Concrete Box Culverts Research Articles

Structural Behavior of Concrete Box Culverts under Deep Burial

AbstractCulverts have been used to transmit surface drainage under roadways in place of typical short-span bridges because they provide an economical construction system. In this paper, a numerical...

Analysis of Box Culvert with Different Aspect Ratio

Box culverts are the default buried structure type, where pipe solutions are not suitable. Their larger openings are often required to provide adequate hydraulic capacity. Box culverts are also frequently used for pedestrian or cattle underpasses. The reinforcement used in concrete box culverts can be either conventional bar reinforcement or welded wire fabric. Welded wire fabric has yield strength slightly larger than conventional bar reinforcement. Standard designs for precast concrete box culverts are available with spans varying from 6 to 16 feet and rises varying from 4 to 14 feet. Standard precast concrete box culverts are characteristically invented in 6 foot sections; however larger boxes are fabricated in 4 foot sections to reduce section weight. The designs utilize concrete strengths are suitable for fill heights ranging from less than 2 feet to a maximum of 25 feet. Box culverts outside of the standard size ranges must be custom designed. Each culvert size has three or four classes. Each class has specified wall and slab thicknesses, reinforcement areas, concrete strength, and fill height range to which it applies. To prevent corrosion at the ends of welded wire fabric, nylon boots are required on the ends of every fourth longitudinal wire at the bottom of the form. A maximum of two layers of welded wire fabric can be used for primary reinforcement. If two layers are used, the layers may not be nested. The first box culverts built in Minnesota were made of cast-in-place concrete. The activity of these structures over the years has been very good. Currently, most box culvert installations are precast due to the reduced time required for plan production and construction. Cast-in-place culverts continue to be an allowable option. Buried structures serve a variety of purposes. They are typically used for conveying water. At other times, they are used to provide a grade separated crossing for pedestrian and bicycle traffic. A variety of structure and material types are used. The most prevalent types are pipes and box culverts. Buried structures with horizontal dimensions less than 10'–0 are not classified as bridges. Typically, these smaller buried structures do not need widespread design and are selected from standard design tables. Buried structures with horizontal dimensions greater than or equal to 10'–0 are considered bridges and require a plan prepared by the Bridge Office. All box culverts need a Bridge Office equipped plan as well. In addition to pipes and box culverts, precast concrete arches, precast three-sided structures, and long-span corrugated steel structures are used as buried structures. Buried structures carry vertical loads through a mixture of internal capacity and soil arching around the structure; this is termed soil-structure interaction. The means by which a buried structure carries vertical load varies significantly between different structure types due to their relative stiffness. Concrete box culverts and rigid pipes are categorized as rigid culverts and are supposed to carry the design loads internally with limited requirements or benefit of the soil. Flexible pipe structures (corrugated steel, thermoplastic, etc.) carry loads through soil-structure interaction. For this reason, material and installation requirements of the pipe and soil are well defined including trench or embankment conditions and backfilling and compaction procedures to ensure that the assumed soil-structure capacity is provided and that settlements are not excessive.

Experimental and numerical investigations of thermal properties of insulated concrete sandwich panels with fiberglass shear connectors

A new design of a structural sandwich panel, consisting of a combination of concrete, insulation and connectors, was tested using a hot box apparatus to evaluate its thermal properties and energy efficiency. The three materials of the prefabricated panel were arranged to provide both structural and thermal efficiencies. The main objective of this work was to find the thermal resistance (R-value) of the new panel for different designs. Ten different panels were tested using the hot box approach. Each panel had a unique design in order to determine the effect of the design on the thermal behavior of the panel. The design parameters included the number, size, distribution and material of the connectors, and the number and spacing of the concrete studs. Most of the connectors were made from glass fiber reinforced polymer (GFRP) while steel connectors were used in one panel for comparison purposes. The hot box apparatus was constructed using large precast concrete box culvert units with octagonal cross sections and was carefully insulated. The metering chamber air was heated up to a temperature of 24.5°C and the climate chamber air was reduced to −4.3°C in most cases of the tested panels. The experimental R-values ranged from 2.84 to 4.68m2K/W, compared to 2.74m2K/W for the steel-reinforced control panel. A one-dimensional heat transfer model was also developed to predict the R-values.

Field testing and numerical modeling of a low-fill box culvert under a flexible pavement subjected to traffic loading

This paper presents field study and numerical modeling results for a single-cell low-fill concrete box culvert under a flexible pavement subjected to traffic loading. The culvert in the field test was instrumented with displacement transducers to capture the deformations resulting from different combinations of static and traffic loads. A low-boy truck with a known axle configuration and loads was used to apply seven static load combinations and traffic loads at different speeds. Deflections under the culvert roof were measured during loading. Soil and pavement samples were obtained by drilling operation on the test site. The properties of the soil and pavement layers were determined in the laboratory. A 3-D numerical model of the culvert was developed using a finite difference program FLAC3D. Linear elastic models were used for the pavement layers and soil. The numerical results with the material properties determined in the laboratory were compared with the field test results. The observed deflections in the field test were generally smaller under moving loads than static loads. The maximum deflections measured during the static and traffic loads were 0.6 mm and 0.41 mm respectively. The deflections computed by the numerical method were in good agreement with those observed in the field test. The deflection profiles obtained from the field test and the numerical simulation suggest that the traffic load acted more like a concentrated load distributed over a limited area on the culvert. Elastic models for culverts, pavement layers, and surrounding soil are appropriate for numerical modeling of box culverts under loading for load rating purposes.

전력구 콘크리트 구조물의 건조수축 균열특성에 관한 연구

The purpose of this study is to predict the cracking behavior and suggest the method of controlling the cracking in concrete box culvert for power transmission due to differential drying shrinkage. Drying shrinkage cracking is mainly influenced by the moisture diffusion coefficient that determines moisture diffusion rate inside concrete structures. In addition to the diffusion coefficient, surface coefficient of concrete surface and relative humidity of ambient air simultaneously affect the moisture evaporation from concrete inside to external air outside. Within the framework of drying shrinkage cracking mechanism, it is necessary to perform the numerical analysis, which involves these three influencing factors to predict and control the shrinkage cracking of concrete. In this study, moisture diffusion and stress analysis cor responding to drying shrinkage on concrete box culvert are performed with consideration of diffusion coefficient, surface coefficient, and relative humidity of ambient air. From the numerical results, it is found that cracking behavior due to differential drying shrinkage of box culvert shows the different feature according to three influencing factors and the methodology of controlling of drying shrinkage cracks can be suggested from this study.

Live-Load Effect in Reinforced Concrete Box Culverts under Soil Fill

AbstractThe effects of live load in box culverts may be nearly negligible compared with the effects of dead loads when significant fill is placed above the crown of the culvert. The objective of this study was to determine the effects of live load (truck loads) on reinforced concrete box culverts classified as bridges [spans greater than 6 m (20 ft)] under soil fills of different thicknesses. The study considered the field testing of 10 existing reinforced concrete box culverts with fill depths ranging from 0.76 m (2.5 ft) to 4.1 m (13.5 ft). Instrumentation of the culverts consisted of 12 reusable strain transducers and 12 linear variable displacement transducers. The instrumentation was designed to be applied, used, and removed in one day of testing. Loaded trucks were driven over the culvert to provide live load. The results of the testing show that the live-load effect does diminish with increasing fill depth. The 2012 AASHTO LRFD bridge design specifications are overly conservative in predicting stra...

Influence of Cover Soil Depth on the Load Rating of Reinforced Concrete Box Culverts

This paper describes the influence of cover soil depth on the load rating of the designs of multibarrel, cast-in-place (CIP) reinforced concrete (RC) box culverts and highlights implications for the load rating and design of culvert structures. The basics of culvert load rating are discussed and are followed by a history of culvert design policy and the challenges created by the use of culvert standard designs. A population of Texas Department of Transportation CIP RC standard culvert designs developed between 1930 and 1980 was load rated by using AASHTO policy guidance and a two-dimensional model of direct stiffness structural demand for a full range of cover soil depths. This analysis resulted in a set of 1,081 relationships of load rating versus cover soil depth. Three typical relationships of rating versus depth are illustrated and described in detail. The distribution of characteristic relationships of rating versus depth on the basis of culvert geometry, design cover soil depth, and design era is explored. Cover soil depth is shown to be a critical parameter that must be explicitly considered for the intelligent load rating and design of RC box culverts.

Reliability of concrete box culverts designed for vertical loads

The design vertical loads on box culverts under embankments are commonly calculated using the soil-structure interaction factors ( F e ) recommended by the American Society of Highway and Transportation Officials (AASHTO). Non-linear finite element analyses were used to update F e given by AASHTO by considering the effects of backfill height, culvert stiffness, backfill material stiffness, backfill compaction, and the rigidity of the layer on which the culvert rests. A simplified reliability analysis was performed to determine the adequacy of safety level in AASHTO load resistance factor design (LRFD) code specifications.

폐비닐 골재가 혼합된 시멘트 콘크리트의 열 특성

PURPOSES : In this study, wasted vinyl aggregate, which possesses better thermal properties than natural aggregate, was used in cement concrete mixture to develop more economical concrete with thermal insulation and freeze prevention effects. METHODS : Slump and air content of the fresh concrete, which substituted its 0%, 5%, and 10% of coarse aggregate with wasted vinyl aggregate, were measured. Compressive strength, Poisson`s ratio, elastic modulus, and splitting tensile strength of hardened concrete were measured by laboratory tests. Thermal properties of concrete such as coefficient of thermal expansion, thermal conductivity, and specific heat were also measured according to replacement ratio of wasted vinyl aggregate. Finally, the thermal insulation and freeze prevention effectiveness of the concrete mixed with wasted vinyl aggregate was confirmed through finite element analysis of road pavement crossing above concrete box culvert made from wasted vinyl aggregate. RESULTS : Even though the physical properties of wasted-vinyl-aggregate concrete such as compressive strength, Poisson°Os ratio, elastic modulus, and splitting tensile strength were inferior to those of ordinary concrete, they met requirements for structural concrete. The thermal properties of concrete were improved by wasted vinyl aggregate because it decreased thermal conductivity and increased specific heat of the concrete. According to the result of finite element analysis, temperature variation in pavement subgrade was mitigated by box culvert made from wasted-vinyl-aggregate concrete. CONCLUSIONS : Through the laboratory test and finite element analysis of this study, it was concluded that the concrete structures made from wasted vinyl aggregate showed thermal insulation and freeze prevention effects.

Structural Response of a Low-Fill Box Culvert under Static and Traffic Loading

AbstractBox structures have been commonly used under highways. They are installed at grade or at great depths. When a box culvert is buried at a shallow depth, vertical pressure and dynamic impact due to traffic loading transferred onto the roof of the culvert can induce deflections of the culvert. The effect of the traffic load on the response of the culvert depends not only on the magnitude, pattern, and speed of the traffic load but also on the pavement structure. To investigate these factors, a reinforced concrete box culvert under three roadway sections (concrete pavement, concrete shoulder, and unsurfaced fill) was tested under static and traffic loads. The total thickness of pavement layers was 0.65 m within the pavement section and decreased gradually towards the end of the culvert through the shoulder and the unsurfaced section. The culvert was instrumented with displacement transducers under the roof and pressure cells on top of the roof within the unsurfaced fill. A low-boy truck with a known a...

Evaluation of Production Models for Load Rating Reinforced Concrete Box Culverts

Analyses of two production-oriented culvert load-rating demand models were performed using live-load test data from three instrumented RC box culverts under four cover soil depths. The demand models were a two-dimensional (2D) structural-frame model and a 2D soil-structure interaction model. As expected, increased sophistication in the soil-structure model compared with the structural-frame model resulted in higher precision and accuracy for predicted moments. The impact of modeling accuracy for sections in a culvert where the demand moments approach zero was deemed practically insignificant. When evaluating model accuracy, it is of first importance that the models predict meaningful load magnitudes. Variations in predicted moment accuracy and precision were not uniform but were a function of the location of the critical section in the culvert structure. Improvements in modeling prediction associated with increased modeling sophistication were seen only when the structural-frame model was very imprecise.

ANALYSIS OF BOX CULVERT - COST OPTIMIZATION FOR DIFFERENT ASPECT RATIOS OF CELL

Reinforced concrete box culvert consists of top slab, bottom slab and two vertical side walls built monolithically which form a closed rectangular or square single cell. By using one or more intermediate vertical walls multiple cell box culverts is obtained. Multiple cell reinforced box culverts are ideal bridge structure if the discharge in a drain crossing the road is large and if the bearing capacity of the soil is low the single box culvert becomes uneconomical because of the higher thickness of the slab and walls. In such cases, more than one box can be constructed side by side monolithically. In conventional method thickness of box culvert is assumed and later on check for thickness is taken. But this may leads to uneconomical design therefore an attempt is made to evaluate optimum thicknesses for economical design. In the present work 12 m channel length is consider for analysis with 2m to 6m height variation which is again divided into single cell, double cell and triple cell. IRC class AA tracked live load is considered. The analysis is done by using stiffness matrix method and a computer program in C language is developed for the cost evaluation. Study is carried out related to variation in bending moment; subsequently cost comparison is made for different aspect ratios. The percentage reduction in cost of single cell, double cell and triple cell based on optimum thicknesses are presented. The optimum thicknesses presented over here are used to achieve the economical design of box culvert. Based on these optimum thicknesses optimum cost per meter width of single cell, double cell and triple cell is evaluated. The study reveals that the cost of box culvert reduces if the optimum thicknesses which are presented in this study are considered.

Performance of a Reinforced Concrete Box Culvert Installed in Trapezoidal Trenches

The performance of embankment installation (EI) and trench installation (TI) culverts has been investigated through experimental, numerical, and analytical methods. However, there are few studies on the performance of trapezoidal TI (TTI) culverts. Therefore, this study was performed to investigate the complex soil-structure interaction and to provide reference for the design of TTI culverts. First, field tests were conducted to measure the vertical earth pressure on the TTI culvert. Then, numerical simulations were performed to investigate the performance of TTI culverts. With the validation of the numerical model, parametric studies were carried out to investigate the important influencing factors (i.e., the slope angle of the trench, the bottom width of the trench, the culvert dimensions, and the stiffness of backfill adjacent to the culvert) on the culvert performance. This study reveals that the vertical earth pressure on the TTI culvert is significantly different from that on EI and TI culverts. The magnitude of the vertical earth pressure and deformation of the TTI culvert are influenced by the soil arches as long as the backfill is high enough. Generally, it is suggested that soil arch effects should be considered in the design of TTI culverts.

Stability assessment for highway with large-span box culvert jacking underneath: a case study

A case study of a double-cell, large-span prefabricated reinforced concrete box culvert with a total length of 52 m, a width of 46.8 m, and a height of 9.3 m, which passes beneath the Beijing – Hong Kong –Macau highway, is presented. The culvert is embedded in silty sand and silty clay at a depth of 1.2 m. To ensure the safety and normal operation of the highway, hydraulic jacking with the protection of a pipe roof was adopted for this project. This paper introduces the construction scheme in detail. A three-dimensional numerical simulation of the responses of the highway under which a wide box culvert jacking passes was conducted. The monitoring results on the highway as well as the actual construction process and problems encountered were analyzed. The different development characteristics or trends for the settlement and horizontal displacement of a highway surface are presented. In addition, this paper discusses the reasons for the large deformation of the highway surface as well as proposes reasonable suggestions.

Application of diagnostic load testing and 3D-FEA in load rating of RC box culverts

A refined load rating analysis is performed on four reinforced concrete box culverts using a combination of 3-D finite element analysis and diagnostic load testing. Three of these culverts were constructed prior to the 1940s whereas the fourth one was constructed in 1985. Based on the conventional rating analysis procedures, majority of these culverts would currently be posted for North Carolina legal loads. Culvert types included in this project are comprised of double, triple and quadruple barrels that are either skewed or square and having their unique geometric, material and structural characteristics. The results of the refined load rating procedure indicate that depending on the actual physical condition of the culverts, field measurements, and load test data, the controlling rating factors may increase by up to 270% and decrease by up to 10% when compared with the results of the conventional rating analysis procedures.

Performance of two cast-in-place box culverts under high embankments

Two cast-in-place reinforced concrete box culverts (Longs Creek and McBean Brook culverts) with similar geometry were instrumented to monitor earth pressures. The Longs Creek structure is a 7.30 m wide by 4.53 m high double-cell box under 14.10 m of fill, constructed using the positive projection installation (PPI) method. The McBean Brook structure is a 6.75 m wide by 4.65 m high double-cell box culvert under 25.10 m of fill, constructed using the induced trench installation (ITI) method. Earth pressures were monitored as the fill height above the culvert was increased for both structures. Data from the McBean Brook culvert at a fill height of 14.40 m are compared with the data from the Longs Creek culvert. The similar geometries of these two prototype culverts provide a unique opportunity to compare their performance based on the two different installation methods. For a comparable height of soil cover, measured vertical earth pressures on the roofs were 0.94 and 0.56 times the overburden pressures for ...

박스형 전력구의 콘크리트 탄산화에 의한 잔존수명 예측

박스형 전력구와 같은 지하구조물의 건설은 점점 증가하고 있는 추세이며, 지상구조물에 비해 보수 및 재시공이 어려운 지하구조물의 수명 연장은 매우 중요한 문제로 대두되고 있다. 콘크리트 구조물에서 이산화탄소에 노출된 환경에서 발생하는 탄산화는 콘크리트 내부의 철근을 부식시켜 수명을 저하시키는 요인이 된다. 이 연구에서는 도심지의 두 박스형 전력구에 대한 탄산화 깊이를 측정하여 탄산화에 의한 내구성을 평가하고, 탄산화 측정결과를 바탕으로 몬테카를로 시뮬레이션 기법을 통해 철근의 부식시기를 예측하였다. 탄산화에 의한 기존 도심지의 두 박스형 전력구의 사용수명은 250년 이상으로 예측되었다. The construction of underground structures such as box culverts for electric power transmission is increasing more and more, and the life extension of these structures is very important. Carbonation-induced corrosion in concrete may often occur in a high carbon dioxide environment. In this study, the risk of carbonation of two concrete box culverts in an urban area was evaluated by measuring the carbonation rate and concrete cover depth. Then, the carbonation-free service life at the depth of the steel was calculated, based on in situ information, by the Monte Carlo simulation. The service life of box culvert due to carbonation was estimated over 250 years via Monte Carlo simulation.

Forensic Investigation of Deteriorated Concrete in Plantation East Culverts, City of Benbrook, Texas

Two underground concrete box culverts were installed below ground on Plantation Drive in the City of Benbrook, Texas, in 1991. The culverts consisted of precast segments with case-in-place (CIP) collars/bends. The concrete started deteriorating and spalling at several CIP bend locations as early as 1993. The concrete continued to deteriorate over the subsequent years. An investigation was launched herein to determine the cause and extent of the concrete degradation. The geotechnical investigation involved resistivity imaging, soil boring, and photo-ionic detection for exploring any soil contamination around the culverts that may enhance the concrete deterioration. Visual inspection of the deteriorated concrete helped to examine the clear concrete cover. Concrete cores were taken and tested for strength and deterioration. No soil contamination was observed at the site. The culvert water acidity was neutral. Therefore, the contamination in the underground tunnel/box culvert may not be related to the soil contamination or leakage from sewerage pipes around the culvert areas. The collected concrete core inspection and testing showed that most of the bend concrete is badly deteriorated. Although the strength of some of the more intact bends is acceptable, most of the bend concrete simply does not have sufficient strength, integrity, and ductility to effectively carry the service loads imparted on them. The rebars inside the cores were extensively deteriorated and lost much of their strengths and ductility. The visual inspection showed that the insufficient clear covers were used in the culvert wall and the slab; this was the likely cause of the premature concrete deterioration. On the basis of the investigation performed herein, immediate rehabilitation steps were recommended.

Erratum for “Development Formulation for Structural Design of Concrete Box Culverts” by Alia Osman Mohamed Ahmed and ElHussein Alarabi

Erratum for “Development Formulation for Structural Design of Concrete Box Culverts” by Alia Osman Mohamed Ahmed and ElHussein Alarabi

Detection and Reinforce of a Reinforced Concrete Box Culvert Suffered a Conflagration

When a reinforced concrete structure suffers from a big fire, its quality will change and its bearing ability will be reduced. It is necessary to take a comprehensive testing and to formulate corresponding reinforcement to restore the structure. This article mainly talks about a series of detections and their results of a reinforced concrete culvert which suffered from fire, and then selects a better reinforcement program. It can provide reference for the reinforcement of similar concrete structures.