EXPERIMENTAL REPORT ON GLASS PANELS AGAINST STATIC AND REPEATED IN-PLANE COMPRESSION LOADING

Investigation on allowable compressive stresses in pretensioned concrete members at transfer

Building codes generally specify maximum allowable compressive stresses for basic pile materials that control the structural design of piles. Sometimes these prescriptive type provisions are qualified by performance type provisions that permit such allowable stresses to be exceeded under controlled conditions. Combined prescriptive and performance regulations governing pile foundation design and installation is recommended because totally prescriptive or totally performance type provisions are impractical under the present state of the art. A relatively high structural factor of safety must be reflected in allowable stresses for pile material to provide for the many uncertainties currently existing in pile foundation design and installation and the several conditions under which the actual structural factor of safety can be less than assumed. Until we have more precise answers to all of our problems in designing and installing satisfactory pile foundations, any move to reduce the structural factors of safety below current levels would be ill advised. An examination of the current allowable stresses and proposed increases indicates that under today's state of the art, a practical limit has been reached or in some cases exceeded and proposed increases are generally unwarranted or undesirable.

Simplified strength design method for allowable compressive stresses in pretensioned concrete members at transfer

One of the main reasons for setting permissible stresses in prestressed concrete flexural members is to insure that serviceability criteria are met. However, the allowable compressive stress at service seems to be unjustified. The issue of allowable compressive stress has not been emphasized in the past, since it seldom controlled in design. But now the compressive stress limit has become a critical factor and more restrictive in modern designs, such as spliced girder bridges, long-span beams in office buildings, and segmental box girders. This paper discusses the proposed ACI 318-95 Building Code and AASHTO Bridge Specifications allowable compressive stress changes. It is suggested that the ACI allowable compressive stress be 0.60 f' c due to load combinations of transient nature, plus the corresponding prestress forces, and 0.45 f' c due to effective prestress plus permanent (dead) loads. The reasons for the proposed changes and several examples are presented. It is shown that these changes do not adversely affect the acceptable safety margin against compression failure or deflection and fatigue limits

The objective of this paper is to use probabilistic methods to assess the safety level of unreinforced masonry panel walls subjected to out-of-plane wind loads designed according to the MSJC and IBC codes. Data from 327 full-scale tests are examined to develop statistics on the flexural bond strength of the masonry. A lognormal distribution with a coefficient of variation of 0.50 was prescribed for the flexural tension strength. Reliability analyses indicated that the safety level against flexural tension failure is consistent with that inherent in construction with other materials subjected to wind loading, even with using a one-third increase in allowable stress. However, the level of safety was not uniform with different types of masonry construction. Using an allowable stress of 25% of the mean ultimate flexural tension stress from full-scale tests results in a safety level that is consistent with current design. Therefore, it is concluded that the one-third stress increase for unreinforced masonry in flexural tension under wind loads is justified. Empirical observations also bear out the adequate safety level of structures designed with the one-third stress increase; there has not been an undue amount of failures. Since the IBC has prohibited the use of the one-third stress increase, it is proposed that the allowable flexural tension stresses in the MSJC code be increased by one-third to compensate for this.

Estimation of bearing capacity and settlement plays an essential role in designing pile foundations of buildings. This paper presents the results of pile static and dynamic loading tests taken place in the construction sites of Caspian Sea Port Prorva and Tengiz. The static loading tests (SLT) and static compression loading tests (SCLT) were carried out according to the Kazakhstan GOST and ASTM standards correspondingly. The dynamic loading tests (DLT) were performed by GOST, as well as by pile dynamic analyzer (PDA) in accordance with ASTM standards. According to the results of DLT of driven joint piles (with a cross-section of 40×40 cm, lengths of 25 m and 27 m) performed by PDA, the bearing capacity of the piles was 2143 kN. In the construction site of Prorva, the bearing capacities of driven joint piles according to the results of SCLT were2067 kN and 2042 kN. In the construction site of Tengiz, the bearing capacities of driven piles tested by SLT were 1000 kN and 1605kN. These investigations are important for the understanding of soil-structure interaction, especially of driven piles with a cross-section of 40x40 cm and lengths of 12 and 16m in construction site Tengiz.

This report has been developed to provide more specific loading recommendations for steel transmission towers. Other features include design formulas for compression members, fabrication and testing recommendations, foundation nomenclature, survey information, and construction methods. The development of workable and tested compression formulas for angles based on the yield point of steel receives considerable attention. Compression formulas illustrated by curves are developed for both 36,000-psi and 50,000-psi yield steels. Examples are included showing slenderness ratio determination and allowable compressive stress for angles based on yield point. Angle width to thickness ratio is recognized in the development of the formulas. The effects of end connections is recognized in determining the slenderness ratio.

The Chin's plot method is the most widely used method in Singapore to assess the ultimate skin friction and ending bearing separately based on static pile load test results. In this study, a large number of pile load tests for driven piles were back analyzed using the Chin's plot method. The obtained data were examined in order to evaluate the appropriate design ranges for skin friction coefficient, Ks and end bearing coefficient Kb, which are the two key parameters for pile capacity estimation in design. It was revealed that, generally, the currently adopted design ranges were over-conservative for displacement piles. New design ranges and limits for Ks, Kb and unit end bearing, qb, were suggested, and their typical values for conventional designs were recommended. Further, the importance of pile load test in the design of piling foundation was emphasized. Whenever practicable the ultimate pile bearing capacity should be obtained from pile load tests, and all indirect estimations of pile capacity should be evaluated against the static load test results.

Glass curtain walls consist of large glass panes typically supported by vertical and horizontal framing elements. Wind forces on the curtain walls are transmitted to the building frame at the floor levels, most often by the vertical framing. The glazing transmits the wind forces to the framing and also acts to restrain lateral-torsional motion of the framing. The horizontal members between mullions also may restrain lateral-torsional buckling of the mullions. This paper is concerned with the lateral buckling strength of the long slender framing elements and the design of such members. Since there is practically no literature on this subject, some designers make very conservative assumptions. For example, the paper illustrates that neglecting the bracing offered by structural glazing, even on the tension flange side of a member, can be very inefficient. Analyses are given herein for several different supporting conditions that approximate minimum and maximum bracing and a realistic approximation to the restraint afforded by structurally glazed elements. For a typical application, comparisons are made of the allowable compressive stress given by current design procedures with corresponding values derived from different theoretical analyses. These comparisons show the great influence of the restraint that may be offered by the structurally glazed elements. Large increases in the allowable compressive stresses are possible. A method that experimentally provides verification of stability is presented, and several tests of such designs are discussed. The significance of the conclusion generates a design/analysis method that more fully harnesses the multi-function capabilities of structurally glazed curtain wall framing. This will enable the designer, manufacturer, and contractor to provide a more efficient system that will thus have an edge in competition with other exterior wall products in the building construction industry.

This paper employs a simplified analytical method to investigate the influence of reaction piles on the load–displacement behaviour of a test pile in static load testing. A parametric study is conducted to examine the effects of factors such as pile spacing ratio, pile slenderness ratio, and pile soil stiffness ratio. Several soil profiles are considered in the study. The parametric study also includes the cases of static load testing in the lateral direction. The correction factors for the initial pile head stiffness obtained from static pile load tests with the use of reaction piles are given in charts. Furthermore, analyses of centrifuge modelling of axially loaded piles are carried out using the simplified analytical method. Good agreements between the test results and the analysis results are demonstrated, and the applicability of the correction factors is verified.Key words: reaction piles, interaction, initial pile head stiffness, static vertical load testing, static lateral load testing, simplified analytical method.

A rotational energy harvester utilizing an asymmetrically deformed piezoelectric transducer subjected only to unidirectional compressive stress

Reliability-based evaluation of load carrying capacity for a composite box girder bridge

This paper intends to obtain the reference data in order to make better column formulas, considering the scatter of buckling load in compressive members. In consideration of the scatter of the buckling load, we investigate the effect of random initial imperfections, which are random residual stress, random yield stress and random initial deflection thought most important, with probabilistic methods. In the first, the probability distribution of buckling loads about weak axis for rolled H-section members are made with the Monte-Carlo simulation procedure mainly. Next, we statistically deal with the result of the simulation and obtain the probability distribution function, mean value, standard deviation and coefficient of variation of the buckling load. And we considered them carefully. After all, some properties connected with the variation of buckling load in compressive members are represented definitely. Furthermore, reffering to the allowable compressive stress in Steel Structural Design Specification (A. I. J.), we point out that the factor of safety in column formula is doubtful about critical slenderness ratio.

Pilesr are both statically and dynami cally tried to acquire the limit and to check outline. The two sorts will give comes about that may differ in light of the technique utilized as a part of leading the test. It is thusly, important to think about the aftereffects of a static load test with dynamic load test. Numerous comparison studies are directed around the world, yet the vast majority of them are for displacement driven pile. In this way, the consequences of the test are looked at for substitution-exhausted piles. The piles are tested statically before dynamic test. The test results show that a not too bad comprehension was expert between both the tests with in addition to less 7mm at design load regarding settlement. Moderately, the settlement foreseen in powerful load test is littler diverged from static load test. Regarding absolute bearing limit, Davisson's technique gives the insignificant outrageous load regard diverged from various strategies. The Davisson's strategy is utilized to analyze the outcomes since it is more moderate. The examination shows that the piles are inside 15% in regard as far as possible traversed Davisson's strategy. Since the static test was coordinated before unique test, the limit got from dynamic test is higher because of the pile experienced flexible pressure amid static load test and furthermore because of soil setup.

Truss structures are widely employed in the industrialized world. They appear as bridges, towers, roof supports, building exoskeletons or high technology light space structures. This paper investigates the simultaneous size, geometry and topology optimization of real life large truss structures using Genetic Algorithms (GAs) as optimizer and Finite Element Method as analyzer. In general the large truss structures are constructed from the duplication of some basic modules called bays. Thus, the final optimum design may be reached by optimizing the characteristics of the basic bays instead of optimizing the whole structure. Both single and multi-objective functions based on the mass of the structure and the maximum nodal displacement, have been considered as the cost functions. In order to have realistic optimal designs, the cross-sectional areas have been extracted from the standard profiles according to AISC codes and practical conditions are imposed to the bays. The design optimization problem is also constrained by the maximum stress, maximum slenderness ratio and the maximum and minimum cross-sectional area of the truss members. To accommodate all these constraints, two different penalty functions are proposed. The first penalty function considers the normalization of violated constraints with respect to the allowable stress or slenderness ratio. The second penalty function is a constant function, which is used to penalize the violations of the slenderness ratio. Two illustrative examples of realistic planar and space truss structures have been optimized to demonstrate the effectiveness of the proposed methodology.