Innovative Look at the ‘General Method’ of Assessing Buckling Resistance of Steel Structures

Stability checking is an essential element of the dimensioning of steel frame structures. One of the stability checking methods allowed by EN 1993-1-1 is the so-called general method of assessing structural stability, based on buckling curves and relative structure slenderness λ ¯ op {\bar \lambda _{op}} usually determined through numerical analyses. But this method is not widely used because of the limited computing capabilities of the engineering programs dedicated to static load analyses and difficulties in interpreting the results of the computations. The commonly used computer programs enable one to determine the shape of buckling and critical load amplifier αcr , from which one cannot directly determine the risk of buckling of a real structure. This paper presents a modified and innovative approach to the general method of assessing structural stability, which uses only three parameters, that is, the type of cross section, cross-section strength utilisation and αcr , to determine a member’s/structure’s bearing capacity mobilisation from the stability condition. The problem solution is presented in the form of simple formulas and legible diagrams. Finally, synthetic conclusions are formulated.

Collapse of public buildings, stability checks and the roles of facility managers in Ghana

PurposeThe study investigated the perceived causes of structural failure of public buildings, frequency of stability checks, stability checking procedures, measures to enhance public building stability checks and the roles of facility managers in the Accra Metropolis of Ghana.Design/methodology/approachFollowing a comprehensive literature review, the study employed a structured questionnaire survey and gathered the opinions of sixty-seven facility managers on the facility management practices. Following statistical pretesting of the dataset for reliability, distribution and agreement among the responses, the study analysed the dataset using mean scoring and weighted analysis.FindingsThe analysis showed that external building inspectors rarely inspect stability checks of the studied public buildings in Accra. It is also found that both reactive and proactive stability checking protocols are implemented in public buildings in Accra, but inadequate knowledge of facility managers limits technical stability checks. The study further revealed that stability checks of public buildings can be enhanced through incorporating site and location conditions into the design early upfront, active engagement of facility managers in the design and construction of public buildings, adequate budgetary provisioning for planned maintenance of public buildings, and encouraging appropriate use of public buildings.Originality/valueThis paper, to the best of the authors' knowledge, represents the first attempt to comprehensively examine the causes of structural failure of public buildings, frequency of stability checks, stability checking procedures, measures to enhance public building stability checks and the roles of facility managers in Ghana, from the perspective facility management.

Analysis of Design and Calculation of Wall Protection for Railway Cable Well Construction

The design and calculation of prefabricated assembled reinforced concrete wall protection of cable well plays an important role in ensuring the smooth construction works of railway cable wells. In this paper, taking Ningqi railway route cable well as an example, the design and inspection of prefabricated reinforced concrete wall protection of railway cable wells are analyzed. The calculation includes strength checking and stability checking. Through those checking’s the prefabricated assembled reinforced concrete wall protection of cable well is ensured to meet the requirements of engineering and mechanical performance. The research results also provide some reference and guidance to similar railway cable wells engineering.

The Research on Loose Body Landslide Stability and Treatment

The formation of a loose engineering landslide is carried on, and the comprehensive analysis on the formation mechanism of landslide is studied. The stability checking is carried out. Accordingly, the treatments are put forward.

Determining the Effective Length of Frame Column in the Action of the Fore with Variable Directions

Steel structure is designed by limiting condition generally. Checking its stability is important in design. Calculating the effective length of the column is a key of stability checking. Some charts and formulas are written on Code for Design of Steel Structures, which is not applicable to the structural systems because of some assumptions. What is more, finding some values is not easy and the trend of the values is not obvious. In the paper the effective length of the column in the action of the fore with variable directions is derived by the equilibrium condition method and the effective length of the column chart is also drawn. Using these charts can quickly determine the effective length, and there is an intuitive tendency which the effective length varies with parameters.

Hybrid Stability Checking Method for Synchronization of Chaotic Fractional-Order Systems

A hybrid stability checking method is proposed to verify the establishment of synchronization between two hyperchaotic systems. During the design stage of a synchronization scheme for chaotic fractional-order systems, a problem is sometimes encountered. In order to ensure the stability of the error signal between two fractional-order systems, the arguments of all eigenvalues of the Jacobian matrix of the erroneous system should be within a region defined in Matignon’s theorem. Sometimes, the arguments depend on the state variables of the driving system, which makes it difficult to prove the stability. We propose a new and efficient hybrid method to verify the stability in this situation. The passivity-based control scheme for synchronization of two hyperchaotic fractional-order Chen-Lee systems is provided as an example. Theoretical analysis of the proposed method is validated by numerical simulation in time domain and examined in frequency domain via electronic circuits.

The Practical Calculation Charts to Determine Column Effective Length of Framework and Bent Framework

Calculation of effective length of columns is key of stability checking in design, therefore some formulas and tables are given in Code for Design of Steel Structures (GB 50017-2010), which show some application Limitations. These formulas and tables are made based on assumptions for regular frames. For some special cases, such as existence of the large difference of the column axial force or column length among the framework columns, these formulas and tables are no longer applicable. The practical calculation charts are derived by authors by using the displacement method with the second-order theory, which can be used to quickly determine column effective length and show intuitive trends of the lengths.

Safety Assessment on Retaining and Protecting of Deep Foundation Excavation Adjacent to the Existing Railway

Mizhuo highway overpass crosses Jingha railway. Deep foundation excavation can cause the neighboring structure safety factor drops. To ensure the stability of the Jingha railway embankment, retaining and protecting of deep foundation excavation was set up around the foundation pit. The incremental calculation method was used to analyze the stress deformation of retaining pile and surface settlement near the deep foundation pit. The overall stability checking and anti-overturning stability checking of deep foundation excavation meet the specification requirements. The maximum horizontal displacement of retaining pile is 6.0 mm and 6.6 mm respectively. Surface settlement can not impact the existing railway embankment. In construction practice the retaining pile can be able to effectively ensure the safety of the neighboring structure and to reduce the probability of accidents.