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This paper investigates the compressive strength of concrete in a 3-dimensional contact problem using the Discrete Element Method (DEM). This method was chosen because it can simulate the development of a single fracture up to massive fragmentation, including cracks pattern and coalition. The experimental test consisted of four cubes with 150x150x150 mm in dimensions, the constant of axial load applied to each specimen of 0.05Po up to 0.70Po. The data analysis has been carried out in Discrete Element and opensource three-dimensional code (YADE). The spherical Particles were used to the material models of concrete cubes. The pulse velocity parameter proposed to determine the behavior of the material during loading. The DEM and pulse velocity results illustrate the conformity of the relationship between stress and strain, deformation characteristics, and compressive strength of concrete.

This study describes the pattern of concrete damage to compressive and tensile strength on various of concrete quality using DEM (Discrete Element Method). Concrete was design as a uniform material in the three-dimensional analysis. Sphere particle is used to simplified the complex analysis. Laboratory testing is carried out to validate the performance of the DEM in the macroscopic model. Each variant has two specimens, the specimens consist of three different compressions, and the Brazilian splitting tensile test was 20MPa, 25MPa, and 30MPa. The test results show that the DEM analysis can model crack behavior under loads. The model was capable of predicting the performance of plain concrete with different qualities. The stress-strain curve, damage particle, velocity, and mechanical parameter of concrete quality were obtained. Finally, the uniform of spherical particle material is an alternative that can be proposed in the concrete laboratory-scale test modelling.

ABSTRAKPaper ini membahas tentang state of the art penyelesaian sengketa konstruksi di Indonesia yang meliputi jenis sengketa, indikasi potensi sengketa, dan perbandingan peraturan penyelesaian sengketa jasa konstruksi. Metode yang digunakan adalah mix method yang terdiri dari expert judgment, studi literatur dengan memperbandingkan riwayat penyelesaian perselisihan kontrak konstruksi mengacu kepada UU No.02/2017, Perpres No.16, UU No. 30 / 1999, dan PP No. 22/2020, dan Dispute Resolution Management Matrix (DRM-Matrix). Hasil analisis menunjukkan bahwa dua hal pokok penyelesaian sengketa yaitu pilihan penyelesaian sengketa dan penyelesaian sengketa di luar pengadilan (litigasi dan non litigasi). Penyempurnaan diberlakukan dalam PP No.22 Tahun 2020 yang menjelaskan tentang tahapan penyelesaian sengketa yang menyangkut mediasi, konsiliasi, dan arbitrase, juga terkait dengan penunjukkan dewan sengketa.Kata kunci: kontrak, konstruksi, perselisihan, state of the art ABSTRACTThis paper discusses of state of the art construction dispute resolution in Indonesia, which includes types of disputes, indications of potential disputes, and comparison of construction service dispute resolution regulations. The proposed method is a mixed-method consisting of expert judgment, literature study by comparing the history of construction contract dispute settlement referring to Law No. 02/2017, Presidential Decree No. 16, Law No. 30/1999, and PP. 22/2020, and the Dispute Resolution Management Matrix (DRM-Matrix). The results show that there are two main issues for dispute resolution, namely the choice of dispute resolution and dispute resolution outside the court (litigation and non-litigation). Improvements are enforced in Government Regulation No.22 of 2020 which explains the stages of dispute resolution involving mediation, conciliation and arbitration, as well as the appointment of a dispute board.Keywords: contract, constructions, dispute, state of the art

Objective: The development of a Self-Compacting Concrete (SCC) mixture requires a different composition compared to normal vibrated concrete. This experimental study was designed to propose a modification of the concrete mix design formula to produce an SCC mix that meets the specified requirements for both fresh and hardened concrete using Ground Calcium Carbonate (GCC) as local fine powder material. Methods: The research was carried out with a targeted compressive strength between 30 and 60 MPa. The materials that were used in this research were fine natural aggregate, crushed stone as a coarse aggregate with a maximum size of 19 mm, Portland pozzolan cement (PPC), GCC, freshwater, and high-range water reducer. The properties of fresh concrete were tested using the slump-flow test method, while the compressive strength test was carried out on 50 standard cylinders after 28 days of curing with water immersion. Results: Test results indicated that the compressive strength and fresh properties of SCC significantly depend on the water content, the water/cement ratio, the volume ratio between water to the total binder, and the weight ratio between the GCC and Portland cement. Conclusion: Furthermore, using the experimental data based on varied water content and binder compositions produces equations with a good fit for SCC mix design in the compressive strength range between 30 MPa to 60 MPa.

This study presents a simple NDT method with Ultrasonic Pulse Velocity (UPV) to detect repair of R/C columns by injection and grouting. In this paper, the technique applied is mainly based on the use of epoxy under pressure into the R/C column crack system for lightly damage, whereas grouting used for repair of medium and heavy damaged R/C columns. The specimen is initially charged to increase axial loads up to 0.1P0, 0.3P0 and 0.5P0. After repair, all specimens were retested with the same method. The test results show that the repair technique is in a good category with a pulse velocity value of 4.21km/s. Pulse velocity transmitter analysis provides conceptual support to increase column capacity through repair methods. Direct methods can be recommended for post-repair structural strength with high accuracy. This method is a potential candidate for future development, especially to predict the level of damage and building rehabilitation after an earthquake.

Shear walls are structural walls designated as part of an earthquake force-resisting system, which also serves to increase the stiffness of the structure and absorb large shear forces as the height of the structure increases. When shear walls are placed in the right and strategic position, shear walls can be used economically to provide horizontal load resistance. In this paper, the 7-storey symmetrical building structure is modelled and analyzed using ETABS v.9.7.4 software. Analysis was carried out on four structural models with variations in the proposed shear wall locations. The model without shear walls was used as a controller for the normal model. This paper aims to optimize the location of the shear wall in a 7-storey symmetrical building structure. Furthermore, the results of the analysis of the structure of the building without shear walls and variations in the location of the shear walls were obtained using the ETABS v.9.7.4 software. The analysis results show that model 3 is a better location for shear walls to be applied to the review structure.   Abstrak Shear wall merupakan dinding struktur yang ditetapkan sebagai bagian dari sistem penahan gaya gempa, juga berfungsi menambah kekakuan struktur dan menyerap gaya geser yang besar seiring dengan semakin tingginya struktur. Ketika shear wall diletakan pada posisi yang cocok dan strategis, shear wall dapat digunakan secara ekonomis untuk menyediakan tahanan beban horisontal yang diperlukan. Dalam tulisan ini struktur gedung simetris 7 tingkat dimodelkan dan dianalisis menggunakan software ETABS v.9.7.4. Analisis dilakukan pada 4 model struktur dengan variasi letak shear wall yang diusulkan. Untuk model normal yaitu model tanpa shear wall digunakan sebagai pengontrol. Tulisan ini bertujuan untuk mengoptimalkan letak shear wall pada struktur gedung simetris 7 tingkat. Selanjutnya, hasil analisis struktur gedung tanpa shear wall dan dengan variasi letak shear wall menggunakan software ETABS v.9.7.4 telah diperoleh. Hasil analisis menunjukan bahwa model 3 merupakan letak shear wall yang lebih baik untuk diterapkan pada struktur tinjauan.

Various structural factors that contribute to damage during an earthquake are vertical irregularities, irregularities in strength and stiffness, mass irregularities, torsional irregularities, and so on. Over the past decade, performance-based design (PBD) procedures have become one of the most critical areas in earthquake engineering. The pushover procedure is divided into two parts; the first is the displacement target for the erected building. The target is the estimated displacement of the top of the building when exposed to the design earthquake excitation. Then a pushover analysis is carried out on the building until the top removal is equal to the target displacement. Second is the type of controlled force in which the total amount of force acting is estimated and applied to the structure, and analysis is carried out. The various performance levels for a building are expressed in terms of the base shear carried versus the roof displacement. If all the plastic hinges formed are within the CP limit, the structure is said to be safe. On the other hand, if the plastic hinge formed exceeds the CP limit, the structure is said to have collapsed. This paper proposes a 2D reinforced concrete frame with three models with variations of vertical irregularity. This paper aims to see the nonlinear behavior of reinforced concrete frames with vertical irregularities through the pushover method using SAP2000 software. Furthermore, the analysis results show that the skeleton is susceptible to increasing vertical irregularity. As the vertical irregularity increases, the percentage of the plastic hinge crossing the boundary increases. The analysis results also show that model 2 has better behavior.