New Fatigue Screening Criteria for the Fitness-for-Service Assessment of In-Service Process Piping Vibrations

Commonly used piping vibration screening limits are typically justified by experience and lack a well-documented technical basis. This paper presents technical background for future Level 1 Fitness-for-Service (FFS) vibration screening criteria. The criteria assess the risk of fatigue in process piping due to bending mode type vibrations. Finite element analysis (FEA) of 20,000 randomly generated candidate-piping models and high-cycle welded joint fatigue curves for both constant amplitude and variable amplitude loading form the stress limits and basis for the proposed criteria. Most importantly, the proposed criteria aligns with historically used allowable vibration limits rooted in substantial experience. The allowable stress basis implemented in this paper considers periodic and random vibrations making it applicable to situations of mechanically induced, two-phase flow induced, turbulent-induced vibration of single-phase process fluid, or wind-induced, which may be manifested as either periodic or random. To reduce conservatism, limits are set for butt-welded and non-butt welded mainline piping to prevent use of a single blanket limit that may lead to unnecessary piping support alterations/additions, or costly piping configuration changes and unit downtime. Furthermore, the proposed Level 1-type criteria are consistent with previously proposed FFS Level 2 and 3 piping vibration fatigue evaluations [1] intended for inclusion in the ASME FFS-1/API 579 (API 579) Fitness for Service Standard [2].

ANSYS-Based Study in the New Composite Beam for Effective Flange Width

Effective flange width’s value of U-section steel-encased concrete composite beam was studied by ANSYS. Based on the static equivalent principle, the general rules of effective flange width changed with load are summarized by finite element analysis and considering the effect of 4 factors: width-span ratio, loading form, concrete thickness, and material strength including concrete strength and steel strength. The analysis results show that wide-span ratio and load form has a greater impact on the effective flange width; concrete thickness and material strength’s effects can be negligible.

Analysis of Building Technology on WANGYUE Pavilion of Golden Phoenix Temple

The Pavilion structure, as a perfect blend of beauty, practicability and flexibility, is widely adopted in Chinese classical gardens. Besides, pavilions about which a plenty of poems and tales have been made are so delicate, mysterious and gorgeous that they are usually very ideal places for recreation. Focusing on the renowned WANGYUE Pavilion of Golden Phoenix Temple, this paper aims at studying the construction technologies on double-eaves pavilions of timber structure used in Qing dynasty, by means of site survey and other investigating approaches. According to the investigation, the typical and traditional construction technology in south China on double-eaves pavilions was adopted, and the octagonal pavilion with double eaves and pyramidal roof was completed mainly using three beam-erection approaches such as the method of corner beam in the horizontal direction, the method of girder and the method of lever. This pavilion, as a representative structure with reasonable loading form, is constructed in good agreement with local culture and environment, which can provide certain valuable references for the design and construction of antique pavilions nowadays.

Effect of Different Input Loading Form on Structure-Born Sound Radiation

The exciting force’s accurate measurement of is crucial to the structure-born sound radiation. Forced vibration and sound radiation of the ribbed cylinder is examined in the anechoic room. An approach called added mass and damping method is proposed to calculate the elastic vibration and acoustic field of the cylinder. Results obtained from simulation are show to be in good agreement with the experimental data. Sound radiation induced by different input loading form is examined via simulation and experiment. And the equipollence of force and pressure acting on the base is validated.

Uniqueness of steady state and liquefaction potential

A given sand is presumed to have a unique steady-state line. The proximity of an initial state to the steady-state line is considered to be a measure of liquefaction potential. This line of reasoning and application in practice is based on data obtained predominantly from triaxial tests in compression-mode loading. In such tests, relative orientations of bedding plane and principal stress directions remain fixed while stress states along actual failure surfaces may range from active to passive. This study examines the uniqueness of the steady state relative to the mode of loading, form of consolidation, and initial anisotropy as induced by bedding orientation. A sample-preparation method was developed to form triaxial samples with different bedding orientations. Steady states of a uniform sand reached under compressional and extensional modes of triaxial undrained loading of samples with different bedding orientation are compared. Effects of isotropic and anisotropic consolidation are examined. The results indicate the steady-state line obtained for compression-mode loading is different from and does not apply for extension-mode loading. Use of a compression side steady-state line for extension-mode failure states would result in overestimation of steady-state strengths and unconservative stability evaluations. Key words : anisotropy, compression, extension, liquefaction, sand, steady state, triaxial.