Adhesion and Adhesives Edited by Dr. R. Houwink and Dr. G. Salomon. Vol. 1: Adhesives. Second, completely revised edition. Pp. xvi + 548. (Amsterdam, London and New York: Elsevier Publishing Company, 1965.) 135s.

/pdf/adhesion-and-adhesives-1r2k52nrht.pdf

Adhesion and Adhesives

COMMITTEE MANDATE Concern for crack initiation and growth under cyclic loading as well as unstable crack propagation and tearing in ship and offshore structures. Due attention shall be paid to practical application and statistical description of fracture control methods in design, fabrication and service. Consideration is to be given to the suitability and uncertainty of physical models. The work shall be coordinated with that of Committee V.2.

Fatigue and Fracture

This report contains the findings of a study on fatigue resistance of cantilevered signal, sign, and light supports. Recommended specifications for the fatigue-resistant design of these structures are included. The contents of this report will be of immediate interest to bridge and structural engineers, traffic engineers, and manufacturers. The research determined that, for a typical sign or signal support structure, galloping is the primary cause of vibrations that may result in fatigue damage. It was also determined that the number of structures observed to be galloping in field applications is low. Much variation in the detailing of connections was found, and several details of low fatigue resistance are in use. The research suggests that, through changes in the recommended design wind loads used for design of these structures and avoidance of fatigue-susceptible details, the probability of failure of these structures may be reduced. In addition, the research suggests that mitigation of wind-induced vibrations of structures, once they are observed in the field, may also be a desirable action. The report recommends additional research in this area and provides guidance that designers may consider pending any formal changes to design specifications by the American Association of State Highway and Transportation Officials.

Fatigue-resistant design of cantilevered signal, sign, and light supports

Fatigue analysis and life prediction of bridges with structural health monitoring data — Part II: application

SUMMARY: This paper investigates the effect of the composite action on the seismic performance of steel special moment frames (SMFs) through collapse. A rational approach is first proposed to model the hysteretic behavior of fully restrained composite beam-to-column connections, with reduced beam sections. Using the proposed modeling recommendations, a system-level analytical study is performed on archetype steel buildings that utilize perimeter steel SMFs, with different heights, designed in the West-Coast of the USA. It is shown that in average, the composite action may enhance the seismic performance of steel SMFs. However, bottom story collapse mechanisms may be triggered leading to rapid deterioration of the global strength of steel SMFs. Because of composite action, excessive panel zone shear distortion is also observed in interior joints of steel SMFs designed with strong-column/weak-beam ratios larger than 1.0. It is demonstrated that when steel SMFs are designed with strong-column/weak-beam ratios larger than 1.5, (i) bottom story collapse mechanisms are typically avoided; (ii) a tolerable probability of collapse is achieved in a return period of 50years; and (iii) controlled panel zone yielding is achieved while reducing the required number of welded doubler plates in interior beam-to-column joints. © 2014 John Wiley & Sons, Ltd.

Modeling of the composite action in fully restrained beam‐to‐column connections: implications in the seismic design and collapse capacity of steel special moment frames

T-joint specimens were tested in tension to investigate the ductility and strength requirements for the base metal; particularly with heavy section wide-flange columns as the transverse member loaded in the through-thickness direction. The column sections were obtained over a range of years from four steel mills (integrated and electric furnace) under four different ASTM specifications. Sulfur levels ranged from 0.003 to 0.043% and carbon from 0.05 to 0.15%. The through-thickness strength of the column flanges exceeded 690 MPa, well above any possible demand that could come from ordinary structural steel. Because there is no yielding of the column flanges in the through-thickness direction, the lower ductility in this direction should not be a concern, even if the sulfur levels are at the upper limits of the ASTM A992 specification.

Ductility and Strength Requirements for Base Metal in Welded T-Joints

This report describes research which focused on determining equivalent static pressures for fatigue loads on cantilevered highway sign support structures. A cantilevered variable message sign (VMS) instrumented with strain gages, pressure transducers, and a wind sentry, was continuously monitored for three months. Short-term testing was conducted on the structure in order to determine the dynamic characteristics such as stiffness, natural frequency, and percent of critical damping. Long-term monitoring was performed to capture the structure's response to natural wind gusts, galloping, and truck-induced wind gusts. This data would the be applicable towards determining appropriate fatigue design wind loads for future sign support structures. Contents: v. 1. Fatigue related wind loads on highway support structures / by Kevin W. John, Robert J. Dexter -- v. 2. Fatigue testing and failure analysis of aluminum luminaire support structures / by Kevin W. Johns, Robert J. Dexter

Fatigue performance of variable message sign & luminaire support structures

The propagation and stability of very long fatigue cracks in a redundant stiffened-panel structure is considered. Cracks have propagated in ships to a length greater than 8.0 m without sudden fracture or instability. To investigate this phenomenon, large box beams were fatigue tested in four-point bending. The crack was started in a wide stiffened panel that comprised the tension flange. The stiffened panels, fabricated from relatively thin A572 Grade 50 plate (less than 26 mm thick), were expected to have a ductile fracture mode. These panels did not fracture at service stress levels despite cracks greater than one meter in length.

Propagation and Fracture Behavior of Large Cracks in Redundant Structures

Large cellular box beams, 8000 mm long, were fatigue tested in four-point bending. A total of ten tests were performed in a test matrix which included several variations in load ratio. The nominal stress range varied from89 to 219 MPa. The box beams were fabricated from HSLA-80 steel. Crack growth rates in the base metal were obtained from CT specimens of various heats, orientations and thicknesses. In every test, a through-thickness crack developed at an intentionally poor weld detail after less than 30% of the total fatigue life. Nearly fixed crack growth rates were observed for a region of cracking, due to web restraints, redundancy aspects of the box beam design, and welding residual stresses. Cracks 1500 mm or more in total length still grew in a stable manner. The observed crack growth rates were related to macroscopic beach marking of the fatigue crack surface as well as microscopic striations. Correlation of the observed crack growth rates to the square of stress range was relatively good. The cracking history is decomposed into four separate stages. Using the concept of effective stress intensity factor range, crack growth rates predictions for each stage are presented.

Propagation of Very Long Fatigue Cracks in a Cellular Box Beam

Recent research has given more accurate fatigue design loads for truck-induced wind loads on cantilevered highway sign support structures. This research consisted of short and long-term field testing on a variable message sign over an interstate highway. The results of the research indicated that a worst case truck-induced wind load of 1760 Pa with a reduction dependant upon the height above the road results in an adequate fatigue design load.

Robert J. Dexter

Papers

Ductility and Strength Requirements for Base Metal in Welded T-Joints

Fatigue performance of variable message sign & luminaire support structures

Propagation and Fracture Behavior of Large Cracks in Redundant Structures

Propagation of Very Long Fatigue Cracks in a Cellular Box Beam

Truck-induced wind loads on highway sign support structures