See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/340102718 Design of a Box Culvert Thesis · May 2018 DOI: 10.13140/RG.2.2.16490.47041 CITATIONS READS 0 118,934 1 author: Ola Adel Qasim Al-Mansour University College 69 PUBLICATIONS 201 CITATIONS SEE PROFILE Some of the authors of this publication are also working on these related projects: Special Issue "The Business Ecosystem Research of the Environmental Goods and Services Sector" View project Behavior of Pile Rafts with Raft Size, Number of Piles and Different Pile Length View project All content following this page was uploaded by Ola Adel Qasim on 23 March 2020. The user has requested enhancement of the downloaded file. Republic of Iraq Al-Mansour University College Civil Engineering department Research project Study year 2017-2018 Design of a Box Culvert This project is in partial fulfillment of the requirements for a B.Sc. in Civil Engineering Prepared By Ali Mahdi Mohammed Ahmed Nafie Mohammed Mohammed Abd Al-Amir Hussain Mutaz Nather Majid Supervised by Dr. Ola Adil Qassim A.D 2018 Baghdad The Hegira Date:1439 SUPERVISOR’S CERTIFICATE I certify that the preparation of the project entitled: Design of a Box Culvert was prepared under my supervision at Al-Mansour University College as a partial fulfillment of the requirements for a B.Sc. Degree in Civil Engineering. Supervisor’s Signature: Name: Date: COMMITTEE CERTIFICATE We certify that the project entitled: Design of a Box Culvert was prepared, corrected and defended by the students and in our opinion, it meets the standards of a graduation project for a B.Sc. Degree at Al-Mansour University College. Signature: (Chairman) Name: Date: Signature: (Member) Name: Date: Supervisor Signature: and (member) Name: Date: Abstract ABSTRACT When it is required to construct a road that intersects with a natural stream flow or a water canal, the major problem shows as how to the keep the stream flows without threatening the roadway and the passing vehicles due to water rising when flooding at raining seasons or overflow in the canal. For this purpose, a culvert is must be constructed in the intersections. A culvert is a structure designed to allow passing of water through. It’s required to design a box culvert in Kut-Petera irrigation project at the intersection of main drain (MD-A) and Al-Dejaili paved road. The design is carried out on the basis of hydraulics and structure limitations. The hydraulic design is based on the obtained hydraulic data of the area. The dimensions of the box culvert were obtained from the hydraulic design. The designed box culvert is a two cell with a total length of 27m and total width of 3.14m. The structural design is defined as the stability and safety of the box culvert from the applied loads. After designing based on the maximum bending moment and shear value, the required reinforcements are ¨ ∅16 @ 300 mm C*C (EF⁄V) and ∅12 @ 250 mm C*C (EF⁄H) 𝑓𝑜𝑟 𝑡ℎ𝑒 𝑤𝑎𝑙𝑙𝑠. ¨ ∅12 @ 250 mm C*C at top and bottom for the top and bottom slabs. Design of Box Culvert I List of Contents Title Page I II III IV V Abstract List of Contents. List of Symbols List of Tables. List of Figures. Chapter One: Introduction 1-1 Introduction 1-2 Aim of the study 1-3 Objectives 1-4 Content 1 2 2 2 Chapter Two: Review of Literature 2-1 General 2-2 Function of Culvert 2-3 Culverts and Bridges 2-3-1 Economic Considerations 2-4 Service Life 2-5 Inlets 2-6 Culvert Hydraulics 2-6-1 Flow Through Culverts 2-7 Types of Flow Control 2-7-1 Inlet Control 2-7-2 Outlet Control 2-8 Headwater 2-9 Culvert Length. 2-10 Box Culvert and Pipe Culvert 2-11 Culvert Failure 2-12 Environmental Impacts 2-13 Velocity Limitation 2-14 Structural Design of Box Culvert 2-14-1 Box Culvert Structural Elements 2-14-2 Applied Load 2-14-3 Structural Design Method Chapter Three: Theoretical Background 3-1 Introduction 3-2 Hydraulic Design information 3-3 Conveyance condition 3-4 Case 4 formula 3-5 Structural Design Cases Chapter Four: Results and Discussion 4-1 Hydraulic Design. 4-2 Structural Design. 4-3 Reinforcement Details Chapter Five: Conclusions and recommendations 5-1 Conclusions. 5-2 Recommendations. 3 4 4 5 6 7 8 8 12 12 13 15 15 16 17 17 18 18 19 19 20 21 23 25 26 29 30 37 52 53 53 References Appendix Design of a Box Culvert II List of Symbols Symbol Definition B Drain bed width D Span of box culvert section D/S W. L Downstream water level H Headwater H` Critical headwater ∆H Total head losses hf major losses due to friction hm minor losses due to entrance and exit k Coefficient of losses n Manning coefficient Q Discharge S Longitudinal slope U/S W. L Upstream water level V Velocity W Thickness of box culvert section wall Design of a Box Culvert III List of Tables Table No. Subject PAGE NO. Chapter Two: Review of Literature (2-1) Factors influencing culvert design 14 Chapter Four: Results and Discussion (4-1) Summary of factored distributed loads 40 (4-2) Moment distribution table 43 (4-3) Negative moment at face of support 45 (4-4) Moments summary 46 (4-5) Vu at the face of support. 46 (4-6) Vu at distance d from support face. 47 (4-7) Reinforcement calculations. 49 (4-8) ETABS results. 51 Design of a Box Culvert IV List of Figures Figure No. PAGE NO. Subject Chapter Two: Literature Review (2-1) (2-1) (2-3) (2-4) (2-5) (2-6) (2-7) (2-8) (2-9) (2-10) (2-11) (2-12) (2-13) (2-14) (2-15) (2-16) (2-17) Box Culvert Pipe Culvert Different Cross Sections of Culverts Bridge Versus Culvert at Same Location Four Standard Inlet Types Entrance Condition Flow in a Culvert Case 1 of Culvert Flow Case 2 of Culvert Flow Case 3 of Culvert Flow Case 4 of Culvert flow Case 5 of Culvert Flow Case 6 of Culvert Flow Typical Inlet Control Flow Section. Typical Outlet Control Flow Section. Roadway Cross Section and Culvert Length. Small Spatial Requirement of Box Culvert Than Pipes. 3 3 4 5 7 8 8 9 10 10 11 11 12 13 14 15 16 Chapter Three: theoretical background (3-1) (3-2) (3-3) (3-4) (3-5) (3-6) Sector 3 of the Kut-Petera Irrigation Project Section of MD-A with Culvert Location The Profile Between the Stations (5+000 – 11+500) km Case 4 Total Head Losses Cross Section of Box Culvert 21 22 24 25 26 27 Chapter Four: Results and Discussion (4-1) (4-2) (4-3) (4-4) (4-5) (4-6) (4-7) (4-8) (4-9) (4-10) (4-13) Main Drain (MD-A) Cross Section Culvert side view [invert level = main drain (MD-A) level] Culvert side view when H<H’ Culvert side view with 0.73 m length invert Culvert side view of a single box when H < H` Culvert side view with 0.2 m length invert Section A-A Factored load distribution Frame of box culvert Typical slab reinforcement Section A-A reinforcement details Design of a Box Culvert 30 30 31 32 33 34 36 39 41 52 52 V Chapter One Introduction Chapter one Introduction Chapter One Introduction 1-1 Introduction A hydraulic structure is a structure submerged or partially submerged in any body of water, which disrupts the natural flow of water. They can be used to divert, disrupt or completely stop the flow. A hydraulic structure can be built in rivers, a sea, or any body of water where there is a need for a change in the natural flow of water. Culvert is a hydraulic structure that allows water to flow under a road, railroad, trail, or similar obstruction from one side to the other side. Typically embedded so as to be surrounded by soil. Culverts can be constructed of a variety of materials including cast-in-place or precast concrete. Culverts are commonly used both as cross-drains for ditch relief and to pass water under a road at natural drainage and stream crossings. A culvert may be a bridge-like structure designed to allow vehicle or pedestrian traffic to cross over the waterway while allowing adequate passage for the water. Culverts come in many sizes and shapes including round, elliptical, and box-like constructions. The culvert type and shape selection are based on a number of factors including requirements for hydraulic performance, limitation on upstream water surface elevation, and roadway embankment height. The structural design involves consideration of load cases (box empty, full, surcharge loads etc.) and factors like live load, effective width, braking force, dispersal of load through fill, impact factor, co-efficient of earth pressure etc. The structural elements are required to be designed to withstand maximum bending moment and shear force. Relevant Codes are required to be referred. Design of Box Culvert Chapter one Introduction 1-2 Aim of the project It is required to design a box shaped culvert on the basis of hydraulics and structural requirements in Kut-Petera irrigation project at the intersection between main drain (MD-A) and Al-Dejaili paved road. 1-3 Objectives The main objectives of this project are summarized as follow: 1. Hydraulically design of a box culvert in Kut-Petera irrigation project at the intersection between main drain (MD-A) and Al-Dejaili paved road. 2. Determine the total loads acting on the various parts of the box culvert. 3. Suitable structure design for the box culvert. 4. Design reinforcement steel for the culvert. 5. Analysis the structurally designed box culvert using ETABS software. 1-4 Content This study is divided into the following: • Chapter One: Introduction. • Chapter Two: Review of Literature. • Chapter Three: Theoretical Background. • Chapter Four: Results and Discussion. • Chapter Five: Conclusion and Recommendations. Design of Box Culvert Chapter Two Review of Literature Chapter Two Review of Literature Chapter Two Review of Literature 2-1 General Creamer (2007) introduced culvert as a structure that allows water to flow under a road, railroad, trail, or similar obstruction from one side to the other side, typically embedded so as to be surrounded by soil. A culvert may be constructed of a variety of materials including cast-in-place or precast concrete (reinforced or non-reinforced), galvanized steel, aluminum, or plastic, typically high-density polyethylene. Culverts come in many sizes and shapes including round, elliptical, flat-bottomed, pear-shaped, and box-like constructions. The culvert type and shape selection are based on a number of factors including requirements for hydraulic performance, limitation on upstream water surface elevation, and roadway profile, flood damage evaluations, construction and maintenance costs, and estimates of service life. Figure (2-1). Box Culvert. Design of Box Culvert Figure (2-2). Pipe Culvert. 3 Chapter Two Review of Literature Figure (2-3). Different cross sections of culverts. 2-2 Function of Culverts Kilgore, et. al (2012) reported that culverts perform a wide range of hydraulic and non-hydraulic functions. The most common hydraulic function is providing cross drainage for a stream channel. Other hydraulic functions include floodplain relief, where a culvert might be placed in the overbank of a wide floodplain to provide drainage of the overbank area during large flood events. Such culverts often have no defined channel upstream or downstream of the barrel and may be dry for years at a time. Smaller culvert structures often function to provide ditch relief for drainage ditches along a roadway, diverting some of the discharge from the ditch. Non-hydraulic functions include crossing structures for human or animal traffic, such as a pedestrian or trail crossing, cattle crossings, farm equipment access and crossings designed to facilitate wildlife movement. 2-3 Culverts and Bridges Creamer (2007) explained that culvert may be a bridge-like structure designed to allow vehicle or pedestrian traffic to cross over the waterway while allowing adequate passage for the water. The major benefits of the culvert are: • Decreased traffic interruption time due to roadway flooding. • Increased driving safety. Comparing culverts to bridges the designer must determine which type of structure is best for a particular location, and then decide how to analyze the Design of Box Culvert 4 Chapter Two Review of Literature crossing. For example, in many respects a large box culvert begins to resemble a small single-span bridge with vertical wall abutments, so culverts are used: • Where bridges are not hydraulically required. • Where debris and ice potential are tolerable. • Where more economical than a bridge. Safety, aesthetic and economic considerations are involved in the choice of a bridge or culvert. 2-3-1 Economic Considerations Kilgore, et al. (2012) reported that economic considerations were of primary importance in deciding between the use of a bridge or a culvert at stream crossings where either will satisfy hydraulic and structural requirements. The initial cost for a culvert is usually less than a bridge since the use of increased headwater at a culvert installation normally permits the use of a smaller opening – figure (2-4) – compared to a bridge which is normally designed with freeboard at the design discharge. However, this advantage must be balanced against possible flood damages associated with increased headwater, especially at higher discharges. Figure (2-4). Bridge versus culvert at same location. Design of Box Culvert 5 Chapter Two Review of Literature The major costs are associated with the construction of the roadway embankment and the culvert itself. The design of a culvert installation should always include an economic evaluation. A wide spectrum of flood flows with associated probabilities will occur at the culvert site during its service life. Maintenance of the facility and flood damage potential must also be factored into the cost analysis. The benefits of constructing a large capacity culvert to accommodate all of these events with no detrimental flooding effects are normally outweighed by the initial construction costs. Thus, an economic analysis of the tradeoffs is performed with varying degrees of effort and thoroughness. The ideal culvert selection process minimizes the total annual cost of the installation over the life of the roadway. The need to compare the cost of available shapes and sizes is well understood when designing a culvert. Selecting a culvert material that better withstands corrosion may cost more initially, but the longer service life will lower total annual cost. The annual cost includes capital expenditures, maintenance costs, and risks associated with flooding. Anticipating future maintenance requirements can also save money in the long run. Maintenance costs for culverts may result from channel erosion at the inlet and outlet, erosion and deterioration of the culvert invert, sedimentation, and embankment repair in case of overtopping. 2-4 Service Life Kilgore, et al. (2012) stated that the desired service life of the culvert should be considered in the selection process where the service life of the culvert should match the installation. If the culvert is in a location where replacement would be impractical, the service life of the culvert should equal the service life of the roadway. If rehabilitation is feasible, or if it is determined that the roadway will be rebuilt in a relatively short time, a culvert with a shorter service life should be selected. Design of Box Culvert 6 Chapter Two Review of Literature 2-5 Inlets Kilgore, et al. (2012) defined a multitude of different inlet configurations are utilized on culvert barrels. These include both prefabricated and constructedin-place installations. Commonly used inlet configurations include projecting culvert barrels, cast-in-place concrete headwalls, precast or prefabricated end sections, and culvert ends mitered to conform to the fill slope – figure (2-5) –. Hydraulic performance, structural stability, aesthetics, erosion control, and fill retention are considerations in the selection of various inlet configurations. Figure (2-5). Four standard inlet types. The hydraulic capacity of a culvert may be improved by appropriate inlet selection. The channel is often wider than the culvert barrel, causing a contraction at the culvert inlet which may be the primary flow control. The provision of a more gradual flow transition will lessen the energy loss and thus create a more hydraulically efficient inlet condition – figure (2-6) –. Beveled edges are therefore more efficient than square edges. Design of Box Culvert 7 Chapter Two Review of Literature Figure (2-6). Entrance Condition. 2-6 Culvert Hydraulics Kailan (2015) stated that a complete theoretical analysis of culvert hydraulics based on fundamental equations can be difficult. Flow conditions vary over time for any given culvert. The barrel of the culvert may flow full or partly full depending upon upstream and downstream conditions, barrel characteristics, and inlet geometry. 2-6-1 Flow Through Culverts Kailan (2015) stated that the inlet will not be submerged if the headwater is less than a critical value (H), while the outlet is not submerged. 1.2D ≤ H ≤ 1.5D where D = culvert height A culvert with a square edge at the top of the entrance will not flow full even if the inlet is below head water level when the outlet is not submerged. Separation Culvert seal Figure (2-7). Flow in a culvert. Design of Box Culvert 8 Chapter Two Review of Literature For practical purposes, culvert flow may be classified into 6 types of flow within 2 groups. Group (A) Free surface flow (inlet and outlet) throughout (neither end submerged). Case 1 Critical depth at inlet (inlet control). H < 1.2D yt < yc Culverts on supercritical slopes, inlet not submerged, free outlet, control at inlet, flow is supercritical. So>Sc Figure (2-8). Case 1 of culvert flow. In this case discharge is independent of slope, roughness, length, outlet type, shape and size of the barrel. It depends entirely on the inlet geometry and the headwater elevation. æHö Q = Bg ç ÷ è 1.5 ø 1.5 1/2 Design of Box Culvert where B is the width of the box section 9 Chapter Two Review of Literature Case 2 Critical depth at outlet (outlet control). H < 1.2D yt < yc Figure (2-9). Case 2 of culvert flow. Culverts on subcritical or horizontal slope, hence the control section is at the outlet. Discharge depends on inlet geometry, headwater elev., shape, size of barrel, roughness, slope and length. Case 3 Sub critical flow case. Culverts on subcritical slopes, it does not flow full. H < 1.2D yt > yc Figure (2-10). Case 3 of culvert flow. Design of Box Culvert 10 Chapter Two Review of Literature Group (B) Upstream end of culvert is always submerged. Case 4 Inlet and outlet are submerged. It is the most economical case, which is usually used in design. The conduit is flowing full. H>D yt > D Submerged outlet H > 1.2D full flow Yt > D Figure (2-11). Case 4 of culvert flow. Case 5 Submerged inlet, full flow, free outlet, culverts on mild (subcritical) or horizontal slopes. H > 1.2D yt < D In this case, the culvert is hydraulically long. Figure (2-12). Case 5 of culvert flow. Design of Box Culvert 11 Chapter Two Review of Literature Case 6 Partly full flow, submerged inlet, Rapid flow case at entrance, free outlet, Hydraulically short, control at inlet. Orifice flow. Figure (2-13). Case 6 of culvert flow. The flow is analogous to a sluice and the equation of discharge becomes: - Q = C d .B.D.(2gH ) 1/ 2 Cd = 0.42 + 0.05 H D For 1.2 < H < 4 in meters system D 2-7 Types of Flow Control Kilgore, et al. (2012) stated that inlet and outlet control are the two basic types of flow control defined in the research conducted by the National Bureau of Standards (NBS) and the Federal Highway Administration (FHWA). The basis for the classification system was the location of the control section. The characterization of pressure, subcritical, and supercritical flow regimes played an important role in determining the location of the control section and thus the type of control. The hydraulic capacity of a culvert depends upon a different combination of factors for each type of control. 2-7-1 Inlet Control Kilgore, et al. (2012) observed that inlet control occurs when the culvert barrel is capable of conveying more flow than the inlet will accept. The control section of a culvert operating under inlet control is located just inside the Design of Box Culvert 12 Chapter Two Review of Literature entrance. Critical depth occurs at or near this location, and the flow regime immediately downstream is supercritical. Figure (2-14) shows one typical inlet control flow condition. Hydraulic characteristics downstream of the inlet control section do not affect the culvert capacity. The upstream water surface elevation and the inlet geometry represent the major flow controls. The inlet geometry includes the inlet shape, inlet cross-sectional area, and the inlet configuration (Table 2-1). Figure (2-14). Typical inlet control flow section. 2-7-2 Outlet Control Kilgore, et al. (2012) observed that outlet control flow occurs when the culvert barrel is not capable of conveying as much flow as the inlet opening will accept. The control section for outlet control flow in a culvert is located at the barrel exit or further downstream. Either subcritical or pressure flow exists in the culvert barrel under these conditions. Figure (2-15) shows two typical outlet control flow conditions. All of the geometric and hydraulic characteristics of the culvert play a role in determining its capacity. These characteristics include all of the factors governing inlet control, the water surface elevation at the outlet, and the barrel characteristics (Table 2-1). Design of Box Culvert 13 Chapter Two Review of Literature Figure (2-15). Typical outlet control flow section. Table (2-1) Factors influencing culvert design. Factor Inlet control Outlet control Headwater x x Area Shape Inlet configuration x x x x x x Barrel roughness - x Barrel length - x Barrel Slope Tailwater x - x x * For inlet control the area and shape factors relate to the inlet area and shape. For outlet control, they relate to the barrel area and shape. Design of Box Culvert 14 Chapter Two Review of Literature 2-8 Headwater Kilgore, et al. (2012) noted that energy is required to force flow through a culvert. This energy takes the form of an increased water surface elevation on the upstream side of the culvert. The depth of the upstream water surface measured from the invert at the culvert entrance is generally referred to as headwater depth. The allowable headwater is the maximum possible headwater, or ponding depth, at the upstream side of the culvert. Note that this is different from the design headwater. The design headwater is actual headwater that will occur for the selected culvert as designed. 2-9 Culvert Length Creamer (2007) stated that important dimensions and features of the culvert will become evident when the desired roadway cross section is measured or established. The dimensions are obtained by superimposing the estimated culvert barrel on the roadway cross section and the streambed profile, Figure (2-16). This superposition establishes the inlet and outlet invert elevations. Figure (2-16) Roadway cross section and culvert length. Design of Box Culvert 15 Chapter Two Review of Literature 2-10 Box Culvert and Pipe Culvert Civil Engineering Portal website (2012) published that in terms of hydraulic performance, circular section is the best geometrical sections among all. Therefore, for relative small discharge, precast concrete pipes and ductile iron pipes are normally used which are circular in shape. But for applications of very large flow, precast concrete pipes and ductile iron pipes may not be available in current market. In this condition, cast-in-situ construction has to be employed. It is beyond doubt that the fabrication of formwork for circular shape is difficult when compared with normal box culvert structures. However, circular shape is the most hydraulic efficient structure which means for a given discharge, the area of flow is minimum. Therefore, it helps to save the cost of extra linings required for the choice of box culverts. However, box culverts do possess some advantages. For example, they can cope with large flow situation where headroom is limited because the height of box culverts can be reduced while the size of pipe culverts is fixed. Secondly, for some difficult site conditions, e.g. excavation of structure in rock, for the same equivalent cross-sectional area, the width of box culverts can be designed to be smaller than that of pipe culverts and this enhances smaller amount of excavation and backfilling. Figure (2-17). Small spatial requirement of box culvert than pipes. Design of Box Culvert 16 Chapter Two Review of Literature 2-11 Culvert Failure Pencol Engineering Consultants (1983) stated that culvert failures can occur for a wide variety of reasons including maintenance, environmental, and installation related failures, functional or process failures related to capacity and volume causing the erosion of the soil around or under them, and structural or material failures that cause culverts to fail due to collapse or corrosion of the materials from which they are made. If the failure is sudden and catastrophic, it can result in injury or loss of life. Sudden road collapses are often at poorly designed and engineered culvert crossing sites. Water passing through undersized culverts will scour away the surrounding soil over time. This can cause a sudden failure during medium-sized rain events. Accidents due to culvert failure can also occur if a culvert has not been adequately sized and a flood event overwhelms the culvert or disrupts the road or railway above it. Ongoing culvert function without failure depends on proper design and engineering considerations being given to load and water capacities, surrounding soil analysis, backfill and bedding compaction, and erosion protection. Improperly designed backfill support around aluminum or plastic culverts can result in material collapse or failure from inadequate load support. 2-12 Environmental Impacts Chanson and Wang (2017) conducted a study about safe and stable stream crossings can accommodate wildlife and protect stream health while reducing expensive erosion and structural damage. Undersized and poorly placed culverts can cause problems for water quality and aquatic organisms. Poorly designed culverts can degrade water quality via scour and erosion and also restrict aquatic organisms from being able to move freely between upstream and downstream habitat. Fish are a common victim in the loss of habitat due to poorly designed Design of Box Culvert 17 Chapter Two Review of Literature crossing structures. Culverts that offer adequate aquatic organism passage reduce impediments to movement of fish, wildlife and other aquatic life that require instream passage. These structures are less likely to fail in medium to large scale rain and snow melt events. Poorly designed culverts are also more suitable to become jammed with sediment and debris during medium to large scale rain events. If the culvert cannot pass the water volume in the stream, the water may overflow over the road embankment. This may cause significant erosion, washing out the culvert. The embankment material that is washed away can clog other structures downstream, causing them to fail as well. It can also damage crops and property 2-13 Velocity Limitation Pencol Engineering Consultants (1983) considered velocity limitations include the maximum and the minimum velocities that should be considered when designing a culvert, the outlet velocity affects the stability of the culvert, the greater the outlet velocity the greater the need for stability, there is no specified maximum velocity for reinforced concrete box culverts, but there should be provision of outer protection when the velocity is an erosion risk. However, velocity should not be less than 0.5 m/s to prevent sedimentation in the barrel of the box culvert and should not be more than 1.5 m/s to prevent corrosion of the box culvert barrel. 2-14 Structural Design of Box Culvert Bolden, et al. (2016) stated that the culvert design begins when the structure design unit receives the culvert hydraulic design report. This report shall be used to contained the culvert length, design fill, and other items that lead to the completed culvert plans. Design of Box Culvert 18 Chapter Two Review of Literature Pencol Engineering Consultants (1983) defined box culverts are reinforced concrete closed rigid frames which must support vertical earth and truck loads and lateral earth pressure. They may be either single or multi-cell based on the hydraulic requirements. Garg (2007) reported that box culverts are typically designed similar to bridges, and the new design concepts for bridges are based on the Load and Resistance Factor Design (LRFD) which were developed by the AASHTO. Box culvert’s four sides are built monolithically and also provide haunch at corners to decrease the water pressure effect. In this type of culvert there is no need of extra foundation since bottom slab act as mat foundation. 2-14-1 Box Culvert Structural Elements Kumar and Srinivas (2015) stated that box Culverts consist of top slab, bottom slab and two vertical side walls. Reinforced concrete rigid frame box culverts are used for square or rectangular openings. The top of the box section can be at the road level or can be at a depth below road level with a fill depending on site conditions. Pencol Engineering Consultants (1983) assumed the thickness of the box culvert and later checked in conventional method. However, this may lead to uneconomical design therefore an attempt is made to evaluate optimum thicknesses for economical design. 2-14-2 Applied Loads Kumar and Srinivas (2015) classified loads subjected to box culvert to dead load and live load. Dead load comprising of self-weight of top and bottom slab of the culvert and two side walls of the structure which is calculated based on clear dimensions of the culvert and thickness of the culvert. Super imposed dead load depends on the typed of the constructed road above the culvert and is calculated from standards and specifications code of practice. Live load on culvert Design of Box Culvert 19 Chapter Two Review of Literature is vehicular loading. The vehicular live load consists set of wheel loads moving on top slab of culvert. These loads are distributed through the top slab of the culvert. Earth can exert pressure as active and passive. Minimum is active and maximum is passive earth pressure and the median is rest. Chandrakant and Malgonda (2014) concluded that, since box culvert carries earth embankment which is subjected to same traffic loads as the road carries and therefore, it is required for the box culvert to be designed for such loads. The structural elements are required to be designed to withstand maximum bending moment and shear force. Analysis of box culvert is carried out for various load conditions and structural design is suggested for critical cases. Kim and Yoo (2002) conducted an investigation for deeply buried structures, the dead weight of soil itself is the main design load and the effect of live loads is not considered significant. AASHTO LRFD Bridge Design Specifications stipulate the computation of the design load on the top slab of the box culvert based primarily the effective density on the concrete box culverts can be depending on the installation method, trench installation. 2-14-3 Structural Design Method Oyenuga (2001) stated that a box culvert should be designed as a rigid structure with moments occurring at the corners using the method of moment distribution. The analysis carried out for the following cases: • Culvert empty: Full load on top of the slab, surcharge load and superimposed surcharge load on earth fill. • Culvert full: Live load surcharge on top slab and no superimposed surcharge on earth fill. • Culvert full: Live load surcharge on top slab and superimposed surcharge load on earth fill. Design of Box Culvert 20 Chapter Three Theoretical Background Chapter Three Theoretical Background Chapter Three Theoretical Background 3-1 Introduction The Kut-Petera irrigation project is of an area of 157,000 donum and consists of many sectors. Sector 3 is located in Al-Kut side and its area is 22,000 donum. The irrigation network in sector 3, as shown in figure (3-1), has an irrigation network contains a main cannel which takes water from The Tigers river then distributes it into branch cannels, as well the drainage network. The section of main drain (MD-A), shown in figure (3-2), is 35 km in length and intersected with Al-Dejaili paved road at the station (10 + 660) km where the culvert is constructed. Figure (3-1). Sector 3 of the Kut-Petera irrigation project. Design of Box Culvert 21 Chapter Three Theoretical Background Figure (3-2). Section of MD-A with culvert location. Design of Box Culvert 22 Chapter Three Theoretical Background 3-2 Hydraulic Design information The profile shown in figure (3-3) is a section between the stations (5+000 – 11+500) km. At the station (10+660) km is the culvert location and the design information are obtained from the profile. Design information of MD-A is: • Discharge (Q) = 1.95 m3/s • Velocity (V) = 0.297 m/s • Drain bed width (B) = 3.5 m • Drain water depth (H) = 1.25 m • Side slope = 2:1 • Longitudinal slope (S) = 10 cm/km • Ground level = 12.99 m • Manning coefficient (n) = 0.015 • Upstream water level (U/S W.L) = 8.56 m • Downstream water level (D/S W.L) = 8.51 m • Inlet bed level = 7.31 m • Outlet bed level = 7.26 m As for the road, the design information is: • Top level of road = 12.99 m • Top width of road = 10 m (two lanes each 3 m and two shoulders each 2 m). • Side slope = 2:1 Finally, the structural design information is: • 𝛾"#$"%&'& = 24 𝐾𝑁/𝑚0 • 𝛾1#23 14'. = 18 𝐾𝑁/𝑚0 Design of Box Culvert 23 Chapter Three Theoretical Background Figure (3-3). The profile between the stations (5+000 – 11+500) km. Design of Box Culvert 24 Chapter Three Theoretical Background 3-3 Conveyance condition The used conveyance condition for this culvert design is case 4, as explained in chapter two, because of the economic benefit. Whereas, the topography of Iraq is relatively flat, so, to achieve the required slope, it will be a high cost of cut and fill works. Secondly, Head losses have to be minimized as well keeping the adequate velocity of the flow, as the high velocity will lead to erosion of the cannel sides especially it is not filled with concrete and the low velocity will lead to sedimentation of sediments of the water in the cannel. Submerged outlet H > 1.2D full flow Yt > D Figure (3-4). Case 4. Design of Box Culvert 25 Chapter Three Theoretical Background 3-4 Case 4 formula The total head losses - showing in figure (3-5) - of the water flowing in the box culvert is based on the basis of energy losses due to: • Major losses due to friction, and; • Minor losses due to entrance and exit. The total head losses equation is: DH = ℎ9 + ℎ; … … (𝑒𝑞. 3 − 1) Where: DH = Total head losses ℎ9 = major losses due to friction ℎ; = minor losses due to entrance and exit ℎ; is at the inlet and outlet of the box culvert, therefore, DH = ℎ9 + ℎ; )2$3&' + ℎ; )#C'3&' … … (𝑒𝑞. 3 − 2) Figure (3-5). Total head losses. Design of Box Culvert 26 Chapter Three Theoretical Background Regardless the type of flow energy losses, the flow losses equation is: 𝑉G ℎ= 𝑘𝑥 … … (𝑒𝑞. 3 − 3) 2𝑔 So, the total head losses can be reformatted as: 𝑉G 𝑉G 𝑉G DH = 𝑘9 + 𝑘2$3&' + 𝑘#C'3&' 2𝑔 2𝑔 2𝑔 DH = (𝑘9 + 𝑘2$3&' 𝑉G + 𝑘#C'3&' ) … … (𝑒𝑞. 3 − 4) 2𝑔 Where: 𝑘 = coefficient of losses Hence, the inlet edge is sharp, 𝑘2$3&' = 0.5 and 𝑘#C'3&' = 1 In order to determine 𝑘9 , the connected canal to the box culvert is an open channel, so, Manning eq. is used to determine the velocity of the flowing water. 𝑉= G O 1 𝑥 𝑅 0 𝑥 𝑆 G … … (𝑒𝑞. 3 − 5) 𝑛 Where: 𝑛 = Manning coefficient of roughness 𝑅 = the hydraulic Radius 𝑆 = the slope of energy line Figure (3-6). Cross section of box culvert. P R is can be found from the culvert cross section, 𝑅 = 𝑅= S is the slope of energy line, 𝑆 = Design of Box Culvert WX Y Q = RS TR 𝐷 … … (𝑒𝑞. 3 − 6) 4 … … (𝑒𝑞. 3 − 7) 27 Chapter Three Theoretical Background Therefore, 𝑉= 1 𝐷 G ℎ9 O 𝑥 ( )0 𝑥 ( )G … … (𝑒𝑞. 3 − 8) 𝑛 4 𝐿 G 1 𝐷 0 ℎ9 \.] 𝑉 = 𝑥 G 𝑥 \.] 𝑛 𝐿 40 G ℎ9 \.] = 𝑉 𝑥 𝑛 𝑥 40 𝑥 𝐿\.] G 𝐷0 … … (𝑏𝑦 𝑠𝑞𝑢𝑖𝑟𝑖𝑛𝑔 𝑏𝑜𝑡ℎ 𝑠𝑖𝑑𝑒𝑠) G ℎ9 = ℎ9 = 𝑉 G 𝑥 𝑛G 𝑥 40 𝑥 6.35 𝐿 T ……∗ 𝐷0 12.7 𝑥 𝑛G 𝑥 𝑔 𝑥 𝑙 T 𝐷0 2𝑔 2𝑔 𝑉G 𝑥 … … (𝑒𝑞. 3 − 9) 2𝑔 From comparing (𝑒𝑞. 3 − 9) to the friction losses eq. j ℎ9 = 𝑘9 𝑥 kS Gl m, It can be noticed that, 𝑘9 = 12.7 𝑥 𝑛G 𝑥 𝑔 𝑥 𝑙 T 𝐷0 … … (𝑒𝑞. 3 − 10) Sub (𝑒𝑞. 3 − 10) in (𝑒𝑞. 3 − 4) DH = n 12.7 𝑥 𝑛G 𝑥 𝑔 𝑥 𝑙 T 𝐷0 Design of Box Culvert + 𝑘2$3&' 𝑉G + 𝑘#C'3&' o … … (𝑒𝑞. 3 − 11) 2𝑔 28 Chapter Three Theoretical Background From the discharge equation, 𝑄 = 𝐴𝑉 𝑉= 𝑄 𝐴 𝑄G 𝑉 = G 𝐴 G 𝑄G 𝑉 = T … … (𝑒𝑞. 3 − 12) 𝐷 G Thus, the equation for case 4 would be DH = n 12.7 𝑥 𝑛G 𝑥 𝑔 𝑥 𝑙 T 𝐷0 + 𝑘2$3&' 𝑄G 1 + 𝑘#C'3&' o 𝑥 T 𝑥 … … (𝑒𝑞. 3 − 13) 𝐷 2𝑔 3-5 Structural design cases The design is carried out for 1m length of the box culvert and based on the obtained dimensions from the hydraulic design. Mainly, the load cases for box culvert design are: 1. Box empty, live load surcharge on top slab of box and superimposed surcharge load on earth fill. 2. Box inside full with water, live load surcharge on top slab and superimposed surcharge load on earth fill. 3. Box inside full with water, no live load surcharge on top slab and superimposed surcharge on earth fill. Oyenuga (2001) proven that the first load case gives the higher value of moments, because when the box culvert inside full with water, the resultant force of hydrostatic water pressure on the inside and resultant of superimposed surcharge load on the outside, the sum of the two resultants yields a lesser resultant force acting on the culvert wall. Therefore, the design will be carried for case 1. Design of Box Culvert 29 Chapter Four Results and Discussion Chapter Four Results and Discussion Chapter Four Results and Discussion 4-1 Hydraulic Design The culvert equation shown below and the obtained field data – from Chapter Three - will be used for the hydraulics design of the box culvert. DH = $ 12.7 𝑥 𝑛+ 𝑥 𝑔 𝑥 𝑙 / 𝐷0 + 𝑘34567 𝑄+ 1 + 𝑘897567 : 𝑥 / 𝑥 … … (𝑒𝑞. 3 − 13) 𝐷 2𝑔 Assume: • Culvert invert level is equal to the main drain (MD-A) bed level. • Length of culvert = 27 m. Figure (4-1). Main drain (MD-A) cross section. Figure (4-2). Culvert side view [invert level = main drain (MD-A) level]. Design of Box Culvert 30 Chapter Four Results and Discussion v First attempt DH = U/S W.L – D/S W.L DH = 8.56 – 8.51 DH = 0.05 m 0.05 = $ 12.7 𝑥 (0.015)+ 𝑥 9.81 𝑥 27 / 𝐷0 1.95+ 1 + 0.5 + 1: 𝑥 𝑥 𝐷/ 2𝑥9.81 By using trial and error D = 1.65 m To ensure the flow conveyance of the culvert is case 4; J.+K J.LK G H ≥ 1.2 = 0.75 < 1.2 Which means the inlet will not be submerged because the value of the headwater (H) is less than the critical value (H`) which is indicated by the relation – 1.2D ≤ H` ≤ 1.5D – where (D) is culvert height, while the outlet will not be submerged neither. In this situation, an invert with a slope of 5:1 must be used to solve this issue. Figure (4-3) Culvert side view when H<H’. Design of Box Culvert 31 Chapter Four Results and Discussion To calculate the required invert: Hcal = 1.2 x D Hcal= 1.2 x 1.65 Hcal = 1.98 m Invert = Hcal. – Hact Invert = 1.98 – 1.25 Invert = 0.73 m Invert with 0.73 m length is hard to execute because the main drain (MD-A) level is already below the ground, so to reach the invert level (I.L), excavation would be very hard to achieve. Thus, the culvert is divided into two boxes, each takes half of the discharge. Figure (4-4). Culvert side view with 0.73 m length invert. Design of Box Culvert 32 Chapter Four Results and Discussion v Second attempt The design for a single box culvert: 𝑄= 1.95 = 0.975 𝑚0/𝑠 2 0.05 = $ 12.7 𝑥 (0.015)+ 𝑥 9.81 𝑥 27 / 𝐷0 0.975+ 1 + 0.5 + 1: 𝑥 𝑥 𝐷/ 2𝑥9.81 By using trial and error D = 1.2 m For case 4, J.+K J.+ G H ≥ 1.2 = 1.04 < 1.2; the headwater (H) is less than the critical value (H`). Figure (4-5). Culvert side view of a single box when H < H`. Design of Box Culvert 33 Chapter Four Results and Discussion To calculate the required invert: Hcal = 1.2 x D Hcal = 1.2 * 1.2 Hcal = 1.44 m Invert = Hcal. – Hact Invert = 1.44 – 1.25 Invert = 0.2 m; which can be considered to be executable. For case 4, GR34S6T7 H ≥ 1.2 1.25 + 0.2 = 1.2 ∴ 𝑜𝑘 1.2 Invert level = main drain (MD-A) level – Invert length = 7.31 – 0.2 = 7.11 m Top culvert level = Invert level + D = 7.11 + 1.2 = 8.31 m Figure (4-6). Culvert side view with 0.2 m length invert. Design of Box Culvert 34 Chapter Four Results and Discussion According to the Design Manual for Irrigation and Drainage by Pencol Engineering Consultants (1983), the thicknesses of the box culvert were assumed to be based on table (11.5), as showing below. The total discharge of the main drain (MD-A) is 1.95 𝑚0 /𝑠. So, the assumed design thickness for top slab, walls and bottom slab is 0.25 m. For checking the assumption of culvert length; Bottom level of road = top culvert level + top slab thickness 8.31 + 0.25 = 8.56 m Height of road = 12.99 - 8.56 = 4.43 m L = Top width of road + (Height of road x Horizontal slope of road) L = 10 + [(4.43 x 2) x 2] = 27 m The calculated length is equal to the assumed length = 27 m ∴ 𝑜𝑘 Design of Box Culvert 35 Chapter Four Results and Discussion Figure (4-7). Section A-A. The velocity (V) of a single box must be, less than 1.5 m/s to prevent corrosion of the unfilled cannel and more than 0.5 m/s to prevent sedimentation of water sediments. To check for the flow velocity (V) of a single box: 𝑄 = 𝑉𝐴 𝑄 𝐴 0.975 𝑉= (1.2)+ 𝑉= 𝑉 = 0.67 m/s ∴ 𝑜𝑘 Design of Box Culvert 36 Chapter Four Results and Discussion 4-2 Structural Design v Loads Loads were calculated and factored according to AASHTO LRFD Bridge Design Specifications 4th Edition (2007). Distribution of wheel live load is neglected due to the article: “For single-span culverts, the effects of live load may be neglected where the depth of fill is more than 2400 mm and exceeds the span length; for multiple span culverts, the effects may be neglected where the depth of fill exceeds the distance between faces of end walls.”. – article (3.6.1.2.6) Since the designed box culvert is multiple span; Fill depth = 4.43m > distance between end walls faces = 2.65m Therefore, distribution of wheel load is neglected. Load factors are obtained from table 3.4.1-2 of AASHTO LRFD, as showing below. Design of Box Culvert 37 Chapter Four Results and Discussion Ø Top slab: 𝑆𝑒𝑙𝑓 − 𝑤𝑒𝑖𝑔ℎ𝑡 = 24 𝑥 0.25 = 6 𝐾𝑁 ⁄𝑚+⁄𝑚 𝐵𝑎𝑐𝑘𝑓𝑖𝑙𝑙 𝑙𝑜𝑎𝑑 = 4.43 𝑥 18 = 79.74 𝐾𝑁 ⁄𝑚+⁄𝑚 𝐹𝑎𝑐𝑡𝑜𝑟𝑒𝑑 𝑡𝑜𝑡𝑎𝑙 𝑙𝑜𝑎𝑑 = 6 𝑥 1.25 + 79.74 𝑥 1.35 = 115.15 𝐾𝑁 ⁄𝑚+⁄𝑚 Ø Exterior side walls: To calculate lateral earth pressure (EH), Mohr’s equation is used to calculate Ka. ∅ 30 1 l = 𝑡𝑎𝑛+ j45 − l= 2 2 3 1 𝐸G = 𝐾i 𝑥 𝛾o 𝑥 𝐻 = 𝑥 18 𝑥 1.45 = 8.7 𝐾𝑁 ⁄𝑚+⁄𝑚 3 𝐾i = 𝑡𝑎𝑛+ j45 − “Where a uniform surcharge is present, a constant horizontal earth pressure shall be added to the basic earth pressure. This constant earth pressure may be taken as: ∆𝑝 = 𝑘o 𝑞o (3.11.6.1-1) Where: ∆𝑝 = Constant horizontal earth pressure due to uniform surcharge (KPa). 𝑘o = coefficient of earth pressure due to surcharge. For active earth pressure conditions, ks shall be taken as ka. 𝑞o = uniform surcharge applied to the upper surface of the active earth wedge (KPa)”. – article (3.11.6) 1 𝑥 79.74 = 26.58 𝐾𝑁 ⁄𝑚+⁄𝑚 3 𝐹𝑎𝑐𝑡𝑜𝑟𝑒𝑑 𝐸G )s8778t = (26.58 + 8.7) 𝑥 1.5 = 52.92 𝐾𝑁 ⁄𝑚+⁄𝑚 ∆𝑝 = 𝐹𝑎𝑐𝑡𝑜𝑟𝑒𝑑 𝐸G )78u = 26.58 𝑥 1.5 = 39.87 𝐾𝑁 ⁄𝑚+⁄𝑚 Design of Box Culvert 38 Chapter Four Results and Discussion Ø Bottom slab: 𝐹𝑎𝑐𝑡𝑜𝑟𝑒𝑑 𝑆𝑒𝑙𝑓 − 𝑤𝑒𝑖𝑔ℎ𝑡 𝑜𝑓 𝑤𝑎𝑙𝑙𝑠 = 3 𝑥 24 𝑥 1.2 𝑥 0.25 𝑥 1.25 3.15 = 8.57 𝐾𝑁 ⁄𝑚+⁄𝑚 𝐹𝑎𝑐𝑡𝑜𝑟𝑒𝑑 𝑙𝑜𝑎𝑑 𝑓𝑟𝑜𝑚 𝑡𝑜𝑝 𝑠𝑙𝑎𝑏 = 115.15 𝐾𝑁 ⁄𝑚+⁄𝑚 𝑇𝑜𝑡𝑡𝑎𝑙 𝑙𝑜𝑎𝑑𝑠 = 115.15 + 8.57 = 123.72 𝐾𝑁 ⁄𝑚+⁄𝑚 The calculated loads can be considered as linear loads since the designed is carried for 1m length of the box culvert. Figure (4-8). Factored load distribution. Design of Box Culvert 39 Chapter Four Results and Discussion Table (4-1). Summary of factored distributed loads. Member Top Slab Load source Load factor Area load (kN/m2/m) Self-weight 1.25 7.5 Backfill 1.35 Total linear load (kN/m2/m) 115.15 115.15 107.65 Top Exterior Lateral side earth walls pressure Total area load (kN/m2/m) 39.87 1.5 Bottom Self-weight of walls 52.92 1.25 8.57 Bottom slab 123.72 Total top slab loads Design of Box Culvert - 123.72 115.15 40 Chapter Four Results and Discussion v Reinforced concrete design Moment calculated according to Building Code Requirements for Structural Concrete (ACI 318M-14) and Commentary (ACI 318RM-14). Figure (4-9). Frame of box culvert. o Fixed end moment (F.E.M.) 𝑤𝑙+ 𝐹. 𝐸. 𝑀.@z{ = 𝐹. 𝐸. 𝑀.@{z = 𝐹. 𝐸. 𝑀.@{| = 𝐹. 𝐸. 𝑀.@|{ = 12 115.15 𝑥 (1.45)+ = = 20.18 𝐾𝑁. 𝑚/𝑚 12 𝑤𝑙+ 𝐹. 𝐸. 𝑀.@H} = 𝐹. 𝐸. 𝑀.@}H = 𝐹. 𝐸. 𝑀.@}~ = 𝐹. 𝐸. 𝑀.@~} = 12 123.72 𝑥 (1.45)+ = = 21.67 𝐾𝑁. 𝑚/𝑚 12 𝑊J 𝑙+ (𝑊+ − 𝑊J )𝑙+ 𝐹. 𝐸. 𝑀.@zH = 𝐹. 𝐸. 𝑀.@|} = + 12 30 39.87 𝑥 (1.45)+ (52.92 − 39.87)𝑥 (1.45)+ = + = 8.11 𝐾𝑁. 𝑚/𝑚 12 30 Design of Box Culvert 41 Chapter Four Results and Discussion 𝑊J𝑙+ (𝑊+ − 𝑊J )𝑙+ 𝐹. 𝐸. 𝑀.@Hz = 𝐹. 𝐸. 𝑀.@~| = + 12 20 39.87 𝑥 (1.45)+ (52.92 − 39.87)𝑥 (1.45)+ = + = 8.67 𝐾𝑁. 𝑚/𝑚 12 20 𝐹. 𝐸. 𝑀.@{} = 𝐹. 𝐸. 𝑀.@}{ = 0 o Distribution factor 4𝐸𝐼 𝑙 𝐾𝐾@ t6ts6T = Σ𝐾@ t6ts6T 𝐾@ t6ts6T = 𝐾@ •8347 Since, all members have the same modules of elasticity (E) and the dimensions are equal which makes the moment of inertia equal for all. Hence, the distribution factor for all joints is equal. 𝐾@ •8347 = 0.5 Design of Box Culvert 42 Chapter Four Results and Discussion o Moment distribution calculation Table (4-2). Moment distribution table. Design of Box Culvert 43 Chapter Four Results and Discussion o Mid-span moments R 𝑀z{ = R 𝑀{| 𝑤𝑙+ 𝑀Jƒ + 𝑀+ƒ = − j l 8 2 115.15 𝑥 (1.45)+ 11.99 + 24.08 = −j l = +12.2 𝐾𝑁. 𝑚/𝑚 8 2 R 𝑀H} = R 𝑀}~ 𝑤𝑙+ 𝑀Jƒ + 𝑀+ƒ = − j l 8 2 123.72 𝑥 (1.45)+ 13.07 + 25.77 = −j l 8 2 = +13.1 𝐾𝑁. 𝑚/𝑚 R 𝑀zH = R 𝑀|~ 𝑤+ 𝑙+ 𝑀Jƒ + 𝑀+ƒ == „ + [0.128 𝑥 (𝑤+ − 𝑤J )𝑥 𝑙] ‡ − j l 8 2 39.87 𝑥 (1.45)+ 11.99 + 13.07 = ˆ + [0.128 𝑥 (52.92 − 39.87) 𝑥 1.45]‰ − j l 8 2 = +0.37 𝐾𝑁. 𝑚/𝑚 R 𝑀{} = 0 o Negative moments at face of support “For slabs built integrally with supports, Mu at the support shall be permitted to be calculated at the face of support”. Design of Box Culvert – ACI 7.4.2.1 44 Chapter Four Results and Discussion 𝑉 𝑥 𝑏 𝑤𝑙 (0.5𝑏)+ = 𝑀 − + ; 2 2 𝑤𝑙 𝑀J + 𝑀+ 𝑉= ± j l 2 𝑙 ƒ 𝑀@o9uu8T7 Ši‹6 ƒ Where; 𝑀ƒ = negative moment at the center of support. 𝑉 = modified shear value due to the difference of negative moments. 𝑏 = width of support. 𝑀J & 𝑀+ = moments of a member’s supports based on the sum of moment distribution table. Table (4-3). Negative moment at face of support. Member AB BC DE EF AD CF Joint A B B C D E E F A D C F Design of Box Culvert 𝑴ƒ 11.99 24.08 24.08 11.99 13.07 25.77 25.77 -13.07 11.99 13.07 11.99 13.07 𝑽𝒖 @𝒔𝒖𝒑𝒑𝒐𝒓𝒕 𝒇𝒂𝒄𝒆 75.15 91.81 91.81 75.15 80.94 98.46 98.46 80.94 31.31 35.96 31.31 35.96 𝑴ƒ @𝒔𝒖𝒑𝒑𝒐𝒓𝒕 𝒇𝒂𝒄𝒆 -3.50 -13.50 -13.50 -3.50 -3.92 -14.86 -14.86 -3.92 -8.43 -8.96 -8.43 -8.96 45 Chapter Four Results and Discussion o Moments summary Table (4-4). Moments summary. Member Joint AB = BC DE = EF AD = CF moment (KN.m/m) A=C -3.5 B -13.5 D=F -3.92 E -14.86 A=C -8.43 D=F -9.05 (KN.m/m) +12.2 +13.1 +0.37 B BE = EB Mid – Span Support moment 0 E o Shear checking “For slabs built integrally with supports, Vu at the support shall be permitted to be calculated at the face of support”. – ACI 7.4.3.1 ›𝑽𝒖 @𝒔𝒖𝒑𝒑𝒐𝒓𝒕 𝒇𝒂𝒄𝒆 œ are obtained from table (4-3). Table (4-5). Vu at the face of support. Member AB = AC DE = EF AD = CF Joint A=C B D=F E A=C D=F 𝑽𝒖 @𝒔𝒖𝒑𝒑𝒐𝒓𝒕 𝒇𝒂𝒄𝒆 𝑲𝑵/𝒎 75.15 91.81 80.94 98.46 31.31 35.96 Design of Box Culvert 46 Chapter Four Results and Discussion “Sections between the face of support and a critical section located d from the face of support for nonprestressed slabs or h/2 from the face of support for prestressed slabs shall be permitted to be designed for Vu at that critical section if (a) through (c) are satisfied: (a) Support reaction, in direction of applied shear, intro-duces compression into the end region of the slab. (b) Loads are applied at or near the top surface of the slab. (c) No concentrated load occurs between the face of support and critical section.” – ACI 7.4.3.2 Hence, (a) through (c) are satisfied, Vu shall be calculated at the critical section which is at distance equal to (d) from the face of support. Concrete cover shall be taken as 75mm for all member because the structure is exposed to ground permanently as specified in (ACI – Table 20.6.1.3.1). ∅siT 2 12 = 250 − 75 − = 169 𝑚𝑚 2 𝑑 = ℎ − 𝑐𝑜𝑣𝑒𝑟 − 𝑉9 @¡ ŠT8t o9uu8T7 Ši‹6 = 𝑉9 @o9uu8T7 Ši‹6 − 𝑤9 𝑑 Table (4-6). Vu at distance d from support face. Member Joint 𝑽𝒖 @𝒅 𝒇𝒓𝒐𝒎 𝒔𝒖𝒑𝒑𝒐𝒓𝒕 𝒇𝒂𝒄𝒆 𝑲𝑵/𝒎 AB = AC A B 55.68 72.35 DE = EF D E 60.03 77.55 AD = CF A D 24.57 33.75 Max 𝑉9 is at joint E = 77.55 KN/m Design of Box Culvert 47 Chapter Four Results and Discussion Checking the shear capacity of the concrete cross section: - 𝑉4 = 0.17𝜆¤𝑓‹` 𝑏¦ 𝑑 𝐴𝐶𝐼 (22.5.5.1) Where: 𝜆 = modification factor according to the type of concrete. In case of normal concrete, it equals 1 as specified in (ACI – Table 19.2.4.2). 𝑓‹` = concrete compressive strength. 𝑏¦ = width of the concrete section 𝑉4 = 0.17 𝑥 1 𝑥 √25 𝑥 1000 𝑥 169 𝑥 10ƒ0 = 143.65 𝐾𝑁/𝑚 The reduction factor (∅) for shear is specified as 0.75 in (ACI – Table 21.2.1). ∅𝑉‹ = 0.75𝑉4 = 0.75 𝑥 143.65 = 107.74 𝐾𝑁/𝑚 ∅𝑉‹ = 107.74 > 𝑉9 = 77.55 ∴ 𝑜𝑘 o Flexural reinforcement The following procedure is obtained from ACI (Chapter 22 – Sectional Strength). 𝑅9 = 𝑀9 , ∅𝑏𝑑 + 𝑚= 𝑓¬ 0.85 𝑓‹` 𝜌= 1 2𝑅9 𝑚 ®1 − ¯1 − ° 𝑚 𝑓¬ ∅ = 0.9 𝐴o = 𝜌𝑏𝑑 Design of Box Culvert 48 Chapter Four Results and Discussion Table (4-7). Reinforcement calculations. Member Joint A=C Mid-Span B D=F Mid-Span E A=C Mid-Span D AB = BC DE = EF AD = CD 𝑴𝒖 𝑹𝒖 (𝑲𝑵. 𝒎/𝒎) (𝑴𝑷𝒂/𝒎) -3.50 12.20 -13.50 -3.92 13.10 -14.86 -8.43 0.37 -9.05 1.39E-01 4.86E-01 5.38E-01 1.56E-01 5.22E-01 5.92E-01 3.36E-01 1.47E-02 3.61E-01 𝒎 𝝆 𝒄𝒂𝒍𝒄𝒖𝒍𝒂𝒕𝒆𝒅 19.76 19.76 19.76 19.76 19.76 19.76 19.76 19.76 19.76 3.331E-04 1.171E-03 1.297E-03 3.732E-04 1.258E-03 1.430E-03 8.061E-04 3.511E-05 8.659E-04 It’s clear that the value of 𝜌 is very small due to the small value of the applied moment (𝑀9 ). Therefore, 𝐴o t34 specified by (ACI – Table 7.6.1.1) must be used. 𝐴o t34 = 0.0018𝑥420 𝐴µ ≥ 0.0014𝐴µ 𝑓¬ 𝐴o t34 = 0.0018𝑥420 (1000 ∗ 250) ≥ 0.0014𝐴µ 420 𝐴o t34 = 450 ≥ 350 + 𝐴o t34 = 450 𝑚𝑚 ·𝑚 𝑀𝑎𝑥 𝑠𝑝𝑎𝑐𝑖𝑛𝑔 (𝑆ti¸ ) = 3ℎ ≤ 450𝑚𝑚 – 𝐴𝐶𝐼 (7.7.2.3) = 3𝑥250 ≤ 450𝑚𝑚 = 750 ≤ 450𝑚𝑚 𝑆ti¸ = 450 𝑚𝑚⁄𝑚 + Use ∅12 @ 250 𝑚𝑚 𝐶·𝐶 , which will provide 𝐴o = 482 𝑚𝑚 ·𝑚 > 𝐴o t34 Therefore, the reinforcement for flexural is, ∅12 @ 250 𝑚𝑚 𝐶·𝐶 Design of Box Culvert 49 Chapter Four Results and Discussion o Shrinkage and temperature reinforcement The required area of steel for shrinkage and temperature is specified by (ACI – Table 24.4.3.2) as: 𝐴o t34 = 0.0018𝑥420 𝐴𝑔 ≥ 0.0014𝐴𝑔 𝑓¬ Which is equal to the flexural area of steel. Therefore: + 𝐴o t34 = 450 𝑚𝑚 ·𝑚 𝑀𝑎𝑥 𝑠𝑝𝑎𝑐𝑖𝑛𝑔 (𝑆ti¸ ) = 5ℎ ≤ 450𝑚𝑚 – 𝐴𝐶𝐼 (7.7.6.2.1) = 5𝑥250 ≤ 450𝑚𝑚 = 1250 ≤ 450𝑚𝑚 𝑆ti¸ = 450 𝑚𝑚⁄𝑚 + Use ∅12 @ 250 𝑚𝑚 𝐶·𝐶 , which will provide 𝐴o = 482 𝑚𝑚 ·𝑚 > 𝐴o t34 Therefore, the reinforcement for shrinkage and temperature is, ∅12 @ 250 𝑚𝑚 Design of Box Culvert 50 Chapter Four Results and Discussion v Analysis using ETABS software One of the main objectives of selecting a numerical model is to reduce the infinite degrees of freedom system to a limited degree of freedom, which will represent the significant physical behavior of the system. The theoretical study presented in this chapter consists of idealization of the physical system under consideration to make it amenable to treat numerically followed by selection of proper numerical technique and mathematical formulation of the specific problems. The box culvert was analyzed using ETABS software and the obtained results are as following: Table (4-8). ETABS results. Reinforcement/𝒎 Walls Top slab Floor slab Flexural Shrinkage and temperature ∅𝟏𝟔 @ 𝟑𝟎𝟎 mm (EF/V) ∅𝟏𝟐 @ 𝟐𝟓𝟎 𝒎𝒎 ∅𝟏𝟐 @ 𝟐𝟓𝟎 𝒎𝒎 ∅𝟏𝟐 @ 𝟐𝟓𝟎 𝒎𝒎 (EF/H) ∅𝟏𝟐 @ 𝟐𝟓𝟎 𝒎𝒎 ∅𝟏𝟐 @ 𝟐𝟓𝟎 𝒎𝒎 Therefore, the obtained results resemble the calculated results. The results in table (4-8) is used as the designed reinforcement. Design of Box Culvert 51 Chapter Four Results and Discussion 4-3 Reinforcement Details Figure (4-10). Typical slab reinforcement. Figure (4-11). Section A-A reinforcement details. Design of Box Culvert 52 Chapter Five Conclusions and Recommendations Chapter Five Conclusions & Recommendations Chapter Five Conclusions & Recommendations 5-1 Conclusions The dimensions of box culvert were obtained from the hydraulic design. The box culvert designed as a two cells culvert with a total length of 27 m and total width of 3.15 m. The span for each cell is 1.2 m measured from face of the supports. The invert of the box culvert is 0.2m downward from the bottom of the main drain (MD-A). Conveyance condition case 4 gave the minimum head losses as required. The box culvert structural elements are top slab, floor slab, two exterior side walls and one interior wall. The box culvert structural design carried out for the maximum bending moment and shear force in each structural element. The design was analyzed by ETABS software which gave a resemble results to the hand calculated results. The used reinforcements are: ¨ ∅16 @ 300 𝑚𝑚 𝐶*𝐶 (𝐸𝐹 ⁄𝑉 ) 𝑎𝑛𝑑 ∅12 @ 250 𝑚𝑚 𝐶*𝐶 (𝐸𝐹 ⁄𝐻 ) for the walls. ¨ ∅12 @ 250 𝑚𝑚 𝐶*𝐶 𝑎𝑡 𝑡𝑜𝑝 𝑎𝑛𝑑 𝑏𝑜𝑡𝑡𝑜𝑚 for top and floor slabs. 5-2 Recommendations For inlet and outlet transition, the suggestion is to use rocks as a transition for both the inlet and outlet due to the ease of execution. However, a suitable design is recommended for choosing the adequate transition. Using ETABS software for the design is helpful and saves a lot of time. However, results must be checked for some criteria such as the minimum reinforcement ratio (𝜌<=> ) which is specified by the design code. Design of Box Culvert 53 References References 1. American Association of State Highway and Transportation Officials, (2007). “AASHTO LRFD Bridge Design Specifications SI Units 4th Edition”. American Association of State Highway and Transportation Officials, 444 North Capitol Street, New York. Pp 1590. 2. American Concrete Institute, (2014). “Building Code Requirements for Structural Concrete (ACI318M-14) and Commentary (ACI 318RM-14)”. American Concrete Institute, P.O. Box 9094, Farmington Hills, Michigan. PP 519. 3. Bolden, J., Carroll, T., Muller, D., Snoke, D., (2016). “Structural Management Unit Manual”. North Carolina Department of Transportation (NCDOT), North Carolina. PP 180. 4. Chandrakant, L. A. and Malgonda, P. V. (2014), “Finite element analysis of box culvert”, International Journal of Advanced Technology in Engineering and Science, Volume No.02, Issue No. 06. 5. Civil Engineering Portal, (2012). “What are the differences in applications between pipe culverts and box culverts?”, URL: http://www.engineeringcivil.com/what-are-the-differences-in-applicationsbetween-pipe-culverts-and-box-culverts.html, Last visit was on 4/11/2017. 6. Creamer, P. A., (2007). “Culvert Hydraulics: Basic Principle”, Professional Development Series (PDF), CONTECH Bridge Solutions Inc., Ohio. Design of Box Culvert 7. Garg, A. K., (2007). “Experimental and Finite Element Based Investigations of Shear Behavior of Reinforced Concrete Box Culverts”, PhD Dissertation, Department of Civil Engineering, The University of Texas at Arlington. 8. Kailan, A. L. (2015). “Hydraulic structures”, Water Resources Engineering lectures, Chapter 5, Department of Civil Engineering, Al-Mansour University College, Iraq. 9. Kilgore, R. T., Morris, J. L., Schall, J. D., Thompson, P. L. and Zerges, S. M. (2012). “Hydraulic Design of Highway Culverts Third Edition”. Federal Highway Administration (FHWA), Washington, D.C. PP 326. 10. Kumar, Y. V., Srinivas, C. (2015). “Analysis and Design of Box Culvert by Using Computational Methods”, International Journal of Engineering and Science Research, 5(7): 850-861. 11. Kim, K. and Yoo, C. (2002), “Design loading for deeply buried box culverts”, Highway Research Center Auburn University, Auburn University, Alabama. 12. Oyenuga, V. O. (2001), “Fundamentals of Reinforced Concrete Design”. Agros Limited, Lagos, Nigeria. PP415. 13. Pencol Engineering Consultants. (1983). “Design Manual for Irrigation and Drainage”, Ministry of Irrigation, Iraq. PP 530. 14. Wikipedia, The Free Encyclopedia. (2004). “Culverts”, https://en.wikipedia.org/wiki/Culvert, Last visit was on 27/12/2017. Design of Box Culvert URL: Appendix Top slab shear values by ETABS. Top slab bending moments by ETABS. Top slab reinforcement by ETABS. Bottom slab shear values by ETABS. Bottom slab bending moments by ETABS. Bottom slab reinforcement by ETABS. Exterior wall moments by ETABS. Exterior wall shear values by ETABS. 12 @ 250 mm 16 @ 300 mm Typical wall reinforcement by ETABS. Typical wall reinforcement layout by ETABS. 12 @ 250 mm 16 @ 300 mm Section A-A of wall reinforcement. 3d reinforcement cage by ETABS. Box culvert moments by ETABS. Box culvert resultant shear by ETABS. Box culvert displacement value by ETABS. اﻟﺨﻼﺻﺔ ﻋﻨﺪﻣﺎ ﯾﻜﻮن ﻣﻄﻠﻮب ان ﯾﺸﯿﺪ طﺮﯾﻖ ﯾﺘﻘﺎطﻊ ﻣﻊ ﺟﺮﯾﺎن اﻟﻤﯿﺎه ﻓﻲ ﻣﺠﺮى طﺒﯿﻌﻲ او ﻗﻨﺎة ﻣﺎﺋﯿﺔ، ﺗﻜﻮن اﻟﻤﺸﻜﻠﺔ اﻟﺮﺋﯿﺴﯿﺔ ﻓﻲ ﻛﯿﻔﯿﺔ اﻟﺤﻔﺎظ ﻋﻠﻰ ﺟﺮﯾﺎن اﻟﻤﯿﺎه دون أي ﯾﺸﻜﻞ أي ﺧﻄﻮرة ﻋﻠﻰ اﻟﻄﺮﯾﻖ او اﻟﻤﺮﻛﺒﺎت اﻟﻲ ﺗﻤﺮ ﻋﻠﻰ اﻟﻄﺮﯾﻖ ﺑﺴﺒﺐ ارﺗﻔﺎع ﻣﻨﺴﻮب اﻟﻤﯿﺎه ﻋﻨﺪ ﺣﺪوث ﻓﯿﻀﺎن ﻓﻲ ﻣﻮﺳﻢ اﻻﻣﻄﺎر او ﻛﻤﯿﺔ اﻟﺘﺼﺎرﯾﻒ ﻓﻲ اﻟﻘﻨﺎة ﺗﻜﻮن أﻛﺒﺮ ﻣﻦ اﻟﻤﺼﻤﻤﺔ ﻟﺘﺤﻤﻠﮭﺎ .ﻟﮭﺬا اﻟﻐﺮض ،ﯾﺠﺐ ﺗﻨﻔﯿﺬ ﻗﻨﻄﺮة ﻋﻨﺪ ﻣﻜﺎن اﻟﺘﻘﺎطﻊ .اﻟﻘﻨﻄﺮة ھﻲ ﻣﻨﺸﺂ ﻣﺼﻤﻢ ﻟﯿﺴﻤﺢ ﺑﻤﺮور اﻟﻤﯿﺎه ﻣﻦ ﺧﻼﻟﮭﺎ .ﯾﻨﻄﻠﺐ اﻟﺘﺼﻤﯿﻢ دراﺳﺔ ﻣﻦ اﻟﻨﻮاﺣﻲ اﻟﮭﯿﺪروﻟﻮﺟﯿﺔ ،اﻻﻧﺸﺎﺋﯿﺔ وطﺒﯿﻌﺔ اﻷرض. اﻟﻤﻄﻠﻮب ھﻮ ﺗﺼﻤﯿﻢ ﻗﻨﻄﺮة ﺻﻨﺪوﻗﺔ ﻓﻲ ﻣﺸﺮوع ﻛﻮت -ﺑﺘﯿﺮه ﻹرواﺋﻲ ﻋﻨﺪ ﺗﻘﺎطﻊ اﻟﻤﺒﺰل اﻟﺮﺋﯿﺴﻲ )م.ر – أ( ﻣﻊ طﺮﯾﻖ اﻟﺪﺟﯿﻠﻲ اﻟﻤﻌﺒﺪ .اﻟﺘﺼﻤﯿﻢ ﺳﯿﻜﻮن ﻋﻠﻰ اﻷﺳﺲ اﻟﮭﯿﺪروﻟﻮﺟﯿﺔ واﻻﻧﺸﺎﺋﯿﺔ. اﻟﺘﺼﻤﯿﻢ اﻟﮭﯿﺪروﻟﻮﺟﻲ ﺳﯿﻜﻮن ﻋﻠﻰ أﺳﺎس اﻟﻤﻌﻠﻮﻣﺎت اﻟﮭﯿﺪروﻟﻮﺟﯿﺔ اﻟﻤﺴﺘﺤﻠﺔ ﻟﻠﻤﻨﻄﻘﺔ .اﺑﻌﺎد اﻟﻘﻨﻄﺮة اﻟﺼﻨﺪوﻗﯿﺔ ﯾﺘﻢ ﺣﺴﺎﺑﮭﺎ ﻣﻦ ﺧﻼل اﻟﺘﺼﻤﯿﻢ اﻟﮭﯿﺪروﻟﻮﺟﻲ .اﻟﻘﻨﻄﺮة اﻟﺼﻨﺪوﻗﯿﺔ اﻟﺘﻲ ﺗﺼﻢ ﺣﺴﺎﺑﮭﺎ ھﻲ ذات ﺧﻠﯿﺘﯿﻦ ﻣﻊ طﻮل ﻛﻠﻲ ﯾﺴﺎوي ٢٧م وﻋﺮض ﻛﻠﻲ ٣.١٤م. ﯾﻌﺮف اﻟﺘﺼﻤﯿﻢ اﻻﻧﺸﺎﺋﻲ ﻋﻠﻰ اﻧﮫ اﺳﺘﻘﺮارﯾﮫ واﻣﺎن اﻟﻤﻨﺸﺄ ﻣﻦ اﻻﺣﻤﺎل اﻟﻤﺴﻠﻄﺔ .ﺑﻌﺪ اﻟﺘﺼﻤﯿﻢ ﻋﻠﻰ وﻓﻖ اﻗﺼﻰ ﻋﺰم اﻧﺤﺎء وﻗﻮى ﻗﺺ ،ﺗﻢ ﺣﺴﺎب ﺣﺪﯾﺪ اﻟﺘﺴﻠﯿﺢ اﻟﻤﻄﻠﻮب ﺣﯿﺚ ﺳﯿﺴﺘﺨﺪم ق ١٦ﻣﻠﻢ ﻛﻞ ٣٠٠ﻣﻠﻢ م/م )ﻟﻜﻞ وﺟﮫ ﻋﺎﻣﻮدي( و ق ١٢ﻣﻠﻢ ﻛﻞ ٢٥٠ﻣﻠﻢ م/م )ﻟﻜﻞ وﺟﮫ اﻓﻘﻲ( ﻟﻠﺠﺪران و ق ١٢ﻣﻠﻢ م/م ﻓﻲ اﻷﻋﻠﻰ و اﻷﺳﻔﻞ ﻟﻜﻞ ﻣﻦ اﻟﺴﻘﻒ اﻟﻌﻠﻮي و اﻟﺴﻔﻠﻲ. ﺟﻤﮭﻮرﯾﺔ اﻟﻌﺮاق ﻛﻠﯿﺔ اﻟﻤﻨﺼﻮر اﻟﺠﺎﻣﻌﺔ ﻗﺴﻢ اﻟﮭﻨﺪﺳﺔ اﻟﻤﺪﻧﯿﺔ ﻣﺸﺮوع ﺗﺨﺮج اﻟﻌﺎم اﻟﺪراﺳﻲ 2017-2018 ﺗﺼﻤﯿﻢ ﻗﻨﻄﺮة ﺻﻨﺪوﻗﯿﺔ ھﺬا اﻟﻤﺸﺮوع ھﻮ ﺟﺰء ﻣﻦ ﻣﺘﻄﻠﺒﺎت اﻟﺤﺼﻮل ﻋﻠﻰ ﺷﮭﺎدة اﻟﺒﻜﺎﻟﻮرﯾﻮس ﻓﻲ اﻟﮭﻨﺪﺳﺔ اﻟﻤﺪﻧﯿﺔ اﻋﺪاد ﻋﻠﻲ ﻣﮭﺪي ﻣﺤﻤﺪ اﺣﻤﺪ ﻧﺎﻓﻊ ﻣﺤﻤﺪ ﻣﺤﻤﺪ ﻋﺒﺪ اﻷﻣﯿﺮ ﺣﺴﯿﻦ ﻣﻌﺘﺰ ﻧﺬﯾﺮ ﻣﺎﺟﺪ اﺷﺮاف د .ﻋﻼ ﻋﺎدل ﻗﺎﺳﻢ 2018م ﺑﻐﺪاد ھـ 1439 View publication stats