There are many applications of Genetic Algorithm (GA) and Harmony Search (HS) Method for solving problems in civil engineering design. The question is, still, which method is better for geometry optimization of a steel structure. The purpose of this paper is to compare GA and HS performance for geometric optimization of a steel structure. This problem is solved by optimizing a steel structure using GA and HS and then comparing the structure’s weight as well as the time required for the calculation. In this study, GA produced a structural weight of 2308.00 kg to 2387.00 kg and HS scored 2193.12 kg to 2239.48 kg. The average computational time required by GA is 607 seconds and HS needed 278 seconds. It concludes that HS is faster and better than GA for geometry optimization of a steel structure.

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According to SNI 03-2834-2000, concrete is a mixture of Portland cement, fine aggregate, coarse aggregate, and water with or without added materials to form a solid mass. Many studies have developed the building blocks of concrete mixtures to improve their quality and properties of concrete mixtures. In this study, lightweight brick waste from the rest of the construction project was used with a first refining process to pass a 0.3 mm sieve as a fine aggregate substitution mixture. The test object used is a cylinder with a size of 15 cm x 30 cm with variations in substitution of lightweight brick powder (SBR) 0%, 10%, 15%, 20%, and 30%. The method of calculating and testing materials and concrete specimens is guided by SNI 03-2834-2000. It was found that the substitution of SBR had a varying effect on the compressive strength of concrete. The maximum compressive strength was found at 21.44 MPa at 28 days, with an optimum SBR of 15% for fine aggregate. ABSTRAK Menurut SNI 03-2834-2000, beton adalah campuran semen, agregat halus, agregat kasar, dan air dengan /tanpa bahan tambah yang kemudian membentuk massa padat. Sebagai upaya meningkatkan kualitas dan sifat-sifat campuran beton, banyak penelitian yang mengembangkan bahan-bahan penyusun campuran beton. Dalam riset ini, limbah bata ringan yang berasal dari sisa proyek pembangunan diteliti dengan proses penghalusan terlebih dahulu hingga lolos ayakan 0,3 mm sebagai campuran substitusi agregat halus. Benda uji yang digunakan berbentuk silinder ukuran 15 cm x 30 cm dengan variasi substitusi serbuk bata ringan (SBR) 0%, 10%, 15%, 20%, dan 30%. Metode perhitungan dan pengujian material serta benda uji beton berpedoman pada SNI 03-2834-2000. Dari penelitian ini didapatkan hasil bahwa subtitusi SBR memiliki pengaruh yang bervariasi pada nilai kuat tekan beton. Nilai kuat tekan tertinggi sebesar 21,44 MPa pada umur 28 hari dengan persentase optimum subtitusi SBR sebesar 15% terhadap agregat halus.

Rangka batang merupakan susunan elemen yang membentuk segitiga atau kombinasi segitiga sehingga membentuk struktur rangka yang stabil. Untuk mendapatkan desain struktur yang optimal diperlukan metode analisis dan desain struktur yang tepat dan mudah. Metode keseimbangan titik simpul dan metode cremona merupakan metode statika yang pada umumnya digunakan untuk menganalisa struktur rangka batang, namun menjadi cukup rumit apabila metode ini diterapkan pada rangka batang statis tak tentu yang lebih kompleks karena perpindahan titik simpul yang telah berdeformasi cukup sulit untuk didapat. Di lain pihak metode elemen hingga dapat dengan mudah diaplikasikan pada struktur statis tertentu maupun statis tak tentu. Program aplikasi FEM dibuat untuk proses analisis struktur dengan menggunakan metode elemen hingga, menggunakan program Visual Basic V.6.0 kemudian akan digunakan untuk menganalisa 5 model struktur rangka baja 2D. Model struktur rangka baja yang sudah disiapkan akan dianalisa menggunakan program aplikasi FEM, dan kemudian hasil analisa tersebut akan dibandingkan dengan hasil analisa menggunakan program SAP2000 untuk mendapatkan prosentase perbandingan hasil analisa dari kedua program. Dari hasil analisa yang telah dilakukan dapat ditarik kesimpulan bahwa analisa struktur menggunakan program aplikasi FEM memerlukan waktu yang lebih singkat daripada program SAP2000, serta prosentase perbandingan hasil analisanya untuk analisa displacement joint pada sumbu X antara 0 % sampai dengan 5,5482 %, sedangkan pada sumbu Y antara 0 % sampai dengan 5,5448 %. Untuk perbandingan hasil analisa member force adalah 0%. Untuk perbandingan hasil analisa joint reaction pada sumbu X dan Y adalah 0 %. Dan untuk perbandingan hasil analisa member stress adalah 0 %.

Indonesia is located in a subduction zone formed by the collision of continental and oceanic plates. Many volcanoes form as a result of these conditions along the arc. Springs on the volcano's slopes are widely used for domestic, irrigation, and industry water use. Investigating the characteristics of aquifers and springs is essential to ensure groundwater sustainability by providing a robust geological framework. Meanwhile, groundwater in a volcanic geological setting has good quality characteristics because of its occurrence process, which interacts with many minerals in pyroclastic rocks that act as aquifers. The study area is located in the Lido Catchment Area (LCA), which is situated between two distinct volcanic slopes. Geological and morphometric analysis at LCA is the basis of important information relating to its hydrogeological systems. The analysis of thin rock sections and parameters of the physical properties of water in groundwater springs supports our research. We applied a comprehensive geological and morphometric analysis to obtain detailed information about the aquifer. This study aimed to determine the characteristics of aquifers in pyroclastic rocks and their relationship to the formation of springs. From the research conducted, the characteristic of water can be distinguished based on the geological conditions of its constituents. There are 6 different lithological characteristics in the study area: polymictic breccia, monomictic breccia, lapilli, lapilli tuff, coarse tuff, and fine tuff. From the lithology variations obtained, breccia, lapilli, and coarse tuff can play a good role as aquifers. Geological correlations and groundwater systems in the study area show groups of superficial, mixed, and alteration springs. The system of water flows in aquifers through inter-grains or rock fractures. The types of springs in LCA are dominated by depression and fracture types. These results are fundamental information for understanding hydrogeological systems in future volcanic geological settings.