ANALISIS ANGKUTAN SEDIMEN DASAR (BED LOAD) PADA SALURAN IRIGASI MATARAM YOGYAKARTA

In the last decade, the problem that has occurred in the Yogyakarta Mataram irrigation channel is the occurrence of sedimentation in the channel. This has an impact on reducing the cross-sectional discharge capacity of the canal and resulting in the supply of irrigation discharge to agricultural areas to be not optimal, so that agricultural productivity in the Mataram Irrigation Area will also not be optimal. The sediment transport (bed load) that occurs in an open channel can be approached using the empirical equation, including the Einstein, Meyer - Peter Muller and Frijlink equations. Sediment transport events that occur in the channel are stated based on the magnitude of the flow shear stress which exceeds the critical shear stress of the sediment particles. The quantity of sediment transport in the channel is stated on the logarithmic curve of the relationship between the froude number (fr) to the sediment transports (qb). The Curve explains that the increase in the froude number (fr) that occurs on each section of the channel will be directly proportional to the increase in the quantity of transport sediment (qb). The largest sediment transport occurred at the site of the Gambang and Nambongan channel section with a prediction of sediment transport of 3.57 m3/day and 3.67 m3/day, respectively. Thus, the potential for sediment transport that will settle in the downstream area is 3.67 m3/day.

KECEPATAN GELOMBANG GESER (VS) DAN KETEBALAN SEDIMEN (H) DI KABUPATEN KLATEN DARI DATA MIKROTREMOR

Research on Shear Wave Velocity (vs) and Sediment Thickness (h) in Klaten Regency, Central Java from field microtremor data aims to determine the thickness of sediment or soft sediment as one factor of high and low earthquake vulnerability. Microtremor data was collected using a three-component TDS 303 seismometer covering 111 measuring points in the Klaten Regency area. In this study, the sediment thickness was calculated using the equation shear wave velocity (vs) divided by four times the dominant frequency (fg). The dominant frequency (fg) value is obtained from the HVSR curve. In contrast, the shear wave velocity value (vs) used in this study is the inversion value of the HVSR curve, which is modeled based on borlog data at the Wedi Church, equated for all measurement points. The map of the shear wave velocity distribution at each microtremor measuring point has a vs value; this value is used to calculate the thickness of the sediment at each end. So that the distribution of the thickness value of the sediment at each point is obtained, then a thickness map is made covering the study area. The results showed that, in general, the research area has a Vs value in the effects of the HVSR curve inversion ranging from 130 m/s to 570.83 m/s, Vs average 275.68 m/s. The areas with vs are relatively high in the southern part of Gantiwarno, Wedi, and Bayat subdistricts directly adjacent to Gunung Kidul. Areas with relatively low-value of vs are in Prambanan Subdistrict, Northern Wedi Subdistrict, Trucuk Subdistrict, Jogonalan Subdistrict, South Klaten District, Central Klaten District, and Kalikotes Subdistrict. For sediment thickness (h) ranges from 5.105 m to 113.648 m. Areas with relatively high sediment thickness are located in parts of Wedi Subdistrict with a thickness of up to 110 m. Areas with medium thickness (around 60 to 90 m) are in the Gantiwarno sub-district, Prambanan district, and the southern part of the Jogonalan sub-district. In Bayat District, it has a low thickness (about 5 to 30 m) located in the proves and mountains of the Paseban area and the tomb of Sunan Pandanaran. The result shows that areas with high sediment thickness, namely in Wedi District, have a high level of earthquake vulnerability.

KOMPARASI KAPASITAS NOMINAL LENTUR PELAT KOMPOSIT BETON-DEK BAJA ANTARA METODE ULTIMIT, TEGANGAN KERJA, DAN SDI-ANSI 2017

Today, the most efficient slab construction method is the concrete-steel deck composite slab because there is no need to remove the deck after the concrete casting process. Nevertheless, reinforced concrete standard code (SNI 2847:2019) not emphasized a specific method to calculate the concrete-steel deck slab's nominal capacity. The code is embraced by the plastic method analysis, which is calculated the nominal capacity of the structure on the ultimate condition. However, several laboratory tests reveal a slip behavior between the concrete and steel deck before the slab reaches its ultimate condition. Therefore, alternative methods are needed to analyze the nominal capacity of concrete-steel deck slab. This study compares three different nominal capacity analysis methods to a laboratory test result. Those methods are ultimate, working stress, and SDI-ANSI (2017). The average error value of those three methods compared to laboratory test results in 35,57%, 9,48%, and -10,31% for ultimate, working stress, SDI-ANSI (2017) consecutively.it can be concluded the working stress method is the most accurate. However, SDI-ANSI (2017) is the conservative one, while the ultimate method is not recommended to analyze the concrete-steel deck slab's nominal capacity.

PENGARUH FAKTOR GEOMETRIK SUMUR RESAPAN TERHADAP PERENCANAAN DIMENSI SUMUR RESAPAN DAN PENGURANGAN LIMPASAN PERMUKAAN

To solve the problem of flooding and to conserve groundwater, many infiltration wells have been built. The dimensions and number of infiltration wells are influenced by the geometric factor of an infiltration well. Therefore, this paper discusses the influence of infiltration well geometric aspect on the dimensional planning and the number of infiltration wells needed and feasible to build based on the existing land limitations. The planning of infiltration wells uses the Sunjoto method. The study location is in the UII integrated campus. The rainfall data were taken from the Prumpung station in 1998 - 2016. The more significant the infiltration well geometric factor, the smaller the number and dimensions of infiltration wells. For example, in the D3 Ekonomi complex, for a type of infiltration well with a diameter of 1.5 m and a height of 4 m, with "F = 2π" R, eight units are needed, while an infiltration well with "F = " "π" ^2 R require seven units. Likewise for other complexes. With the limited land available, the greater the infiltration well geometric factor used, the reduction in surface runoff is not much change, almost the same, namely 59.73 % with F = 2πR (or F=4.7124 m) and 59.79 % with F = π^2*R (or F=7.4022 m).