Earthquake Resistance Optimization and Evaluation of Bridge Piers Structural Form and Dimensions Based on Demand to Capacity Ratio and Yielding Points of Force-Displacement

The evaluation of structural safety must be taken after each earthquake. The importance losses of life and materials carries the significance of the works in the field of earthquake engineering. The purpose of this study was to optimize and evaluate the earthquake resistance of bridge piers by adopting different cross-section forms and dimensions for bridge supports under earthquake action. Two methods of seismic design were used in the optimization and evaluation process. These methods were demand to capacity ratio (DCR) and yielding point. The results of demand to capacity ratio shown that the values of DCR for all piers forms models were increased when the dimension of pier cross section were increased and the values of DCR became less than 1.0, indicating that the increasing in dimensions leading to rise the capacity of bridge supports to carry the earthquake loads in transverse and longitudinal direction. Comparing with models, solid wall pier form had the lower value of DCR, indicating that solid wall piers were suitable in the design of bridge supports to resist the lateral loads of earthquake and it has enough stiffness and capacity under earthquake action. The results of performance points shown that the yielding points were increased when the dimensions of piers were increased for all piers form in transverse and longitudinal direction. The maximum values were appeared within support No. 1 and support No. 4. Solid wall form of pier had the higher values of yielding points, meaning that this type of piers form had higher seismic capacity and it will resist the earthquake action more than others piers form. This study recommended that to use third model for each pier form in the design of bridges structures to resist the earthquake load. Also this study was recommended to use solid wall piers as supports in construction of bridge structure within areas had earthquake action.

Pengaruh Klasifikasi Kelas Situs Menurut SNI 1726-2019 Terhadap Keruntuhan Progresif pada Struktur Gedung Tidak Beraturan

Seiring perkembangan teknologi konstruksi gedung, pembangunan gedung bertingkat dengan struktur tidak beraturan semakin bertambah demi memenuhi aspek estetika gedung maupun akibat keterbatasan lahan. Bentuk struktur tidak beraturan ini berpengaruh terhadap keruntuhan progresif gedung. Selain aspek desain, pada perencanaan gedung beban gempa harus direncanakan dengan peraturan baru yang berlaku yaitu SNI 1726-2019. Salah satu perubahan yang terjadi pada SNI 1726-2019 adalah klasifikasi kelas situs. Penelitian ini bertujuan untuk mengkaji pengaruh klasifikasi kelas situs terhadap keruntuhan progresif struktur gedung tidak beraturan. Penelitian ini dilakukan dengan menganalisis elemen struktur berupa kolom dan balok sebelum dan sesudah menghilangkan salah satu kolom struktur berpedoman pada General Services Administration (GSA) dengan beban gempa yang bekerja beban gempa statik ekivalen pada keempat klasifikasi kelas situs yaitu SB (Batuan), SC (Tanah keras), SD (Tanah sedang) dan SE (Tanah lunak). Pemeriksaan kekuatan struktur menggunakan perangkat lunak berbasis elemen hingga untuk mengetahui nilai Demand Capacity Ratio (DCR), Bending Moment Ratio (BMR) dan Robustness Indicator (R). Struktur dikatakan mengalami keruntuhan progresif apabila nilai DCR > 1,5. Dari hasil analisis diketahui nilai DCR dari kelas situs SB ke kelas situs SE mengalami kenaikan sedangkan nilai BMR mengalami penurunan. Hasil analisis juga menunjukkan bahwa keruntuhan progresif tidak terjadi pada keempat kasus kegagalan kolom dan perbedaan kelas situs terhadap gaya aksial dan momen, namun terjadi terhadap gaya geser. Nilai Robustness Indicator (R) yang didapat mendekati sama dengan satu (R≈1), nilai tersebut mengindikasikan bahwa penyaluran beban berjalan dengan normal.

ANALISIS KINERJA TIANG DENGAN VARIASI KEMIRINGAN DI DERMAGA “SJ” BANDAR LAMPUNG

The design of the jetty cannot be separated from the use of piles as a foundation that supports the upper structure. The pile configuration affects the strength and stability of the structure. It may consist of only vertical piles or a combination of vertical and batter piles. This study analyzes and compares 10 types of pile configurations intending to determine the best pile configuration among the types analyzed. Type 1 is a pile configuration that is in accordance with the field planning of “SJ” jetty which consists of only vertical piles and type 2 to type 10 is a pile configuration that consists of a combination of vertical and batter piles with a slope ranging from 1H:12V to 1H:4V. The best configuration is determined based on the strength (capacity ratio), stiffness (deflection that occurs), and the axial bearing capacity of the pile. The process of modeling and analyzing the pile configurations are done using Midas Gen. The results showed that pile configuration type 8 with a combination of vertical and batter piles with a slope of 1H:6V is the best configuration with the smallest deflection and the axial forces of the vertical and batter piles are almost equal.ABSTRAKDesain dermaga tidak dapat dipisahkan dari penggunaan tiang sebagai fondasi yang menyangga struktur bagian atas. Konfigurasi tiang berpengaruh pada kekuatan dan stabilitas dari struktur dermaga. Konfigurasi tiang dapat terdiri dari tegak seluruhnya maupun kombinasi antara tiang tegak dan miring. Penelitian ini menganalisis dan membandingkan 10 tipe konfigurasi tiang dengan tujuan mendapatkan konfigurasi tiang terbaik di antara tipe-tipe yang dianalisis. Tipe 1 adalah konfigurasi tiang yang sesuai dengan perencanaan dermaga “SJ” berupa tiang tegak seluruhnya dan tipe 2 hingga tipe 10 adalah konfigurasi kombinasi tiang tegak dan miring dengan kemiringan 1H:12V hingga 1H:4V. Konfigurasi tiang terbaik ditentukan berdasarkan kekuatan (capacity ratio), kekakuan (defleksi yang terjadi), dan daya dukung aksial tiang. Model dan proses analisis dari seluruh konfigurasi tiang menggunakan program Midas Gen. Hasil analisis menunjukkan bahwa konfigurasi tiang tipe 8 dengan kombinasi tiang tegak dan miring dengan kemiringan 1H:6V adalah konfigurasi terbaik dengan defleksi terkecil serta gaya aksial tiang tegak dan miring yang hampir sama.

Developing Guidelines for Implementing Transit Signal Priority and Freight Signal Priority Using Simulation Modeling and a Decision Tree Algorithm

Transit signal priority (TSP) and freight signal priority (FSP) allow transportation agencies to prioritize signal service allocations considering the priority of vehicles and, potentially, decrease the impact signal control has on them. However, there have been no studies to develop guidelines for implementing signal control considering both TSP and FSP. This paper reports on a study conducted to provide such guidelines that employed a literature review, a simulation study, and a decision tree algorithm based on the simulation results. The guideline developed provides recommendations in accordance with the signal timing slack time, the proportion of major to minor street hourly volume, hourly truck volume per lane for the major street, hourly truck volume per lane for the minor street, the proportion of major to minor street hourly truck volume, the proportion of major to minor street hourly bus volume, the volume-to-capacity ratio for the major street, and the volume-to-capacity ratio for the minor street. The guideline developed was validated by implementing it for a case study facility. The validation result showed that the guideline works correctly for both high and low traffic demand.

The Triple Product Rule is Incorrect

The triple product rule, also known as the cyclic chain rule, cyclic relation, cyclical rule or Euler's chain rule, relates the partial derivatives of three interdependent variables, and often finds application in thermodynamics. It is shown here that its derivation is wrong, and that this rule is not correct; hence, the Mayer's relation and the heat capacity ratio, which describe the difference between isobaric and isochoric heat capacities, are also untrue. Also, the relationship linking thermal expansion and isothermal compressibility is wrong. These results are confirmed by many experiments and by the previous theoretical findings of the author.

The Triple Product Rule is Incorrect

The triple product rule, also known as the cyclic chain rule, cyclic relation, cyclical rule or Euler’s chain rule, relates the partial derivatives of three interdependent variables, and often finds application in thermodynamics. It is shown here that its derivation is wrong, and that this rule is not correct; hence, the Mayer’s relation and the heat capacity ratio, which describe the difference between isobaric and isochoric heat capacities, are also untrue. Also, the relationship linking thermal expansion and isothermal compressibility is wrong. These results are confirmed by many experiments and by the previous theoretical findings of the author.

Optimization of the Ultimate Bearing Capacity of Reinforced Soft Soils through the Concept of the Critical Length of Stone Columns

The objective of this paper is to develop an analytical equation based on the concept of the critical-length of columns in order to optimize the ultimate bearing-capacity of soft soils, supporting a strip footing and reinforced by a group of floating stone columns. Optimization procedure was performed on three-dimensional numerical models simulated on the Flac3D computer code, for various soft-soils with different undrained-cohesions (Cu=15–35kPa), reinforced by columns of varying lengths (L) and area replacement ratio (As=10-40%), considering different footing widths B. Obtained results indicate that the optimal bearing-capacity ratio (Ultimate bearing-capacity of reinforced soil/unreinforced soil) is reached for the column critical-length ratio (Lc/B) and increase with increase of the later ratio, depending on As and Cu. Analysis of results also showed that the optimal values of the bearing-capacity ratio in the reinforced soils remain bounded between the lower and higher values (1.28-2.32), respectively for minimal and maximal values of the critical-length ratio (1.1) and (4.4). Based on these results, a useful analytical equation is proposed by the authors, for the expression of the critical-length; thus ensuring an optimal pre-dimensioning of the stone columns. The proposed equation was compared with the data available in the literature and showed good agreement. Doi: 10.28991/cej-2021-03091737 Full Text: PDF