Buried Arch Research Articles

Seismic Fragility Assessment for a Newly Developed Buried Arch Bridge

This study aims to assess the seismic response of a newly developed buried arch bridge system. The proposed buried arch bridge system is comprised of precast concrete panels, external steel outriggers, and steel V-strips to solve the limitation encountered in the storage, transportation, and construction of traditional buried arch structures. The three-dimensional finite element analysis of this arch system is conducted under dynamic analysis emphasizing the frequency content of earthquakes. Then, the fragility curves are suggested for this arch system based on two damage states defined via incremental dynamic analysis. The results show that this proposed arch system is significantly affected under a high frequency content earthquake compared to the low and intermediate ones. Additionally, the arch system deflects the most at the mid-high position rather than at the arch crown. The deflection at the arch crown or at the mid-high position can be used for establishing the fragility curves as they both connect with the failure mechanism of the arch structure.

Deformation properties of arched glass fiber reinforced plastics structure under static load: Considering the soil cover and rise-span ratio

In this study, the load level, soil cover height, rise-span ratio, and arch foot constraint state were utilized to explore the mechanical properties of buried arch glass fiber reinforced plastics (GFRP) structures. Through the indoor scale-down test, the stress and deformation of arched GFRP structures under different load and soil cover height were investigated. Additionally, through the three-dimensional finite element method, the influence of the rise-span ratio and the constraint state of arch foot on the mechanical properties were obtained. The results indicate the new buried composite arch structure has excellent bearing capacity for the possible traffic load. Simultaneously, the semi-elliptical arch structure was believed to outperform the semi-circular arch structure when considering the external load. Specifically, increasing the soil cover height and reducing rise-span ratio were found to achieve the load-reduction effect.

Full-scale field testing of a precast concrete buried arch bridge with steel outriggers: Field loading test

In this study, field loading tests were conducted to examine the structural response and behaviors of a new type of precast concrete buried arch bridge with steel outriggers (PCASO), consisting of multiple straight precast segments (panels), steel outriggers, and V-strips. Static loading was applied on a full-scale field specimen, approximately 18 m length and 3 m height, for three load cases using concrete weight blocks that quantified its weight one by one using a crane. Finite element (FE) analysis was also conducted following the loading tests on the full-scale field specimen. The loading test results revealed that the deformed shape of the buried arch specimen was similar to the conceptual structural responses of the PCASO system affected by load conditions such as backfill and loading position. The deformed shape for each load case obtained from both the field test results and calculations performed by FE analysis was also compared, and its structural behavior and response calculated using the FE analysis can be confirmed to be relatively similar to the results from the field loading test. Therefore, through this loading test on a full-scale field specimen, the new PCASO system was confirmed to have sufficient structural stability and safety and predictable structural behaviors.

Construction stage analysis of a precast concrete buried arch bridge with steel outriggers from full-scale field test

A new type of Precast Concrete buried Arch bridge with Steel Outriggers (PCASO) was developed to maximize the structural efficiency and improve the constructability of a precast concrete arch system buried underground. In this study, a full-scale field test of Precast Concrete buried Arch bridge with Steel Outriggers (PCASO) was conducted to evaluate the strain and stress state and deformation observed on the concrete panels and steel outriggers during the various construction stages, namely, when the panels were being lifted, and when backfill was being placed on the arch in three stages. The field specimen spanned 6 m and was 2 m high. Displacements were observed in both the vertical and horizontal directions during the backfill construction. However, the final position of the arch was achieved when topsoil was placed on the precast panels. The compressive strains observed on the precast panels increased as the soil was being placed. After the backfill was completed and the topsoil was emplaced, the maximum compressive strains measured on the precast panels were approximately 19% of the compressive strength (which was 8 MPa). During the construction stage, the steel outriggers experienced maximum tensile stresses of approximately 300 MPa, which is close to the service stress level of steel (whose yield strength is 413 MPa). Considering that the outriggers were constructed with thin steel plates and there was little stress change during different construction stages, the nominal stress of the thin plate was checked. The calculated nominal stress based on the measured compressive and tensile stresses ranged between positive and negative 25 MPa. A finite element analysis was conducted following the construction stages of the field test using the field parameters. The analytical study demonstrates that the changes in stress and displacement for each construction stage are comparable between the field measurements and the numerical calculations. Overall, this study validated the structural behaviors of the new type of PCASO through field demonstrations and finite element analyses.

Constitutive models for FE analysis of pile founded buried arch bridge

The paper presents plane strain FE modeling of a pile founded bridge, made from reinforced concrete, by using plate elements for the structure and the soil body. The soil-structure contact is modeled by interface finite elements. The numerical analysis is performed by the Plaxis 2D software. The mechanical behavior of the bridge is approximated by the constitutive models of Hooke and Mohr-Coulomb. Two sets of values of the Mohr-Coulomb strength parameters (cohesion and internal friction angle) for the concrete are obtained - on the basis of the theoretical uniaxial compressive and tensile strengths and on the basis of relationships in the Eurocode 2. The advanced constitutive HSM model is used for the soil. The construction and service periods of the bridge are simulated by a sequence of representative states. The mechanical response of the bridge undergoing backfill and road loads is analysed.

Simulation of Buried Arch Bridge Response to Backfilling and Live Loading

AbstractIn this study, soil–structure interaction in a buried arch bridge system is numerically investigated with two models. Model predictions of arch bending moments and ultimate capacities are compared with the load test performance results of two buried structures from a companion paper. A novel finite-element model was developed using an arch discretized with beam elements and soil discretized with spring elements initialized during progressive backfill simulation. Nonlinear soil-spring force is determined from vertical overburden pressure and earth pressure coefficient dependent on arch deflection. A nonlinear soil-continuum finite-element model was developed using software with Mohr-Coulomb soil plasticity. Experimental moments are compared with model results for backfilling, a series of service-level line loads, and ultimate capacity with an apex line load. The soil-spring model does reasonably well at predicting arch moments and ultimate capacity, and the incorporation of deflection-dependent ear...

Blast-loaded behaviors of severely damaged buried arch repaired by anchored CFRP strips

To strengthen severely blast-damaged buried arch, carbon fiber reinforced polymers (CFRPs) combined with mechanical anchors were applied to repair the structure. A structural model experiment was carried out to check the blast resistance of the repaired arch subjected to underground close-in explosions. The aim of the experiment is to provide believable results of strengthening effects through the dynamic loads, deflections, strains and failure modes. To achieve this objective, blast experiments were performed under 0.6, 3, 2 and 29.4kgTNT charges, respectively. Applied dynamic loads, strains and the failure modes of the strengthened arch by adhering and anchoring CFRP strips were revealed. Adhering/anchoring CFRP strengthening measurement is efficient to restrict debonding failure and let the severely damaged arch have comparable load carrying capacity with the intact arch. Two failure modes, concrete spall depending on the tensile strength of the concrete or mortar and structural plastic collapse relating to the reinforcement ratio of the CFRP strip, were found in segment E and O, respectively. Failure criteria were proposed to describe these two failures and deduce the dynamic load the arch can sustain.

Experimental behaviors of CFRP cloth strengthened buried arch structure subjected to subsurface localized explosion

To improve the anti-blast ability of buried arches, carbon fiber reinforced polymers (CFRPs) were applied to strengthen the concrete arch. A structural model experiment was carried out on a buried scaled-down reinforced-concrete arch structure subjected to underground close-in explosions. The aim of the experiment is to provide believable results of strengthening effects through the dynamic loads, deflections, strains and failure modes. To achieve this objective, blast experiments were carried out under 0.6, 3, 6 and 17.4kg TNT charges, respectively. Distribution laws of the applied dynamic loads, strains and the failure modes of the arch were revealed. Different from the spalling, steel fracture and structural macro-cracks, CFRP strengthened arch renders failure styles as micro-crack belts, composite delamination and structural macro-cracks. Concrete spalling and steel fracture are restricted. Formation of macro-cracks is delayed. Rigidity and load carrying ability are improved.

Dynamic responses of buried arch structure subjected to subsurface localized impulsive loading: Experimental study

A structural model experiment was carried out on a buried scaled-down reinforced-concrete arch structure subjected to underground close-in explosions. The aim of the experiment is to provide believable results of dynamic responses of large-span structures, including the dynamic loads, deflections, strains and failure modes. To achieve this objective, blast experiments were carried out under 0.6 kg, 3 kg, 6 kg and 17.4 kg TNT charges, respectively. Distribution laws of the applied dynamic loads, deflections, strains, accelerations and the failure modes of the arch were revealed. Different from the quasi-uniform distribution style subjected to far-field explosions, the dynamic loads applied on the buried arch subjected to close-in explosions have tense local effects and render a triangle-like distribution style. According to the tested deformations and strains, it can be concluded that subjected to close-in explosions, the buried arch deforms at a dominant flexural mode, companying with compression mode. Spalling, tensile cracks and shear failures of the concrete and yielding of the steel bars are the main failure modes of the blast-loaded arch. The arch will collapse after four or five plastic hinge lines formed. The experimental data are helpful for engineers and well support further theoretical analysis.

Elastic responses of underground circular arches considering dynamic soil-structure interaction: A theoretical analysis

Due to the wide applications of arches in underground protective structures, dynamic analysis of circular arches including soil-structure interactions is important. In this paper, an exact solution of the forced vibration of circular arches subjected to subsurface denotation forces is obtained. The dynamic soil-structure interaction is considered with the introduction of an interfacial damping between the structure element and the surrounding soil into the equation of motion. By neglecting the influences of shear, rotary inertia and tangential forces and assuming the arch incompressible, the equations of motion of the buried arches were set up. Analytical solutions of the dynamic responses of the protective arches were deduced by means of modal superposition. Arches with different opening angles, acoustic impedances and rise-span ratios were analyzed to discuss their influences on an arch. The theoretical analysis suggests blast loads for elastic designs and predicts the potential failure modes for buried protective arches.

Shape optimization of concrete buried arches

Shape optimization in connection with numerical modelling is used to reduce bending and associated flexural stresses in buried concrete arches. Modelling of the arch is carried out via a nonlinear finite element model that accounts for soil constitutive relations, soil–structure interactions, sequential construction stages and soil compaction. Centre line of the arch is parameterized by Bézier curve with three degrees of freedom that are subjected to optimization by genetic and Levenberg–Marquardt algorithm.The paper presents a parametric study which aims to determine the optimal shapes for buried arches of various span/rise ratios, backfill depths and foundation soil types. In the second part of the paper it shows a theoretical reduction in tensile stresses obtained by shape optimization of concrete arch culvert with a 9.4m span tested at the University of Massachusetts at Amherst.

Bending behavior of concrete-filled tubular FRP arches for bridge structures

Concrete-filled fiber-reinforced polymer (FRP) tubes (CFFTs) are seeing increasing use in various infrastructure applications. This paper investigates the bending response of CFFTs for buried arch bridge structures. The thin-walled hybrid composite tubes developed at the University of Maine are fabricated from a combination of E-glass and carbon fiber braid infused with vinyl ester resin. The composite tubes function as confinement, tension and shear reinforcing, eliminating the need for conventional steel rebar. Additionally, the tubes serve as stay-in-place formwork, reducing construction time and complexity relative to conventional cast-in-place concrete structures. The objectives of this study are to experimentally assess the bending response of the concrete-filled FRP arches, compare test results with an analytical model, and illustrate the field application of this technology. To achieve these objectives, the bending load–deformation and moment–curvature response of CFFTs were investigated through quasi-static laboratory testing of three beams and four arches. The specimens were instrumented with displacement transducers and strain gauges at several locations. Two additional arches were subjected to 2,000,000 fatigue cycles and subsequently loaded to failure to assess the effect of fatigue on capacity. A nonlinear beam finite-element model that accounts for concrete confinement and cracking is presented. Model-predicted load–deformation and moment–curvature behavior as well as specimen capacity are shown to compare well with measured data from the arch testing, with arch capacity predicted within 4.2% of the average measured failure load.

Centre-line optimisation of buried arch bridges

The arch is the oldest structural shape that mankind has invented. The Romans constructed a large number of stone arch bridges on roads or water supply routes (aqueducts), many of which have survived to the present day. Arch bridges were constructed throughout medieval times; some of them represent masterpieces of the world´s cultural heritage. Buried concrete arch bridges are built with spans from 2 m up to 40 m on roads and railways, both as underbridges or overbridges, and as pre-cast and cast-in-place structures. Owing to low construction costs, great durability and endurance, they are favoured by contractors and owners. This paper focuses on the structure–soil interaction of buried arch bridges both in operation and under construction. Based on analytical derivation, a method of centre-line optimisation of cast-in-place buried concrete arch bridges is proposed and applied on an existing structure. The method leads to reduction of bending moments and deflections, thus making the structural system more effective. The impact of the construction phases on the distribution of internal forces is studied. Based on the acquired knowledge, modifications of the construction process are proposed and evaluated.

The buried arch structural system for underground structures

In many cases, underground structures are built using conventional above-grade structural systems to carry gravity load. This paper proposes the use of underground arches, termed "buried arches", to support gravity loads, wherein the horizontal thrust of the arch is equilibrated by soil pressure. Because the horizontal soil pressure increases with depth, the depth of the arch may be reduced as the depth below grade increases. Critical to the success of such an approach is a proper accounting of creep and shrinkage for arches made of reinforced concrete. This paper addresses the influence of equilibrium, creep, and shrinkage as they affect the design of the arch from a theoretical perspective. Several examples illustrate the use of buried arches for the design of underground parking structures.

Dynamic Skin‐Friction Effects on Buried Arches

Loads induced by friction as the soil is compacted around embedded structures are especially difficult to quantify. To qualitatively investigate the relative importance of these loads, a dynamic test was conducted on two identical arch structures, in which one structure was covered with a double layer of Teflon to reduce frictional loads as much as possible. At a dynamic peak overpressure of about 1,700 psi (11.7 MPa), the Teflon‐covered arch did not collapse, while the other arch totally collapsed. Results from this test indicate that skin‐friction loads can affect both the maximum capacity and the failure mode of buried arches.

Lessons from Explosive Tests on RC Buried Arches

The response of shallow‐buried reinforced concrete arches under the effects of severe pressure‐time histories that are applied to the free surface is addressed, examined, and discussed. Results from, primarily, three test series are presented and evaluated in light of the known structural behavior and conclusions are drawn about the response of these structures. In the first part of the paper, the writers present the background for the problem and a general overview of past research activities in this area. In the second part of the paper, the emphasis is on four tests, which are presented and discussed in detail. The observed behavioral differences between different types of arches, the effects of two major sources of dynamic loads, and soil‐structure interaction are considered. The conclusions drawn herein are aimed at providing insight into the behavior of buried reinforced concrete arches under dynamic loads and some thoughts on future research in this important area.

Computer Analysis of Newtown Creek Culvert

The design of corrugated-metal buried structures with spans of as much as 25 ft to 50 ft (7.6 m to 15 m) has been largely empirical. Finite element methods of analysis using computers have now been developed to provide a comprehensive and potentially more realistic model of the complex soil-structure interaction problem involved. The structure was a buried arch with a 26-ft (7.9-m) span, 15-ft (4.6-m) rise, and a soil cover of 23 ft (7.0 m). This structure was then thoroughly analyzed using the available finite element computer program, CANDE, developed for the Federal Highway Administration for use in design. The predicted values depended on the soil properties, for which suitable data were not available. This agreement was obtained by selection of the values of the soil properties by successive trials based on a comparison of the computed results with the correct answers for crown deflection and thrust stress. The accuracy of the predictions is therefore not yet proven. In contrast, some characteristics of other measurements, such as horizontal movement of the springline, were not easily predicted.

Blast Loaded Buried Arches

Within the range of parameters investigated, the scaling of the variables associated with the motion of the tested arch floor and the maximum thrust and bending moment are adequately verified. The acceleration, velocity, and displacement of the arch floor scale closely for the response times considered. The variations in thrust and moment from the predicted curve are attributed to model distortions. Four semicircular fixed-end aluminum alloy arches with 4-in., 8-in., 12-in., and 36-in. diameter were buried in dense, dry sand and subjected to air blast pressures at the surface ranging from 70 psi to 300 psi. The geometrically similar arches were tested simultaneously to provide the same pressure on all four arches. The distortion in time was considered insignificant. The series of tests were conducted to investigate and verify model-to-prototype scaling relations for blast loaded buried arches in the elastic and inelastic range of response.

Blast Loading of Small Buried Arches

Abstract : The objective of the work represented by this report was to gain information which will serve as a guide in developing design method for underground structures. In pursuit of this goal, preliminary tests have been conducted on small buried arches to determine the influence of the dominant parameters. Information has been obtained on the response to long-, medium-, and short-duration blast loads including the deflection, thrust, and moment patterns. One static test also was performed. Curves showing the form of arching under static and blast loading are given. In addition, buckling and the variation of interface pressure are discussed briefly. The response of the buried arches consisted primarily of a body motion upon which was superimposed the first inextensional symmetrical mode of vibration. As the entire structure moved downward, the sides moved outward slightly and then inward. It was evident that the passive pressures which developed on the sides played the dominant role in providing resistance. It has been found that in static tests some of the surface load is carried by arching through the soil. In the dynamic tests the inertial forces of the soil above the arch were found to be important. The inertial load overcame the soil shear resistance so that a load approximately equal to the surface load octed on the structure. A model analysis of the system and subsequent comparison of the deflections from the small-structure tests and the Operation Plumbbob Structure 3.3 tests indicate that modeling of deflections is possible.