PEMBUATAN PETA MIKROZONASI GEMPA KOTA SEMARANG MELALUI PENGEMBANGAN PROGRAM SEISMIC HAZARD DENGAN MEMPERTIMBANGKAN KONDISI FRAGILITY BANGUNAN

The new Indonesian code for building design, SNI 1726:2012, has been issued recently. It follows the concept of Risk-Adjusted Maximum Considered Earthquake MCE R used by ASCE 7-10 and it provides maps of MCE R for the whole Indonesian Country. Development of seismic risk microzonation of Semarang City is required for disaster preparedness and hazard mitigation. The purpose of this research is then to propose the seismic microzonation of Semarang City based on the seismic hazard analysis, site specific response analysis and risk assessment. The seismic hazard analysis is adapted from ASCE 7-10 to produce MCE R ground motion at bedrock level for the whole area in the city by combining the results of deterministic, probabilistic seismic hazard analysis, and fragility curves of buildings. The analysis was performed by using calculation procedures, seismic source model, attenuation functions, and geological and seismological data previously used to develop national seismic hazard and risk maps by Team for Revision of Seismic Hazard Maps of Indonesia 2010. The site response analysis and risk assessment were conducted by carrying onedimensional ground response analysis. Geotechnical parameters are interpreted from previous and recent measurements and depth of engineering bedrock is estimated based on Single Station Feedback Seismometer measurement. Two engineering bedrock elevation models were performed to obtain the distribution of site response such as peak ground acceleration (PGA), spectral acceleration at ground surface and amplification factor due to ground motions at bedrock. The seismic microzonation is carried out by selecting time histories of ground motion records for input motions in one-dimensional propagation analysis. Five ground motions for all sources and five ground motions for shallow crustal fault sources (with magnitude ranging from 6 to 7 and maximum distance 20 km) are collected from worldwide historical earthquake database records. Site response analysis is then conducted for each ground motion to obtain peak ground acceleration, spectral acceleration and amplification factor. Keywords: Seismic Microzonation, Seismic Hazard Analysis, Site Specific Response Analysis, Single Station Feedback Seismometer Measurement

ERGONOMI PADA METODA KERJA UNTUK MENINGKATKAN PRODUKTIVITAS TENAGA KERJA DI BIDANG KONSTRUKSI

Produktivitas adalah isu penting dalam industri jasa konstruksi, karena berkaitan langsung dengan biaya dan waktu pelaksanaan proyek konstruksi. Dari berbagai faktor yang mempengaruhi produktivitas pekerjaan konstruksi, tenaga kerja merupakan faktor yang paling sulit diprediksi. Di Indonesia standar produktivitas dan tingkat efisiensi pekerja telah ditentukan dalam Standar Nasional Indonesia (SNI), namun belum ditetapkan metoda kerja yang baku dan efisien, setiap pekerja melakukan suatu pekerjaan dengan metoda yang berbeda, sehingga produktivitas yang dihasilkan berbeda-beda. Pada penelitian ini analisis produktivitas tenaga kerja dilakukan secara komprehensif dengan meninjau 4 aspek, yaitu : analisis efisiensi waktu kerja dan produktivitas yang diukur dengan Methode Productivity Delay Model (MPDM), analisis ergonomi dan ekonomi gerakan (motion economic), analisis tingkat beban kerja, analisis nyeri otot akibat kerja (musculosceletal disorder). Keempat aspek ini dipilih untuk meningkatkan produktivitas tenaga kerja, dengan cara perbaikan pada aspek manajemen melalui peningkatan efisiensi waktu kerja dan pengaturan waktu istirahat, serta perbaikan performansi tenaga kerja dengan penerapan prinsip ergonomi dan ekonomi gerakan. Ergonomi menjadi instrumen analisis utama, dengan hipotesis bahwa perbaikan aspek ergonomi akan memperbaiki produktivitas tenaga kerja. Pada penelitian ini dilakukan pemilihan pada pekerjaan pasangan bata dan plester, pekerjaan pasangan keramik lantai dan dinding, dan pekerjaan pengecatan. Desain perbaikan metoda kerja selanjutnya diujicobakan kepada pekerja dan dihitung produktivitas yang dihasilkan. Untuk menguji validitas hasil, dilakukan uji statistik dengan T-Test terhadap produktivitas tenaga kerja pada kondisi awal (eksisting) dan produktivitas sesudah dilakukan perbaikan metoda kerja. Dari hasil penelitian diperoleh kenaikan efisiensi waktu dengan metoda perbaikan, yaitu 88,74% pada pekerjaan pasangan bata, 88,29% pada plester, 86,16% pada pasangan keramik, dan 86,75% pada pengecatan. Efisiensi ini lebih tinggi dari standar efisiensi yang ditentukan dalam SK SNI, yaitu 71,40%. Perbandingan produktivitas dengan standar SNI untuk setiap jenis pekerjaan adalah : pasangan bata 1,6 m 2 /jam (SNI 1,45 m 2 /jam), plester 1,45 m 2 /jam (SNI 0,95 m /jam), pasangan keramik 0,56 m 2 /jam (SNI 0,42 m 2 /jam), pengecatan 2,57 m 2 /jam (SNI 2,28 m /jam). Beban kerja yang dialami pekerja jika dirujuk pada Keputusan Menteri Tenaga Kerja Nomor 51 Tahun 1999 tergolong ‘ringan’, dan berdasarkan kategori nilai Cardio Vasculer Load yang diintrodusir oleh Manuaba & Vanwonterghem (1996) masuk dalam kategori ‘tidak terjadi kelelahan’. Dapat disimpulkan bahwa pekerja belum maksimal bekerja, dengan demikian produktivitas masih dapat ditingkatkan. Cara kerja yang dipakai pekerja masih mengabaikan aspek ergonomi yang mengakibatkan pekerja mengalami keluhan pada otot-otot rangka (musculoskeletal). Berdasarkan kajian terhadap sertifikasi Ahli K3 Konstruksi yang merupakan bagian integral dari sertifikasi tenaga kerja konstruksi, ergonomi belum menjadi kompetensi yang harus dimiliki. Padahal di dalam SKKNI (Standar Kompetensi Kerja Nasional Indonesia) penerapan K3 (Keselamatan dan Kesehatan Kerja) dikategorikan sebagai Kompetensi Umum, yang artinya harus dimiliki oleh setiap orang yang ingin memperoleh sertifikat SKKNI. Kata kunci : beban kerja, efisiensi waktu kerja, ergonomi, produktivitas, sertifikas

ANALISIS DINAMIS DINDING PENAHAN TANAH AKIBAT BEBAN DINAMIS

In general, the failure of retaining wall construction is influenced by the geometry of the construction of retaining wall, physical and mechanical properties of the soil embankment and/or subgrade and static and/or dynamic load. In a dynamic analysis of the stability of retaining wall, landslide surface behind the retaining wall are calculated based on assumptions. It is required to develop a method that is appropriate in site planning construction of retaining wall due to the dynamic loads by considering the form of sliding soil behind retaining wall. The results of this study are expected to determine the role of these parameters to the movement of the material behind the wall due to the sinusoidal dynamic load. This research used the movement of materials with equivalent static analysis to analyze the stability of the retaining wall. This study was conducted to the small-scale test of a retaining wall model in the laboratory. This models used gravity of retaining wall, which was made of concrete and was placed on dry sand with a trapezoid-shaped a height of 20 centimeters, width of peak 2 centimeters and width of below 10 centimeters and cantilever with a height of 18.3 centimeters, width of 9.3 centimeters that is placed on dry sand that can pass through sieve No. 4 and retained on sieve No.100. Variations in the relative density of the sand used for testing is a relative density (DR) of sand of 30%, DR of 60% and DR of 75% to model gravity and DR of 30%, DR of 55% and DR of 70% for the cantilever model. The model placed in the glass box of a length of 2 meters, width of 0.4 meters and height of 1 meter. The model vibrated using a shaking table that is moved horizontally with variation of the vibration frequency (f) and the amplitude of vibration (A). Sinusoidal dynamic acceleration response is recorded using an accelerometer. Granular soil displacement at some point also be monitored during the test. The results showed that the shape of the field of material movement behind the retaining wall is influenced by DR of sand, type of retaining wall and the sinusoidal dynamic acceleration (a maks ). The DR of sand effect on the area and shape of material movement field by certain a maks . The lower of affect DR then the wider and deeper the field of material movement. The relationship of a maks against the width of material movement and a maks against the height of material movement is linear. The parameter of f is more dominant influence on the a maks compared with A. The percentage of increase in a maks be two-fold when the f be improved. If the A is increased then the increase of a maks be proportional to the increase in A. The parameter of f has a dominant effect on the height of the material movement field. The greater of f then the greater of height of material movement field. The parameter of A has a dominant influence on the width of the material movement field. The larger of A getting wider the field of material movement that occurred. By delivering three variations a maks of 0,221g, 0,245g and 0,27g the safety factor of overturning (SF overturning ) for both models showed a decrease due to increased of the material movement bandwidth, as a result of the increase in the a maks . By increasing the DR, then the SF overturning decreases follow the trend of their respective functions. the SF sliding for two types of models show a decline, along with the increase of vast of material movement field. The safety factor of sliding (SF sliding ) increases follow the trend of their respective functions if the DR increased. Keywords: the type of retaining wall, dynamic acceleration, material movement field shapes, relative density of sand, vibration frequency, vibration amplitude

PERILAKU MATERIAL DAUR ULANG LAPIS PONDASI PERKERASAN JALAN YANG DISTABILISASI DENGAN SEMEN DAN POZOLAN ALAM

Cement Treated Recycled Base (CTRB) is a compacted pavement base layer material that was developed to reuse recycled materials for the purpose of conservation of natural resources, minimizing construction cost, and to be more environmentally friendly construction compared to the conventional pavement base layer materials. The objective of this research is to explore the influences of the allowable proportions of Natural Pozzolan (trass) in CTRB mixes as partial replacement amounts of Portland cement in improving the physical properties of the CTRB mixtures to improve the in-place field performance of the pavement. The research efforts consist of various laboratory experimental methods including physical properties of materials, mixture compaction parameters, and stiffness/strength evaluations in relation to the performance parameters of the mixture using Natural pozzolan (trass) as a cement replacement. The compositions of the mixtures were 40% RAP and 60% RAM, and 60% RAP and 40% RAM with cement contents of 2%, 4% and 6% substituted by 0%, 15% and 30% Natural Pozzolan respectively. The total number of samples tested for the physical properties and stiffness/strength testing were 378. The results of this study indicate that the amount of Natural pozzolan on CTRB mixture can improve the physical properties of the mixtures by improving the mechanical properties of the samples. The results show that the increase in density (γd) or the decrease in porosity (η) in the samples as positive impacts to the stiffness/strength parameters that exceed the parameters of the control mixtures stabilized with cement only. The optimal CTRB mixture performances are from 15% natural pozzolan substitution to 6% cement for 40% RAP and from15% and 30% Natural pozzolan substitution to 6% cement for 60% RAP mixtures. In this study, an equation was developed to show the relationship between strength (qu) and the ratio between the porosity η to the cementitious material content (CIV*) based on the Natural pozzolan efficiency factor. This equation can be used to determine a proportion of cementitious material needed for a CTRB mixture design to achieve a designated strength. Key words: CTRB, Natural pozzolan, UCS, ITS and CB

Stabilisasi Tanah Lempung dengan Mengunakan Larutan Asam Sulfat (H2so4) pada Tanah Dasar di Daerah Godong - Purwodadi Km 50 Kabupaten Grogogan

An expansive clay soil material that is composed of various minerals include kaolinite, montmorillonite and illite group. Mineral montmorilinite have the sensitivity to the effects of the water is very easy to expand and contract. High and low levels of development (swelling) and shrinkage (shrinkage) expansive clay is determined by the high and low content of montmorillonite on expansive clay granules. Because of these properties are very high content of montmorillonite often cause problems in the building. This study uses a solution of sulfuric acid (H2SO4) as a stabilizer through the compaction process Modified Proctor on OMC Proctor standard by the number of collisions each is 10 x, 25 x and 56 x, and the amount of additional water in cc on dry ground, with variations in increments of 100%, water by 90%:10% H2SO4, water by 80%: 20% H2SO4 and water by 90%: 30% H2SO4. This research was conducted testing-testing in the laboratory include: physical properties, mechanical properties. swelling pressure, swelling potential and CBR with curing and no curing. Results of the test-the test, can increase the value of physical and mechanical properties, while pergujian against swelling pressure and swelling potential is not significantly increased

SISTEM KEUANGAN SYARIAH UNTUK PENINGKATAN INVESTASI SWASTA PADA PEMBIAYAAN INFRASTRUKTUR DI INDONESIA

Investasi sangat dibutuhkan untuk menopang pertumbuhan ekonomi Indonesia lebih dari 7 persen setahun. Pembangunan Infrastruktur transportasi, sumber daya air dan perumahan di Indonesia kenyataannya hanya 30% yang dapat didukung oleh dana APBN dari rencana. Sehingga untuk mendukung pertumbuhan ekonomi peran investor swasta sangat diharapkan. Kenyataan dalam realisasi dari peran investor swasta untuk mendukung kekurangan dana tidak sesuai harapan. Sehingga diperlukan sistem investasi selain sistem keuangan konvensional berdasarkan bunga yang berlaku sekarang dengan menggunakan sistem keuangan syariah yang berdasarkan bagi hasil. Dengan metode analisa secara kwantitatif, studi literatur dalam rangka mendapatkan informasi dari sumber primer dan sekunder. Dari hasil penelitian yang telah dilakukan dari komparasi konsep keuangan syariah untuk pembangunan infrastruktur dengan model BTO (Build Transfer Operate) dengan sistem keuangan konvensional sekarang menujukkan hasil penggunaan sistem keuangan syariah signifikan. Diberlakukan sistem keuangan syariah dan banyaknya investor muslim yang tidak setuju dengan sistem bunga dari keuangan konvensional akan menanbah minat investor dan negara muslim dalam investasi infrastruktur di Indonesia