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A half-scale field test was conducted on a pile group installed at a stiff clay site. The pile group consisted of eight steel H-piles, with a battered pile at each corner, and connected to ...

This work examined the behavior of a RC beam on a soil foundation subject to concentrated vertical loads and bending moment in both the elastic and the plastic phases. Some of the simplifie...

In developing a vertical load transfer function for bored piles buried in cohesive intermediate geomaterials (IGM), it is essential to understand the shear behavior of the rough sidewall. ...

The two-layer model previously established by the author is expanded to well capture the response of back-rotated and shape-distorted piles set with P−Δo effect (P is the vertical load on p...

Stone columns are normally used to improve the bearing capacity and reduce the compressibility of soft clayey soil. However, with the application of vertical load, stone columns bulge, and...

Column-supported embankments (CSEs) with or without a load-transfer platform (LTP) can reduce settlements, improve stability, and prevent damage to adjacent facilities when embankments are ...

The vertical load acting on a support structure is affected by the loss of self-bearing capacity of the rock inside the plastic zone. This load can then be accounted for by analytical calcu...

Since the devastating 2011 tornado season, there has been renewed interest in understanding tornado wind loads and developing methodologies to reduce the risk of tornado damage. This study ...

The load deformation and failure behavior of shallow footings can be described in a macroelement formulation. This paper deals with the study of the failure surface and the definition and validation of plastic load deformation by single surface hardening models. The straightforward application of the plasticity theory to the soil-foundation system makes it possible to extend the given expression for the case of unsaturated soils. This paper studies a small-scale footing test on unsaturated sand for the formulation of the elastoplastic macroelement of shallow footings under a centrally applied vertical load. The influence of soil suction on different parameters associated with the macroelement is studied and calibrated against experimental results. The presented model shows good agreement with the experimental results. Finally, the limitations and still open questions of the approach are discussed in detail.

This paper presents a simplified method to predict the thermal and mechanical behavior of a new cold-formed steel floor system at room and elevated temperatures. A four-point bending test of such a floor assembly was performed at room temperature, and an efficient method to estimate the elastic rigidity and strength of the floor system was verified. The temperature progression of the floor section in a fire situation was well predicted based on the implicit finite difference method, taking into account the effects of ceiling materials falling off. A thermal-mechanical model was then developed by simplifying the floor system to a laterally restrained joist subject to constant vertical load and a non-uniform temperature distribution. The time-dependent vertical deflection of the floor joist was well predicted, whereas the response in the final stage of fire exposure was overestimated, probably due to the severe joist degradation and the neglected contribution of the autoclaved lightweight concrete s...

Intermediate diaphragms are used in precast concrete girder bridges for three primary reasons: (1) to prevent torsional girder rotations during girder erection and deck placement operations, (2) to increase vertical load distribution between girders, and (3) to transfer and spread horizontal impact loads from an overheight vehicle to adjacent girders. Significant variation currently exists in intermediate diaphragm specifications between states. The importance of bracing girders after erection and during construction is widely accepted as essential. Although it is clear that intermediate diaphragms have some effect on bridge performance, the benefit is considered by some to be negligible. Increasing numbers of states have adopted permanent steel or temporary intermediate diaphragm alternatives in place of traditional cast-in-place concrete. Wide variations are found between states regarding the configuration, spacing, and transverse alignment of diaphragms. This article presents a detailed survey ...

The installation of foundations and ground improvement systems alters soil stresses affecting their soil-structure interaction and behavior under vertical loading. The installation effects have been investigated for several foundation types, especially for driven piles; however, experimental full-scale investigations of drilled displacement piles are very limited. This paper focuses on investigating the short-term installation effects of controlled modulus columns (CMCs) using an instrumented full-scale field test unit. The soil was instrumented using push-in pressure sensors (PS) and shape acceleration arrays (SAAs) to monitor the evolution of soil horizontal stresses, pore water pressures, and lateral displacements during installation and vertical load test. These sensors were installed at approximately 1D, 2D, 3D, and 4D from the outside surface of the CMC shaft, where D is the diameter of the CMC. The measurements presented in this paper clearly show that the soil experienced an increase of ho...

The load transferring mechanism was investigated and then used to establish the load transferring equation. A calculation method for the vertical load transferring characteristic of the rock socketed pile was proposed to make up for the deficiency of that method in current norms. This method can derive not only the expression of the socketed length of pile, but also the load sharing ratio at the pile tip. Case histories were used to observe the variation of the socketed length and the load sharing ratio at the pile tip over the settlement at the pile top. The results indicate that the required socketed length increases as the settlement requirement at the pile top decreases. The larger the settlement at the pile top, the higher the load sharing ratio at the pile tip. The increment of the socketed length ratio results in the descent of the bearing ratio of the pile tip resistance when other conditions remain unchanged. The method can determine the socketed length of the pile both safely and economi...

Eight building seismic rubber bearings (four uninsulated lead rubber bearings, one insulated lead rubber bearing, two uninsulated natural rubber bearings, and one insulated natural rubber bearing) were experimentally investigated in fire tests following the ISO834 standard heating process. The effects of vertical load and the duration of fire on the failure mode and residual mechanical properties of the rubber bearings were analyzed. The experimental results show that (1) the fire resistance of rubber bearings without insulation fails to exceed 1.5 h; (2) the duration of fire exposure has significant influence on the mechanical-properties degradation of rubber bearings; (3) the effect of vertical load, to which rubber bearings were subjected during the fire, on the residual mechanical properties and fire resistance is inevident; and (4) the proposed insulation is successful in preventing rubber bearings from significant degradation in mechanical properties in fires.

In the United States, an estimated $1 billion is spent annually on repair and replacement of deep foundations. In a recent study, the possibility of using ultrahigh-performance concrete (UHPC) for deep foundation applications was explored with the objectives of increasing the service life of deep foundations supporting bridges to 75 years and reducing maintenance costs. This paper focuses on field evaluation of two UHPC piles and references a steel H-pile. An UHPC pile with an H shape was designed to simplify the process of casting the pile and reduce the volume (i.e., cost) of the material needed to cast the pile. Two instrumented UHPC piles were driven in loess on top of a glacial till clay soil and load tested under vertical and lateral loads. This paper provides a complete set of results for the field investigation conducted on UHPC H-shaped piles. The results presented in this paper prove that the designed UHPC piles can be driven using the same equipment used to drive steel H-piles through hard soil layers without a pile cushion. The vertical load capacity of the UHPC pile was over 80% higher than that of the steel H-piles.

This paper reports on the behavior of simply supported (I-shaped cross section) steel beams prestressed by tendons. It is well known that this typology of beams has successfully been used mainly in the past. Prestressed steel beams are lighter than traditional ones that have the same length and vertical load capacity; this aspect could make them economically advantageous and a viable solution in many practical situations. This paper analyzes prestressed steel beams having a medium span ranging from 35 to 45 m and which are to be used as roof structural elements. This study focuses on two parameters that are considered two of the fundamental items for the design: the number of deviators and the value of the prestressing force. This study has been carried out with nonlinear finite-element analyses that take into account both mechanical and geometrical nonlinearities. In particular, the behavior of these beams has been investigated up to failure during tensioning and during loading (after tensioning). The effect on the structural response of bracing, which can be only at the top flange of the beams or at the top and bottom flanges of the beams, also has been considered.

In this study the vertical push-down analysis was conducted to investigate the resistance of steel moment frames for progressive collapse. The analysis was carried out by gradually increasing the vertical displacement in the location of the removed column and the vertical load in all spans corresponding to the increase of vertical displacement. The analysis results showed that the load resisting capacity increased as the number of stories and the number of spans increased. However, as the length of a span increased, the load resisting capacity against progressive collapse decreased. The load-displacement relationships obtained from push-down analyses were compared with those obtained by incremental nonlinear dynamic analyses, and the results showed that the maximum load factors resulted from the dynamic analyses were a little less than those from the push-down analyses. This implies that the push-down analysis might overestimate the inherent capacity of structures against progressive collapse.

Penetration of skirts is an essential design issue for offshore skirted foundations and anchors in sand. Skirts may not penetrate far enough into dense sand by the available submerged weight alone. It may therefore be necessary to apply underpressure inside the skirt compartment to produce an increased driving force and to reduce the penetration resistance. This paper recommends procedures to calculate penetration resistance and required underpressure for skirts penetrated in dense sand with and without interbedded clay layers. The recommendations are based on interpretation of skirt penetration data from prototypes, field model tests, and laboratory model tests in dense sand. The paper first presents a model to calculate the penetration resistance of skirts penetrated by weight, or other external vertical load that does not cause flow of water in the sand. Two models are considered; one based on bearing capacity equations with friction angles from laboratory tests, and the other one based on empirical correlations with CPT tip resistance. The bearing capacity model gives more consistent correlations with the empirical data than the CPT model. Thereafter, a model to account for the effect of underpressure applied inside the skirt compartment is proposed. This model is developed based on interpretation of available prototype and model test data from skirts penetrated by underpressure. The results show that underpressure facilitates skirt penetration in sand considerably by providing both an additional penetration force and a reduced penetration resistance. It is also shown that interbedded clay layers can prevent flow of water through the sand and eliminate the beneficial reduction in penetration resistance.

The laboratory and field test data on the response of piles under the combined action of vertical and lateral loads is rather limited. The current practice for design of piles is to consider the vertical and lateral loads independent of each other. This paper presents some results from three-dimensional finite-element analyses that show the significant influence of vertical loads on a pile's lateral response. The analyses were performed in both homogeneous clayey soils and homogeneous sandy soils. The results have shown that the influence of vertical loads on the lateral response of piles is to significantly increase the capacity in sandy soils and marginally decrease the capacity in clayey soils. In general, it was found that the effect of vertical loads in sandy soils is significant even for long piles, which are as long as 30 times the pile width, while in the case of clayey soils, the effect is not significant for piles beyond a length of 15 times the width of the pile. The design bending moments in the laterally loaded piles were also found to be dependent on the level of vertical load on the piles. � 2007 ASCE.

Twenty one 2.4 m by 2.4 m ( 8 ft by 8 ft ) wood framed shear walls were tested to study the effect of vertical load and hold-down anchors on the cyclic behavior of the wall. Seven different configurations were investigated including walls without hold-down anchors and uniform vertical loads of 0, 6, 12, and 25 kN∕m (0, 425, 850, and 1,700 lb∕ft ) and walls with hold-down anchors and uniform vertical loads of 0, 12, and 25 kN∕m (0, 850, and 1,700 lb∕ft ). The walls were loaded cyclically according to the Consortium of Universities for Research in Earthquake Engineering test protocol. Results show that the effects of vertical load on the cyclic response of wood frame shear walls are to: (1) increase the lateral stiffness and (2) increase the energy dissipation capacity. The lateral stiffness increased by up to 80% for walls with vertical loads of 25 kN∕m (1,700 lb∕ft) , over the full range of displacement amplitudes; energy dissipation increased by up to 100% for walls with vertical loads of 25 kN∕m (1,700 ...

Full-scale tests were performed on embankments with a beam foundation supported by floating and end-bearing piles. An analytical model based on the soil arching mechanism appeared to be able to predict accurately the vertical load transferred to a group of beams at a small center-to-center distance. However, when the distance between the beams was too wide or the embankment was too low to mobilize soil arching, the vertical load transferred to a beam could be predicted accurately with a model based on the punching shear mechanism. Greater embankment loads could be transferred to a piled beam through soil arching than could be transferred through punching shear. Beams in a piled embankment should be placed sufficiently close to each other to allow application of the soil arching model for design. Embankment loads could be transferred to both floating and end-bearing piles. Although load-transfer behavior was similar, the settlement of floating piles was significantly larger than the settlement of end-bearing piles. Settlement in a piled embankment could be reduced considerably by the application of end-bearing piles with a group of beams at a small center-to-center distance.

A series of 10 tests were conducted to determine the effect of a vertical load on the lateral load capacity of wood frame shear walls. Static tests were performed on 2.4 m-by-2.4 m wood walls, for varying vertical load. Tests were conducted with and without hold-down anchors. Specimens were subjected to three half cycles of lateral loading, the final being to failure. The presence of vertical load on a wood frame shear wall was found to have a significant effect on the lateral load capacity of the wall. The ultimate load capacities of walls with hold-down anchors increased by 20 and 28% for walls with a vertical load of 12 and 25 kN/m, respectively, as compared to the wall without vertical load. The vertical load was also found to have significant effect on the lateral stiffness of the wall. Results also show that hold-down anchors do not add significantly to the strength of the wall when a vertical load equal to the maximum allowable is present. Finally, the results presented suggest that current code specified allowable shear forces are conservative when a vertical load is present; the wall has additional reserve capacity than is reflected by current code specified allowable shears.

This paper focuses on the flexural-torsional buckling and ultimate resistance of parabolic steel arches with box sections subjected to full-span uniformly distributed vertical load by using finite-element numerical analyses. First, analyses on prebuckling internal forces and flexural-torsional buckling loads are performed and compared with the existing theories. They show that parabolic arches under uniformly distributed vertical load are actually subjected to combined axial compressive and in-plane bending actions, rather than pure compression in the classic theory. Because the bending moment is substantial for shallow arches, the classic theory with the assumption of pure compression does not predict exactly the flexural-torsional buckling load. Second, the flexural-torsional ultimate resistance of parabolic arches is explored based on extensive finite-element numerical results, resulting in a design method based on a modified slenderness. The rise-to-span ratio is found to have a great effect o...

In this paper, a finite element analysis (FEA) model of seven span continuous conductors and insulators for an ultra high voltage (UHV) transmission line in a heavy icing area was established for ice shedding analysis. The parameters considered in the ice shedding simulation analysis include damping ratio, ice shedding ratio, ice shedding modes, and ice thickness. The dynamic responses including jumping heights, unbalanced tensions, and vertical loads at the end of the insulator were obtained. The effects of each of the parameters on the dynamic responses were discussed. The design values for unbalanced tensions and vertical loads were proposed for the UHV suspension tower in a heavy icing area based on the analyses results. The dynamic magnification factors of the vertical load should be between 1.06 and 1.11. For the suspension tower in 20 and 30 mm icing areas, the uplift load percentage is proposed to be 10%. For the suspension towers in 40 and 50 mm icing areas, the uplift load percentage is ...

Improved analysis methods and guidelines are presented to simulate the seismic collapse of nonductile concrete frame buildings with masonry infills. The analysis tools include an inelastic dual-strut model that captures the post-peak behavior of the masonry infill and its interaction with the surrounding frame. The dual compression struts capture the column-infill interaction that can cause shear failure of the columns and loss of their vertical load carrying capacity. A rigid softening shear degradation model is implemented in the beam-column elements to capture the shear failure of nonductile RC columns. Guidelines are presented to determine the strut model parameters based on data from 14 experimental tests on infill frames. The models are applied in three-dimensional nonlinear dynamic analyses of a three-story nonductile concrete frame prototype building with infills. The incremental dynamic analyses technique is utilized to understand the effect of the infill-column interaction and the rockin...

Tornadoes are an extremely devastating natural hazard that have significant consequences but are currently not considered in the structural design codes due to their low probability of occurrence. These low-occurrence high-consequence events have been studied but not to the extent of other natural hazards. This paper presents the results of a study whose objective was to provide quantitative insight into a rational design wind speed for tornadoes considering the current state-of-practice in construction methods. Five archetype buildings were selected to be representative of the typical residential structure design space in tornado-prone regions of the United States. Wind analysis was performed using the ASCE standard loading in combination with modification factors for tornadic winds developed from the available literature. Fragilities were developed for the main components along the vertical load path that included roof sheathing and roof-to-wall connection. Then, system fragilities for the combi...

The available closed-form solutions for vertically loaded piles have been, strictly speaking, limited to homogeneous soil, or nonhomogeneous soil with the shear modulus as a power of depth. The latter solutions —based on a zero shear modulus at ground surface—are generally sufficiently accurate for normally consolidated soil. For overconsolidated soil, however, there is generally a nonzero shear modulus at the surface, which may affect pile response. In this note, rigorous closed-form solutions are established to account for the nonhomo- geneity of soil profile with nonzero shear modulus at ground surface. The solutions are developed using a load transfer approach, and are shown to give satisfactory results in comparison with a more rigorous continuum- based numerical approach, when the proposed load transfer factors are adopted.

Flat-ended or wedge-shaped rigid punch problem is considered in this paper. The punch is with one end sliding and the other end with a sharp corner coming into a half-plane. The model of the punch is that the flat-end punch is inclined by an angle e or the wedge-shaped punch with e is pushed vertically. A crack is assumed to be initiated from the end with the corner, and Coulomb's frictional force exists on the contact region. The general solution of the problem is derived in an analytical way, and the relation among the vertical load on the punch, rotating angle of the punch, and the contact length is found. Stress intensity factors of the edge crack are calculated in different cases. The resultant moments at the origin of the coordinates are also calculated, which can be used to decide the position of the vertical force on the punch.

In contrast to design of structures for their service life, very little information is provided to the engineer for selecting appropriate design loads for construction. Before new design loads or load combinations can be recommended or existing recommended values modified, the adequacy of current design loads for construction must be evaluated. This can be accomplished only by comparing actual load data with design loads prescribed by available standards. This paper presents the results of one such study to investigate the adequacy of current construction load provisions in the context of vertical loads on shores during reinforced concrete construction. Construction load provisions from ACI 347, the OSHA standard, ANSI A10.9, and the proposed ASCE construction load standard are first reviewed. Design loads recommended by available standards are evaluated and compared with actual (measured) axial shore loads. Shore load data from six sites are considered, including two recently instrumented projects and four multistory buildings studied previously.

Retaining walls that do not move are customarily designed based on the assumption of at-rest conditions, with no consideration of vertical shear loads applied by the backfill. However, field and laboratory measurements have shown that vertical shear loads do act on nonmoving walls. A simple theory for calculating the magnitude of vertical shear loads on nonmoving walls is presented in this paper, and typical results from the theory are discussed. A companion paper presents the results of finite-element calculations, case history data, and recommendations for retaining wall design.

Massive concrete walls constructed on rock foundations, as well as other nonmoving retaining walls, are customarily designed for at-rest earth pressures. Vertical shear loads applied by the backfill are usually not considered in design of nonmoving walls, even though many field and laboratory measurements have shown that such loads exist. Vertical shear loads can be very beneficial for stability of retaining walls, because they provide restoring moments to counteract overturning moments from lateral earth loads. In this paper, model test results and case history data are reviewed, the results of finite-element calculations are presented, and a simple design procedure is developed. It is shown that significant economies can result from consideration of vertical shear forces in design of nonmoving retaining walls.

Lateral buckling of unbraced wood composite I-joists is a form of instability that causes the joist to deflect laterally and rotate. This instability may be a cause of worker falls and should be explored to understand the range of loading and out-of-plane motion required to cause lateral buckling. While walking on unbraced joists is uncommon on construction sites, understanding the movement of unbraced joists is needed to model more commonly observed partially braced joists. This paper investigated the load and out-of-plane movement of several unbraced wood composite I-joists subjected to human walking loads. Vertical load at the ends of the joist, top and bottom horizontal loads at one end of the joist, as well as lateral deflection and rotation at the midspan and quarter-span were measured while participants traversed the joist. Lateral buckling of joists was observed due to walking loads. Total vertical load measured was similar to participant weight, while horizontal loads ranged from 9.6 to 1...

Past experience has shown that manufactured homes are susceptible to high wind forces. Because of the typical “temporary” nature of their foundation system, the foundation design must provide adequate resistance to prevent overturning of a manufactured home due to lateral loads. A generally accepted system of piers for vertical load support and metal strapping and soil anchors with stabilizer plates for lateral load resistance are typically used as the foundation system. Several organizations and code bodies have specified the lateral load-resistance requirements of the lateral load-resisting tie-down anchors. Tests have shown that anchors typically used to tie down manufactured homes do not achieve the desired resistance. The specified lateral load resistance can be met if there is a proper understanding of the overall behavior of an anchor embedded in a particular soil. This paper reviews the existing standards and discusses the behavior of soil anchors subjected to axial and shear loads.

The influence of four different lateral displacement patterns used for experimental simulation of seismic behavior of masonry walls has been studied. Thirty-two equal reinforced-masonry walls have been tested by imposing monotonically increasing displacements; cyclic lateral displacements with amplitudes, stepwise increasing in predefined blocks of two different shapes and repeated three times at each amplitude peak; and simulated displacement seismic response. By imposing the same displacement pattern dynamically, higher values of lateral resistance and more rigid initial behavior of the walls has been obtained than statically. Higher resistance and larger ultimate displacements have been obtained by monotonic than by cyclic loading procedures of all types. At a higher level of vertical load, lateral resistance of the wall was improved, but deformability and ductility decreased at both, static, and dynamic types of loading at all load patterns.

Results of three-dimensional (3D) finite-element failure analysis of composite masonry walls subjected to both vertical and horizontal loads are presented in this paper. The wall is modeled by using eight-noded solid elements and cracking at the interfaces is defined by a simple Mohr-Coloumb failure criterion. The smeared crack technique is used to model the cracks. It is shown that cracking in the collar joint is initiated at a much smaller magnitude of the horizontal inplane load compared to the vertical load. This phenomenon may be attributed to the relatively high rigidity of the wall in the vertical direction. The failure loads for composite walls are computed using the 3D analysis and are compared with those obtained from an approximate method and experimental values. It is shown that the computed failure loads follow the same trend as the experimental results.

Each year many prestressed-concrete (P/C) girder bridges are damaged by overheight vehicles or vehicles transporting overheight loads. The effects of this type of loading on P/C bridge behavior was investigated for various types and locations of intermediate diaphragms. The research included a comprehensive literature review; a survey of design agencies; the testing of a full-scale, simple-span, P/C girder-bridge model with eight intermediate diaphragm configurations, as well as a model without diaphragms; and the finite-element analyses of the bridge model assuming both pinned- and fixed-end conditions. The vertical load distribution was determined to be essentially independent of the type and location of the intermediate diaphragms, while the horizontal load distribution was a function of the intermediate diaphragm type and location. Construction details at the girder supports produced significant rotational-end restraint for both vertical and horizontal loading. Both the vertical and horizontal load di...

An analytical model is developed that predicts the out‐of‐plane seismic behavior of reinforced masonry walls. The formulation and implementation of the model are briefly described. The model is validated by comparing the global responses (deflections, moments, and reactions) that it predicts with those obtained from full‐scale dynamic tests on nine clay brick walls and four concrete‐block walls. The test walls cover a typical range of key wall parameters (H/t ratio, amount of vertical reinforcing, presence or absence of grouting and splices, and intensity of vertical load). Each test wall was subjected to a suite of at least 12 earthquake motions, with progressively increasing peak horizontal accelerations of 0.1 g to 0.8 g. An analytical model of each wall is subjected to the same suite of motions measured during the corresponding tests. It is concluded that the analytical model captures the global wall responses well, over the range of wall parameters and earthquake motions included in the tests.

A sliding isolation system consisting of Teflon disc bearings and helical steel springs is described. The springs carry no vertical load and provide bilinear restoring force without hysteresis when deformed in shear. The Teflon disc bearings carry the entire weight of the structure. The isolation system is designed so that the mobilized peak frictional force is larger, by at least a factor of two, than the peak restoring force. Under these conditions the system has a low sensitivity to the frequency content of the input. The system has been evaluated in shake‐table tests of a six‐story, quarter‐scale, 52‐kip (230‐kN) model structure, and is capable of withstanding strong earthquake forces of significant differences in frequency content. Furthermore, the springs are effective in controlling bearing displacements. Also, tests have been carried out without restoring force. In this case excessive permanent displacements are recorded as a result of a small accidental inclination of the sliding bearings. Finall...

This paper summarizes the results of a study conducted to improve design procedures for vertically loaded H-piles in cohesionless soils. Included in the study is the examination of several procedures for estimating residual loads and assumptions concerning the plugging phenomena that may occur between the flanges of an H-pile. Data obtained from full-scale load tests reported in the literature are used to develop the improved design procedures. The improved procedures include a procedure for estimating ultimate bearing capacity and a procedure for developing load-versus-settlement relationships for H-piles in sand. Load-test results from two H-piles that are not part of the data base are included to demonstrate the use of the improved design procedures. The predictions made for these two H-piles using the improved design procedures are closer to the measured load-settlement values than predictions made using existing design methods.

Tests are carried out on 32 reinforced concrete corbels subjected to vertical loading. Steel fibers are used as shear reinforcement in 26 corbels. The main parameters varied are the volumes of main bars and fibrous reinforcements, and the shear-span-to-depth ratio. The results indicated considerable improvement in ductility and strength of corbels as the fiber content was increased. In some instances, it was possible to change the mode of failure from being diagonal splitting or shear to flexure. An empirical equation is presented for estimating the shear strength of corbels based on results reported in this paper and elsewhere. Comparison between the experimental and calculated shear strengths of all corbels tested shows that the two values obtained in each case are in satisfactory agreement.

The results of field tests of bored underreamed pile groups under sustained vertical loads are presented, along with an empirical approach for estimating group efficiencies and load-displacement characteristics of pile groups from the known behaviour of single piles. The effectiveness of available methods for estimating group settlements are compared, resulting in a conservative estimate.

The top and bottom chords consist of continuous prestressed cables which are anchored at each end and between which numerous vertical light rigid spacers are placed. When used in arrays, the cable truss has proved to be a useful structural element by which the roofs of buildings of large span may be supported. Following a general derivation of the equations of vertical equilibrium and compatibility, attention is focused on those cable trusses that are either biconvex or biconcave and initially symmetrical. This essentially removes the nonlinearities that would characterize the asymmetrical truss response to applied vertical load and the analysis is simplified considerably. Detailed solutions are presented for the static response of a symmetrical parabolic truss to a point load, a uniformly distributed load, and a triangular loading block. In the dynamic analyses an investigation is made of the natural frequencies and modes of vertical vibration; the theories are applied to roofs both rectangular and circular in plan.

The theory of elastic, homogeneous, isotropic, thin cylindrical shells under axial symmetric loading is well-know (1). However, the coupling effects of simultaneously applied edge moments, radial shear, and axial loads have not been studied and numerical results applicable to practical cases where edge restraint conditions are uncertain are still lacking. Although the flared edge design is much more economical than welded flat flanges, the penalty is that the vertical load is transmitted to the bottom section through the offset distance, e, to the middle surface of the shell wall. The resulting elastic stresses due to coupled axial forces and bending moments may lead to plastic flow, local buckling, and eventual collapse of such sections. It is the purpose of the present study to predict the coupled elastic stresses that yield upper bounds on the unbuckled stress states.

The Imperial County Services Building was severely damaged during the October 15th, 1979, Imperial Valley Earthquake. The vertical load carrying system and the structural systems used to resist lateral forces are described, and the response of the building is presented using reports of observed damage and acceleration histories measured with thirteen strong‐motion accelerographs located throughout the building. In addition, base‐shear and moment histories derived from measured accelerations are presented. Waveforms are examined for indications of when four first‐story columns at the east end of the structure failed. Dynamic forces acting in either of the directions associated with the two primary lateral‐forceresisting systems are examined to show that forces acting solely in one direction were not responsible for failure of four east‐end columns. Response forces acting in both of the primary directions are considered simultaneously to develop a rationale for failure of east‐end columns.

An extensive experimental study of flexible and semi‐rigid pipes subjected to soil and superimposed loads was carried out in a large laboratory soil box. Normal and tangential soil stresses were measured by plane‐stress transducers at the pipe‐soil interface in a wide trench laying conditions. The results were used to calculate vertical and horizontal soil loads on the pipe. It is shown that both normal and tangential soil stresses are essential for pipe load evaluation. Horizontal to vertical soil load ratios as well as vertical load concentration coefficients are presented for a wide range of pipe‐soil stiffness ratios.

Storage bins, silos, stud wall systems with heavy cladding, and other similar structures often consist of siding supported by vertical stiffeners on one side only. In some cases, the weight of the cladding contributes significantly to the axial load on the stiffeners. In other cases, the fill in such structures often exerts lateral forces on the siding which in turn generates friction forces. The side walls will thus carry a significant vertical load which is usually transmitted to the stiffeners as eccentric distributed axial loads. In either case since the vertical forces can be quite large, the question arises as to how these eccentric forces should be accounted for in the design. The cladding or fill, or both, provides lateral support to some degree. However, designers have had little guidance as to when the moments due to eccentric axial loads can be neglected. The purpose of this paper is to provide such guidance.

Two simple shear apparatus (SSA), the Cambridge University SSA Mk7 and an NGI type, were used to compare the radial stresses developed in the NGI‐type SSA with the horizontal normal stresses on the plane perpendicular to the plane of shear deformation and the intermediate principal effective stresses as measured in the Cambridge University SSA Mk7. These stresses are often assumed to be equal. Monotonic and cyclic simple shear tests were conducted on dense and loose Leighton Buzzard sand at constant applied vertical load. Comparison of results from these tests in the two SSA shows that the radial stresses are equal to neither the horizontal normal stresses nor the intermediate principal effective stresses. These radial stresses do not appear to be valuable in calculating the stress state of a specimen in the NGI‐type SSA. The values of intermediate principal effective stress ratio and the horizontal stress ratio reached at peak stress ratio (maximum shear stress/vertical) in monotonic tests on sand in its...

The cyclic yielding of steel girders in a frame is investigated experimentally. Three sets of frames are subjected to static as well as dynamic cyclic horizontal loading at rates varying from 0.1 cycle/sec. to 3/4 cycle/sec. The first set, free of vertical loads, is forced horizontally into a sinusoidal type motion. The second set is loaded vertically at the beam third points and forced horizontally in a manner similar to the first set. The last set, in addition to vertical load, is forced into a horizontal time deformation similar to that generated by an earthquake. It is concluded that the rate of loading, for the previously mentioned rates, seems to have no significant influence on the response of the frames under all cases of loading.