Schedule compression using the direct stiffness method

1993 ◽  
Vol 20 (1) ◽  
pp. 65-72 ◽  
Author(s):  
Osama Moselhi
Keyword(s):  
Structural Analysis ◽  
Critical Path ◽  
Cost Optimization ◽  
Computational Effort ◽  
Trade Off ◽  
Schedule Compression ◽  
Stiffness Method ◽  
Direct Stiffness ◽  
Equivalent Structure ◽  
The Impact

This paper presents a new method for critical path (CPM) scheduling that optimizes project duration in order to minimize the project total cost. In addition, the method could be used to produce constrained schedules that accommodate contractual completion dates of projects and their milestones. The proposed method is based on the well-known "direct stiffness method" for structural analysis. The method establishes a complete analogy between the structural analysis problem with imposed support settlement and that of project scheduling with imposed target completion date. The project CPM network is replaced by an equivalent structure. The equivalence conditions are established such that when the equivalent structure is compressed by an imposed displacement equal to the schedule compression, the sum of all member forces represents the additional cost required to achieve such compression. To enable a comparison with the currently used methods, an example application from the literature is analyzed using the proposed method. The results are in close agreement with those obtained using current techniques. In addition, the proposed method has some interesting features: (i) it is flexible, providing a trade-off between required accuracy and computational effort, (ii) it is capable of providing solutions to CPM networks where dynamic programming may not be directly applicable, and (iii) it could be extended to treat other problems including the impact of delays and disruptions on schedule and budget of construction projects. Key words: construction scheduling, time–cost trade-off, project cost optimization, scheduling with constraints, project acceleration.

Structural Analysis of an Arteriole by the Direct Stiffness Method

1966 ◽  
Vol 88 (4) ◽  
pp. 363-368 ◽  
Author(s):  
G. F. Gerstenkorn ◽  
A. S. Kobayashi ◽  
C. A. Wiederhielm ◽  
R. F. Rushmer
Keyword(s):  
Structural Analysis ◽  
Cross Section ◽  
Piecewise Linear ◽  
Structural Response ◽  
Polar Coordinates ◽  
Heterogeneous Structure ◽  
Time Data ◽  
Stiffness Method ◽  
Direct Stiffness ◽  
The Cross

The direct stiffness method is used to analyze the structural response of the cross section of an arteriole which is both heterogeneous and nonlinear in terms of structural response. A typical segment of the cross section is represented by an assembly of triangular elements. The stiffness matrix and strain-displacement relationships are then derived in terms of polar coordinates for a triangular plate element. Viscoelasticity is included in this structural analysis by using a piecewise linear approach. Stress-time and displacement-time data are presented for two typical cross sections of the arteriole. These results reveal special properties of a heterogeneous structure which is undergoing viscoelastic deformations.

STUDI ANALISIS BIAYA DAN WAKTU MENGGUNAKAN METODE TIME COST TRADE OFF (TCTO) PADA PROYEK TELKOM MANYAR-SURABAYA.

EXTRAPOLASI ◽  
2021 ◽  
Vol 17 (1) ◽  
pp. 20-29
Author(s):  
Rizal Rosyid ◽  
Gede Sarya ◽  
Michella Beatrix ◽  
Wateno Oetomo
Keyword(s):  
Critical Path ◽  
Working Hours ◽  
Time Cost ◽  
Time Duration ◽  
Project Cost ◽  
Trade Off ◽  
Project Duration ◽  
Network Diagram ◽  
Schedule Compression ◽  
Normal Duration

AbstractTime cost trade off is a schedule compression to get projects that are more profitable in terms of time (duration), costs, and income. The aim is to compress the project to an acceptable duration and minimize the total project cost. The reduction in project duration is done by selecting certain activities. The analysis begins by preparing a network diagram (network diagram) using Microsoft Project. After that the crashing process is done using the addition of workers and additional hours of work contained in the critical path. Next do the calculations with the time cost trade off method to find the value of the crash cost and cost slope contained in the critical path. From the results of the analysis, the normal duration of the project is 639 calendar days after the process of crashing, adding work hours to 622 days and labor to 623 calendar days and the initial project cost of Rp. 250,320,084,731 after the process of crashing activities with an alternative addition to labor obtained a fee of Rp. 250,559,140,422 and additional working hours in the amount of Rp. 252,734,398,495. So that it can be concluded with the time cost trade off method there is a reduction in the duration and increase in costs.AbstrakTime cost trade off merupakan kompresi jadwal untuk mendapatkan proyek yang lebih menguntungkan dari segi waktu (durasi), biaya, dan pendapatan. Tujuannya adalah memampatkan proyek dengan durasi yang dapat diterima dan meminimalisasi biaya total proyek. Pengurangan durasi proyek dilakukan dengan memilih aktivitas tertentu. Analisa dimulai dengan melakukan penyusunan jaringan kerja ( network diagram ) dengan menggunakan microsoft project. Setelah itu dilakukan proses crashing menggunakan penambahan pekerja dan penambahan jam kerja yang terdapat pada jalur kritis. Selanjutnya melakukan perhitungan dengan metode time cost trade off untuk mencari nilai crash cost dan cost slope yang terdapat pada jalur kritis. Dari hasil analisa yang dilakukan diperoleh durasi proyek normal 639 hari kalender setelah dilakukan proses crashing kegiatan penambahan jam kerja menjadi 622 Hari dan tenaga kerja menjadi 623 hari kalender dan biaya proyek awal sebesar Rp. 250.320.084.731 setelah dilakukan proses crashing kegiatan dengan alternatif penambahan tenaga kerja diperoleh biaya sebesar Rp. 250.559.140.422 dan penambahan jam kerja sebesar Rp. 252,734,398,495. Sehingga dapat disimpulkan dengan metode time cost trade off terjadi pengurangan durasi dan peningkatan biaya. 

Geometrically Nonlinear Structural Analysis by Direct Stiffness Method

1971 ◽  
Vol 97 (9) ◽  
pp. 2299-2314 ◽  
Author(s):  
James A. Stricklin ◽  
Walter E. Haisler ◽  
Walter A. Von Riesemann
Keyword(s):  
Structural Analysis ◽  
Geometrically Nonlinear ◽  
Nonlinear Structural Analysis ◽  
Nonlinear Structural ◽  
Stiffness Method ◽  
Direct Stiffness

Optimal Design of Grillage Structures with Steel Crossed Beams using Genetic Algorithms

2018 ◽  
Vol 6 (3) ◽  
pp. 1-6
Author(s):  
Ersilio Tushaj ◽  
Niko Lako ◽  
Fatjon Saliu
Keyword(s):  
Genetic Algorithm ◽  
Genetic Algorithms ◽  
Structural Analysis ◽  
Structural Design ◽  
Steel Structures ◽  
Stiffness Method ◽  
Eurocode 3 ◽  
Crossed Beams ◽  
Direct Stiffness ◽  
Algorithmic Approaches

The optimal problem in the structural design is an important issue in the engineering design. Various authors have analyzed the optimization of steel structures using algorithmic approaches. These techniques are generally grouped in deterministic or meta-heuristic techniques. From the introduction of structural optimization in the 1960’ up to now, various methods have been proposed. A genetic algorithm, is built and applied in this study using MatLab soft R2017a to a crossed beams system. The structural analysis is done with the direct stiffness method with constraints verification based on EuroCode 3:2005 criteria. Results are reported in the study.

Application of Finite Element Methods to Lubrication: An Engineering Approach

1972 ◽  
Vol 94 (4) ◽  
pp. 313-323 ◽  
Author(s):  
J. F. Booker ◽  
K. H. Huebner
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Structural Analysis ◽  
Finite Element Methods ◽  
Lubricant Film ◽  
The Finite Element Method ◽  
Engineering Approach ◽  
Stiffness Method ◽  
Direct Stiffness ◽  
System Properties

The finite element method of lubrication analysis is presented for the novice from a viewpoint closely analogous to that of the familiar direct stiffness method of structural analysis. The lubricant film is seen as a system of component elements interconnected at nodal points where flows are summed and pressures (but not necessarily thicknesses, viscosities, or densities) are equated. System properties are deduced from component properties and connections. Detailed equations needed for solution of practical problems are given in Appendices and their use is illustrated in Examples.

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