, degradation process, etc., the information about the wall shear velocity, u*, is often needed. How the wall shear velocity variates in transversal direction, as the function of slopes and discharges, either for flows with and without bed load transport will be studied. The wall shear velocities, u*, are evaluated using the Clauser’s method, which is based on the velocity distribution data, due to the simplicity and the accuracy of the method. Hundred and twenty five velocity distributions data with five different slopes and five different discharges are used to study the wall shear velocity in transversal direction. The results of analysis show that the Clauser’s method still remains valid, and can be used to determine the wall shear velocity in transversal direction, as long as the velocity distributions data n the near wall region still follow the logarithmic velocity distribution. Closer to the wall, the shear velocity becomes to decrease, which is not influenced by the existence of bed load transport, as well as by the variations of slopes and discharges variations.
PENGARUH COMPACTION RATIO TERHADAP SIFAT PAPAN LANTAI PARTIKEL KAYU JATI DAN SENGON Widayanto, Widayanto; Morisco, Morisco; Prayitno, T.A.
Civil Engineering Forum Teknik Sipil Vol 17, No 2 (2007): MEI 2007
Publisher : Civil Engineering Forum Teknik Sipil

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Abstract

Wood particle board is one of building materials which can be used as floor like solid wood. To utilize particle boards with appropriate compaction ratio, study should be conducted to know the influence of compaction ratio on the particle board characteristics of two wood species namely teak and sengon, and the research result could be used as a base of the assessment to particle board for building. The preliminary test was done to know the density of teak and sengon wood. This study used teak and sengon wood particles with 10% by weight of particle urea formaldehyde adhesive UA-147. This study was arranged in the completely randomised design with factorial experiment. The factors in this experiment were compaction ratio and wood species, while the parameters which observed were density, water content, water absorption, thickness swelling, internal bonding, hardness, MOE, and MOR. The research result showed that the higher compaction ratio, the higher density, internal bonding, hardness, MOR and MOE of both species particle board, the higher thickness swelling, and the lower water absorption of sengon particle board. The highest average density of the teak particle board was 0,80 g/cm3 (J1K3) and 0,67 g/cm3 for sengon (J2K6). The highest average internal bonding of the teak particle board was 5,20 kg/cm2 (J1K3) and 5,85 kg/cm2 for sengon (J2K6). The highest average hardness of the teak particle board was 666,7 kg/cm2 (J1K3) and 533,3 kg/cm2 for sengon (J2K6). The highest average MOR of the teak particle board was 145,9 kg/cm2 (J1K3) and 162,7 kg/cm2 for sengon (J2K6). The highest average thickness swelling of the sengon particle board was 30,76% (J2K4) and 11,84% the lowest (J2K3). The highest average MOE of the sengon particle board was 18605,45 kg/cm2 (J2K6) and 22580,41 kg/cm2 for the teak (J1K3). The highest average water absorption of the sengon particle board was 170,30% (J2K1) and 72,12% the lowest (J2K6). With the same compaction ratio of the teak and sengon particle board, the teak wood species had the better physic and mechanic characteristics than sengon. Based on the comparation result with some industries standard of the particle board, it showed that particle boards J2K1, J2K2, and J2K3 did not correspond to some industries standard.

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