Advantages of Composite Construction

Advantages of Composite Construction With regards to Civil and Structural Engineering, composite construction typically refers to the use of steel and concrete formed together so that the resulting component behaves as a single element. The aim of composite construction is to utilise the best properties of the different materials and to deliver performance that is greater than had the individual components been used together but not unified. In the case of steel and concrete, the best properties would be the tensile capacity of the steel and the compressive capacity of the concrete. (Nethercot, 2004) Composite construction is an effective method of construction and delivers good performance. The methodology for designing composite structures has been researched in great detail. For these reasons, composite construction is a very popular method of construction around the world. In order for the materials to behave as one element, it is necessary for some method of connecting the two materials. A shear connection between two materials will enable composite action between them. (The Institution of Structural Engineers) 2.1.1 Benefits of Composite Construction The benefits of composite construction include speed of construction, performance and value. Steel framing for a structure can be erected quickly and the pre-fabricated steel floor decks can be put in place immediately. When cured, the concrete provides additional stiffness to the structure. Additionally, the concrete encasement protects the steel from buckling, corrosion and fire. Service integration within the channels on the composite decks is another advantage to composite construction. Building quality standards can be adhered to easily by the use of pre-fabricated decks. Excessive deflections can be controlled by cambering the beams or by shoring the metal decks to limit deflection when concrete is poured. 2.1.2 Codes for the Design of Composite Structures The design of composite structures was governed by the British Standards. BS 5950-3-1 dealt with the design of beams whilst slabs were governed by BS 5950-4. Pre-fabricated decking used with composite structures was governed by BS 5950-6. Since the introduction of the Eurocode set of standards for the European Union, the design of composite structures is standardised by Eurocode 4. (BS EN 1994-1-2) (BCSA; TATA Steel; Steel Construction Institute) 2.1.3 The Principle of Composite Action The principle of Composite Action underpins the use of composite materials in construction. It relates to the interaction of two or more separate elements acting together and contributing together rather than separately. By physically connecting them, the strength of the beams and the resistance to bending, shear and torsion are significantly increased. The Principle of Composite Action is best illustrated as an example. The diagrams below shows two uniform concrete beams placed on top of each other and loaded with a uniformly distributed load. Both beams will resist the load independently and there will be relative movement between them. The bending strength will be the sum of the individual beams contribution. If the beams have width w and height h, the bending strength M will be: However, if the two beams are connected rigidly together by shear connectors and the relative movement between them is eliminated, the width remains w whilst the height becomes 2h. The bending strength M will be: This represents a doubling of the bending strength through the use of composite action. This is the principle behind the use of steel beams with reinforced concrete floor decks. The two are connected by shear connectors. The increase in strength due to composite action can be as much as 20%, resulting in lighter and thinner sections. (TATA Steel) Figure : The differences between identical beams when composite action is utilised. The beam on the left is comprised of two concrete beams that are not connected compositely. When loaded, there is relative slip between the beams. The component beams on the right are rigidly connected together by means of shear connectors. When loaded, there is no slip between the beams and the assemblage behaves as one large beam. Image from TATA Steel. 2.2 Composite Floor Deck Slabs Composite floor decks are comprised of either steel beams or concrete embedded steel beams together with a reinforced concrete slab. The profiled steel formwork that supports the concrete floor during casting is of vital importance as it also provides the shear bond to enable the materials to work compositely. The role that the profiled decking plays in fire resistance will be discussed in more detail in Section 3.3. Composite action is achieved between the beams and slab by the use of shear connectors that will be discussed in Section 2.4 in more detail. (Metal Cladding and Roofing Manufacturers Association, 2003) The profiled steel decking used in the construction of composite floor systems contributes significantly to the ease and speed at which the structure is construction. It acts as both the permanent formwork and contributes to the overall requirement of reinforcement. The performance of the steel decking when exposed to fire needs careful consideration and is dealt with in Section 3.2. Additional reinforcement is positioned in the troughs of the decking to ensure adequate performance in fire. Benefits associated with using profiled steel decking are reduced dimensions and weight of the overall structure. They also provide satisfactory performance in the areas of strength and economic constraints during construction. (Michel Crisinel, 2004) 2.2.1 Types of Composite Slabs The classification of composite slabs depends primarily on the geometry of the steel deck profile used. Shallow decks are classified by depths in the range of 120-200mm whilst deep decks are classified by depths in the range of 200-350mm. (Aida Rodera Garcia) The most common composite slab consists of the profiled steel decking and concrete cast in-situ. Once cured the concrete and decking act compositely. Sufficient interaction between the concrete is achieved by a chemical bond and a mechanical bond facilitated by the shape of the decking. In design, it is common to neglect the contribution from the chemical bond as it is unreliable. There are many different types of profiled decking available and contribute to the classification of the slab. (Nawy, 2008) Pre-cast concrete slabs can also be used to form a composite floor deck system. The slabs must be designed specifically so that they can interact with the beam system in place. The composite action in this case can be achieved by welded shear studs and transverse reinforcement across the floor deck. By utilising pre-cast concrete decks, hollow core slabs can be used. These can reduce the weight of the whole building whilst offering similar performance to solid slabs. Pre-Cast slabs are usually covered by a layer of concrete after installation to produce a more finished and aesthetic result. Figure : Examples of Hollow-Core Slabs The final type of composite floor slab is the Slim Floor. This consists of the supporting steel beam being encased in the concrete with the lower flange of the beam supporting the floor. Diagrams depicting the various composite slab types in use today are shown below. Figure 4: Proprietary Slim Floor System Slimdek- TATA Steel Figure 3: Example of Solid Slab with Topping and Encasement cast In-Situ Proprietary Slim Floor System Slimdek- TATA Steel http://ars.els-cdn.com/content/image/1-s2.0-S0143974X99000759-gr5.gif 2.2.2 Design Composite floor decks are comprised of permanent formworks of profiled steel decking. The decking serves to support the concrete during casting and before it has cured sufficiently to support itself. It is important to ensure that after curing sufficient interaction between the concrete and steel has developed so that the assembly behave compositely. The rebar is placed in the steel decking prior to pouring as is a steel mesh that serves to minimise cracking over supports and to increase the fire resistance of the floor deck. Most decks achieve a satisfactory degree of shear connection with the concrete by the presence of embossments and indentations along the profile of the decking. This type of shear connection is known as a shear bond. (Steel Construciton Institute, 1994) The decking also contributes to the stabilisation of the structure against lateral torsional buckling of the steel supporting sections and transfers wind loading forces to the walls and columns. The decking also serves to minimise cracking of the concrete slab during expansion and contraction such as during curing and fire. This will be further discussed in Section 3. (Aida Rodera Garcia) The steel decking is normally in the range of 0.9-1.5mm thick and has a yield strength of 280-350 N/mm2. Higher strength steels may be used if the spans are longer than the norm. Typical spans for a composite floor deck are between 2.7 and 3.6m although longer spans may be achieved by shoring the deck during construction. Galvanisation of the faces of the decking is done to prevent damage to the steel during pouring and in service. 2.2.2.1 Concrete Type Strength Both Normal Weight Concrete (NWC) and Light Weight Concrete (LWC) may be used in composite floor slab construction. The most convenient method for concrete placement is by pump. The concrete type and grade is an important design consideration as it affects the final stiffness of the deck system and the strength of the shear connection. 2.2.2.2 Steel Decking Resistance The elastic moment resistance of the steel decking may be calculated from the effective breadth of the steel elements in compression. Stiffeners are present in the deck design and contribute to increasing the effectiveness of the section. In designing a deck system, moment redistribution is not allowed. This results in an underestimate of the critical load for the decking. (ECCS, 1993) 2.2.2.3 Deflection Deflection limits for a composite slab are generally the span/180. However, by shoring the composite slabs during casting, this can effectively be reduced to zero. Increased deflection limits of span/130 are allowed if pooling of the concrete occurs in the middle of the span after pouring. (ECCS, 1993) 2.2.2.4 Transverse Reinforcement The strength of the concrete should be checked to ensure it is capable of receiving the force transferred from the shear connectors. Where the concrete may be susceptible to cracking, the provision of transverse reinforcement perpendicular to the beam is required. (Aida Rodera Garcia) 2.2.3 Failure The ultimate moment resistance of a composite slab is defined as the point at which less than 2mm of longitudinal slip has occurred between the concrete and the decking. Failure of a composite deck is deemed to have occurred when slip of more than 2mm occurs. Failure most commonly occurs during curing before the concrete has reached its design strength. 2.2.4 Fire Resistance of Composite Sections The minimum slab depth will be determined by the fire insulation requirements and the amount of reinforcement that is necessary to withstand loading at the fire limit state. This will be dealt with in more detail in Chapter 3. 2.3 Composite Beams A composite beam can be structurally described as a T-Beam, with the top flange composed of concrete in compression and the steel section in tension. Forces between the two materials are transferred by shear connectors. The principle of composite action with regards to beams leads to increased strength and stiffness of the system whilst using a smaller steel section. The two main variants of composite beams used today are shown in Figure 6. Beams are usually composed of a UKB or UKC section, partially or fully encased in concrete for strength and fire resistance purposes. (ECCS, 1993) 2.3.1 Design In composite beam design, the steel section is first sized to adequately support all the loads acting on it. No contribution is taken into account from the concrete as it has not gained adequate strength for composite action. A common value for the load applied to the beam from the concrete slab is 0.75kN/m2. Once the loading has been calculated, the beam is designed according to Eurocode 3. The presence of steel decking normal to the steel section provides lateral restraint to the beam. In this case, the beam can reach its full plastic moment. In cases where the presence of steel decking is parallel to the beam, the beam is only laterally restrained at the connections at either end and the buckling resistance of the beam must be calculated based on its effective length. The effective breadth of the concrete flange, taken from the supported slab, is approximated as the span/8 on both sides of the beam. This results in an effective breadth of span/4 for simply supported internal beams. 2.4 Shear Connectors Shear connectors are an essential element of composite construction if it is to perform adequately. The main purpose of the shear connector is to provide longitudinal shear resistance between the materials so that they act compositely and to facilitate the interaction between the different materials and to allow them to act as one. (MCRMA, 2003) The shear connection between steel beams and concrete slabs is typically achieved by headed steel studs, welded to the top flange of the steel beam and subsequently encased in concrete. The performance of the studs depends on their dimensions and the spacing along the flange of the beam. Near supports, where the shear forces are greatest, the spacing is reduced. Shear studs can be welded through steel decking. Welding shear studs to the steel beams has a number of limitations and guidelines. The flange of the steel beam has to be bare and can not contain any contaminants such as intumescient paint used as fire protection or moisture. This method also works best when the thickness of the steel decking is less than 1.25mm. Weather conditions will also affect the use of this method of connection. Excess moisture in the air can result in the finished weld being brittle and prone to sudden failure. Shear connectors can also be placed during production although mistakes in placement can be difficult and costly to correct. The purpose of a shear connector is to primarily resist lateral shear forces and displacement between the beam and concrete slab. However, they are also designed to prevent upward displacement of the slab from the beam as it has a tendency to do. For this reason, the studs are headed to provide vertical resistance to seperation. 2.4.1 Types of Shear Connectors In the past, the most common method of shear connection was a headed stud. As welding is only suitable for decking with a minimum thickness, where the decking is too thin, nailed studs are used instead. The choice of which shear connector is used ultimately depends on the shear resistance required and the grade and strength of concrete used. There are four main types of shear connector in use today. The most common is the headed stud. However, with the advent of thinner composite decks, the use of headed studs is not practical. This had led to the introduction of nailed sheets of shear connectors. The dimensions of the most common stud are 19mm x 125mm and the method of connection to the steel beam is ceramic disk welding. (Aida Rodera Garcia) 2.4.1.1 Headed Studs The most common form of connecting materials compositely is with the use of headed shear studs. The behaviour of headed studs does not vary significantly when concrete properties are changed. Resistance to shear depends on the number of studs used and performance is less that that achieved by more modern shear connectors such as the Perfobondstrip or a welded T-Section. (Zingoni, 2001) The advantages of stud connectors is that the welding process is quick and simple, the placement of the studs does not interfere with the placement of reinforcement within the slab and they provide uniform resistance to shear in all directions normal to the axis of the stud. (Johnson, 2004) 2.4.1.2 Oscillating Perfobondstrip The curved form of an oscillating perfobondstrip provides better force transfer between steel and concrete than a continuous strip. The load capacity of this connector is larger than a headed stud or welded T-Section. This form of connector is most suited to light weight concrete or high strength normal weight concrete. Problems with this form of connection are difficulties in welding the section to the steel beam. (Zingoni, 2001) 2.4.1.3 Continuous Perfobondstrip The continuous perfobondstrip is similar to the oscillating perfobondstrip but achieves lower resistance values in all categories of concrete type and grade used. For this reason it is not as widely used as the oscillating form although welding is easier. 3.3.1.4 Welded T-Section Welded T-Section connectors perform very well in comparison to headed studs and achieve the same load resistance as oscillating perfobondstrip. Load capacity increases when Light Weight Concrete or high strength concrete is used. The strength comparisons of the shear connectors described above are shown in Table 1 below. The results were obtained from Galjaard and Walraven (2001) from tests carried out to Eurocode 4 standards for push-out resistance. It can be seen that large differences in resistance and ductility were observed. (Aida Rodera Garcia) 2.4.2 Shear Connector Design The choice of which shear connector design is open so long as it possesses the ductility and provides the necessary shear and separation resistance to the composite system. Headed studs are the most common form of connection and the design of such will be dealt with in this section. The design of shear connectors and composite slabs is given in Eurocode 4. Partial safety factors (ÃŽÂ ³v) of 1.25 for ultimate, 1.0 for serviceability and 1.0 for fire are specified in the codes. (Steel Construciton Institute, 1994) 2.4.2.1 Spacing The correct placement of studs along the upper flange of the beam is of great importance. It is important that the flange of the beam be clean, dry and free of contaminants such as paint or fire protection material. A number of conditions for the placement of studs are described below. The upper flange thickness may not be less than 40% of the diameter of the headed stud. After pouring, the head of the stud should have a minimum of 20mm cover. The minimum edge spacing of the headed studs is 20mm, to facilitate welding. Transverse spacing of headed studs must be greater than or equal to four times the diameter of the headed stud. Longitudinal spacing of the headed studs must lie between the minimum of five times the diameter of the headed stud and the maximum of 800mm or six times the overall depth of the slab, whichever is smaller. (ECCS, 1993) 2.4.2.2 Resistance of Shear Connectors The failure of a composite floor deck slab and the failure of shear connectors occurs due to either the strength of the concrete being surpassed or the strength of the weld connecting the studs to the flange of the beam failing. Shear connection design resistances are taken as the minimum of either the concrete or the headed stud. The equations for the design resistance of the concrete and the headed stud are given below. Where: d is the diameter of the headed stud. The ultimate tensile strength (fu) is most commonly 450N/mm2 and should not exceed 500N/mm2. The characteristic cylinder strength of the concrete is given by fck. Ec is the mean value of the secant modulus of the concrete. The values for different concrete strengths are given in the Annex Table 4. The value for ÃŽÂ ± is governed by the ratio of the height of the slab to the depth. The values of ÃŽÂ ± are given below. For 3 à ¢Ã¢â‚¬ °Ã‚ ¤ h/d à ¢Ã¢â‚¬ °Ã‚ ¤ 4, ÃŽÂ ± = 0.2(h/d +1) For h/d > 4, ÃŽÂ ± = 1.0 The partial safety factor () given by 1.25 in the ultimate limit state. (ECCS, 1993) Figure 10: Bearing stress on the shaft of a Headed Stud Connector (Johnson, 2004) 2.4.2.3 Degree of Shear Connection The degree of shear connection is based on whether the required numbers of shear connectors necessary for the composite beam to develop its full plastic moment have been installed. If fewer than the required amount necessary have been installed, the moment resistance of the composite system will be less than the maximum. The degree of shear connection is given by the equations below. Where Rc denotes the compressive resistance of the concrete slab and Rs denote the tensile resistance of the steel section. Both values are given by the equations below. Where hc is the depth of the concrete slab above the profiled decking. Eurocode 4 also provides provision for the minimum for the degree of shear connection based on the span (L) of the composite beam. These ratios are given below. For: L à ¢Ã¢â‚¬ °Ã‚ ¤ 5m, N/Nf à ¢Ã¢â‚¬ °Ã‚ ¥ 0.4 5m à ¢Ã¢â‚¬ °Ã‚ ¤ L à ¢Ã¢â‚¬ °Ã‚ ¤ 25m, N/Nf à ¢Ã¢â‚¬ °Ã‚ ¥ 0.25 + 0.03L L > 25m, N/Nf à ¢Ã¢â‚¬ °Ã‚ ¥ 1.0 (ECCS, 1993) Chapter 3 Composite Steel Deck Floors in Fire 3.1 Background The performance of composite steel deck floors in fire has been much studied to assess the design considerations that must be implemented and for designing the rules for reinforcement placement. In general, composites perform well in fire due to the insulating properties of concrete and the role of correctly placed mesh reinforcement and metal decking. (BCSA, Corus, SCI, 2007) Research conducted in the UK has concluded that previous methods of designing composite floor decks for fire scenarios was over conservative and that composite floor performance in many common fire scenarios was satisfactory. (Steel Conctruction Institute, 1991) Composite steel deck floor systems are typically not provided any fire protection material although the supporting beam to which the floor is connected is fire protected. The profiled decking of a composite floor acts as some of the tensile reinforcement of the system. For this reason, it is important to account for the effects that elevated temperatures will have on the decking. (Steel Conctruction Institute, 1991) The main contributor to the fire resistance of a composite slab is the embedded rebar mesh in the slab. As the temperature of the profiled decking increases in a fire scenario, the resistance that it provides is neglected. Additional reinforcement in placed in the slab to compensate for the loss of strength of the decking at elevated temperatures. The embedded reinforcement mesh is insulated by concrete and maintains a temperature sufficient for load bearing at the fire limit state. The positioning of rebar within composite floors typically results in higher concrete cover compared to normal reinforced concrete slabs. This results in good fire performance as the temperature of the reinforcement will rarely approach critical levels. The positioning of the reinforcement in the upper of the slab also contributes to controlling spalling in fire. The decking of a composite does play an important role however in maintaining the integrity of the concrete slab during fire. It limits the passage of flame and hot gases into direct contact with the concrete and controls spalling. 3.2 Load Resistance in Fire Design of composite slabs in fire conditions is based on the ultimate limit state properties. A composite floor slab is assumed to behave in bending as either a simply supported or continuous element. The load resistance of a composite floor deck system is due to the floor behaving as a reinforced concrete slab with loads being resisted by the bending action of the slab. Failure of a slab in fire occurs as a result of reinforcement failure. (Corus Construction Industrial, 2006) 3.2.1 Methodology There are two main methods for calculating the fire resistance efficiency of a composite floor deck system, referred to as the fire engineering method and the simplified method. 3.2.1.1 Fire Engineering Method The fire engineering method is based on the assumption that in the fire limit state, the plastic moment capacity of the floor is reached at higher temperatures and that redistribution of moments occurs where the slab is continuous. Temperature gradient experiments have produced temperature profiles such as those present in the Eurocodes. These profiles can be used to calculate the capacities of the beam in both hogging and sagging bending. The capabilities of the beams in the fire limit state can then be assessed. 3.2.1.2 Simplified Method The simplified method involves little or no calculation and relies on test data of actual fires to design the reinforcement in the composite slab. The density of the mesh can be adjusted to account for point loads and increased moment around supports. In general, the simplified method will deliver a result that demands less reinforcement in the design whilst the fire engineering method will allow greater flexibility in positioning the reinforcement and customising fire resistance time periods. The use of different grades of concrete will affect the dimensions and composition of a composite slab. Light Weight Concrete (LWC) has better insulating properties versus Normal Weight Concrete and its use will result in thinner slabs. 3.2.1.3 Design Period Deflection Limits The fire resistance of a composite floor deck system is measured as the time that a floor system can maintain sufficient load-carrying ability, maintain its integrity or by limiting heat transfer through the slab. The load-carrying ability of the composite floor system is measured by the amount of deflection that the system undergoes during fire exposure. Deflection greater than the span/30 is deemed critical as is a deflection rate greater than span2/9000d mm/min between deflections equalling span/30 and span/20. The integrity of the composite floor is deemed satisfactory for fire resistance if it can limit the passage of flame and hot gases. The insulating properties of concrete are deemed sufficient for fire resistance if after fire exposure, the upper surface temperature of the concrete slab remains below 140 °C. (Steel Conctruction Institute, 1991) 3.2.1.4 Reinforcement Fire resistance of a composite deck is attributed to the positioning of reinforcement in a mesh configuration within the slab. The most common forms of mesh are A142 mesh (6mm wires at 200mm c/c) and A193 mesh (7mm wires at 200mm c/c), the numbers referring to the cross-sectional area of steel per metre run, although larger gauges may be used if necessary. The tensile strength of the reinforcement is typically 450-500N/mm2. The positioning of the mesh is in the upper portion of the slab with a minimum cover and can be arranged to resist hogging or sagging bending or a combination thereof. (Aida Rodera Garcia) 3.3 The Fire Engineering Method The fire engineering method for composite slab design is discussed in this section. The partial safety factors at the fire limit state for materials and loads are outlined below. Materials: Steel: ÃŽÂ ³mr = 1.0 Concrete: ÃŽÂ ³mc = 1.3 Loads: Dead: ÃŽÂ ³fd = 1.0 Imposed ÃŽÂ ³fi = 1.0 3.3.1 Materials In conjunction with a suitable design fire scenario, it is possible to account for the reduction in strength of both the reinforcement and the concrete in fire conditions. With elevated temperatures, a reduction factor K may be used to account for the loss of strength associated with the increase in temperature. The table of reduction factors is given in Annex Table 5. The equations used for assessing the design strengths of the reinforcement and concrete at elevated temperatures including the reduction factor (K) are given below. Reinforcement: Concrete (Steel Conctruction Institute, 1991) 3.3.2 Depth The minimum depth of the concrete slab is taken from the tables below. Different values are obtained depending on the type of decking used, such as trapezoidal or re-entrant, and the concrete grade. This minimum depth satisfies the insulation requirement for composite slabs during fire exposure. Alternatively, the minimum depth may be taken from experimental test results from buildings of a similar design. (Steel Conctruction Institute, 1991) (Aida Rodera Garcia) 3.4 The Simplified Method The simplified method consists of installing a layer of mesh (A142, A193 or similar) in the upper layer of the concrete. One of the main differences between the Fire Engineering Method and the Simplified Method is that relatively few calculations are required for the Simplified. An outline of the Simplified Method is a follows: Imposed loads on a composite floor deck slab should not exceed 6.7kN/m2. The mesh size is chosen based on the required fire resistance period and the span of the slab. The minimum cover to any part of the mesh must be at least 15mm and not greater than 45mm. The span of a composite floor slab designed using the Simplified Method is typically 3.6m although spans greater than this may be used if adequate calculation is carried out. 3.5 Comparison of Methods While no method is definitively better than the other, they both have advantages over the other. The Simplified Method is more economical and is based directly on test results and not on theoretical calculation, which has a tendency to under-estimate the strength of materials. The Simplified Method also takes into account the contribution from the profiled steel deck even though the contribution may be small compared to that from the reinforcement mesh. The Fire Engineering Method however allows great flexibility in the customisation of the reinforcement and fire resistance periods. It is generally more expensive to design using this method as opposed to the Simplified Method though will result in thinner slabs that utilise more reinforcement. 3.6 Shear Connectors in Fire The performance of shear connectors in fire has not been widely studied. One of the major research projects on shear connectors in fire was The Restrained Beam Test conducted by British Steel as part of the Cardington Fire Tests in January 1995. The test consisted of the heating of a secondary beam and an area of the surrounding slab on the seventh-floor of the test structure. The steel section tested was a 305165 UB40 that was heated along 8m of its 9m length. Only the top 70mm of the concrete slab was taken into account. This was the maximum height of the slab above the troughs of the profiled decking. (Huang, Burgess, Plank, 1999) The temperature distributions in the steel beam and concrete slab were taken as averages of the test results recorded across the cross-sections of the components. The temperature of headed studs exposed to fire was approximated as 75% of the temperature reached by the top flange of the steel section. (Huang, Burgess, Plank, 1999) The degree of shear connection in the heated beam was assumed to be partial whilst the rest of the composite floor deck systems in the surrounding area were modelled as having full shear interaction. Analysis of the test results showed that the deflection at the mid-span of the heated beam increased with temperature. It was concluded from this that the assumption that partial interaction was corre

H Report

Table of contents 1. Introduction 2. Macro environmental analysis (PESTLE- political, economic, social, technology, legal, ecological) 3. Customer analysis 4. Market description 5. SWOT analysis (Strengths, weaknesses, opportunity, threats) 6. Conclusion and Recommendations 7. References P. 1 D002 T2242531 Introduction H&M (Hennes & Mauritz) is a global fashion brand and retail clothing company founded in Sweden, 1947 by Erling Persson.H & M founder Erling Persson because of a U. S. tour, inspired him to open a low price, high-class women's fashion clothing store ideas. (â€Å"H;M offers fashion and quality at the best price†, 2011) The first Hennes opened in Vasteras, which is the predecessor of H;M. In 60s, he expanded Hennes in most parts of Sweden, developed new markets in neighboring Norway and Denmark in 1964 and 1967. In order to expand the market share and product lines in Stockholm, Persson acquired a company called Mauritz Widforss, firearms and hunting supply store s to get the men`s clothing usiness for Hennes. After that, Persson renamed as Hennes ; Mauritz and still in use. Until the 21st century, H;M began to expand business in Asia. It has over 2,300 stores in 41 countries and as of 2011 employed around 87,000 people for now. H;M designer collaborations with plenty of famous designers and celebrities, such as Karl Lagerfeld, Roberto Cavalli, Stella McCartney, Comme des Garcons, Viktor ; Rolf, Madonna, Lanvin and Sonia Rykiel. (â€Å"H;M-Wikipedia†, 2011) The report is to analyze about the H;M Company (Hennes; Mauritz).This includes the Marco environmental analysis (PESTLE- political, economic, social, technology, legal, ecological), customer analysis, market description, SWOT analysis (Strengths, weaknesses, opportunity, threats), after that, the conclusion, recommendations and references will be provided. P. 2 D002 T2242531 Environmental Analysis (PESTLE) PESTLE means political, economic, social, technological, legal and environm ental. Political: EU and national laws; codes and practice (David Jobber, 2007, p. 3) H;M Company is following the enactment of Swedish and the actions of Swedish companies, as H;M is a Swedish brand and company. Nevertheless, if there is an H;M store located in Cambodia therefore that H;M store  has to follow the Cambodia government legislation. (â€Å"Worldnews. com†. 2011) For instance, there has an article posted on hm. com about Royal Government of Cambodia is considering amendment to article 67 and 73 of Cambodia enactment. This affects H;M as it injures their short-term contracts.If there are changes in laws, H;M has to change the purposes or operations to fit the requirements. Economic: economic growth; unemployment; interest and exchange rate; global economic trends (David Jobber, 2007, p. 43) H;M Company has over 87,000 employees in about 41 countries for now, they target growth around 10-15 percent new stores per year. (â€Å"H;M offers fashion and quality at th e best price†, 2011) It shows H;M create a large number of Employment opportunities for the sociaty, conducive to economic growth.Social: changes in world population, age distribution and household structure; attitude and lifestyle changes; subcultures within and across national boundaries; consumerism (David Jobber, 2007, p. 43) H;M makes sure all products can meet customer`s anticipation. All products have to go through over 100 quality controllers, to inspect if the quality of the product can meet the quality and safety standard. That guarantees that H;M customers can use H;M products safely.H;M Company supports UNICEF in Uzbekistan to show their social responsibility and tries to prevent child work in cotton factory of Uzbekistan. These projects raise the awareness of the right of the child and give safeguard. H;M is going to donate US$ 150,000 to UNICEF’s work in Uzbekistan. (â€Å"IPS ipsnews. net†, 2011) P. 3 D002 T2242531 Technological: new product and p rocess technologies; new materials (David Jobber, 2007, p. 43)H;M has two types of technology that will affect the business that are media technology and printing machines. In the operation of making clothes some of certain colors and designs need some unusual or more high-class machine to finish therefore H;M can keep the product in a quality. (â€Å"Adpunch. org†, 2010) The evolution of media technology will help H;M become popular through the Internet and advertise. The website and media have to be updated to become more eye-catching and disseminate their news events, it can extend the exposure of H;M to the ommunity. Legal: EU and national laws; codes of practice (David Jobber, 2007, p. 43) H;M Company cares about the protection of child; however so far this year, the collective fainting incident at the plant collapsed the number of employees has more than one thousand five hundred people. The labor department of Cambodia said the reason of this trend is including the use of pesticides, dust, heat, perssure and carry the goods to move goods consuming high physical work, hundreds of workers gathered in the small and closed environment.They believe that part of the plant is really have problem, such as in poorly ventilated conditions using specific chemical agents. Community Legal Education Centre claimed that the lack of further work in Cambodia environmental monitoring system. H;M said the company deeply concerned about the incident and seeking to investigate. (â€Å"International Labour Organization†, 1996-2011) Environmental: global warming; pollution; energy and other scarce resources; environmentally friendly ingredients and components; recycling and non-wasteful packaging (David Jobber, 2007, p. 3) H;M is always caring about the environment, particularly the development of organic cotton. Plenty of people try to invent cotton against nature, for example, produce cotton with chemicals. In order to protect the environment and gain the good image for H;M Company. H;M Company has to follow roles that can protect the environment. (â€Å"H;M offers fashion and quality at the best price†, 2011) P. 4 D002 T2242531 Customer analysisH ; M is â€Å"fast, aggressive, accurate† as the main feature of the rapid rise of fast fashion, driven by global fashion trends. (â€Å"H;M offers fashion and quality at the best price†, 2011) They also describe its mission as â€Å"Fashion and quality at the best price. † H;M is used in â€Å"small, a variety† of product strategy, it breaks the traditional limit apparel industry, in the same season will continue to introduce new models for consumers to choose. H;M`s business scope has men`s, women`s, women`s underwear, children`s clothing and accessories.General characteristics of H;M`s clothes are rich in color choice, style wild simple, dynamic and fashionable, casual, comfortable, affordable, not expensive, therefore the products of H;M are suitable for t he students, young office ladies, travellers. (â€Å"Just-style†, 2011) They have set the target consumers group of young people, who aged around 15-30, this type of fashion buyer groups with a high degree of sensitivity and have some spending power, but do not have the ability to possess the regular consumption of high-class brand`s product. (â€Å"Inspiring customer experience†, 2010)For instance, there is a young woman, who may just graduated or still studying in university or high school. She cannot afford to buy high-class brand clothes, she might consider to buy H;M clothes, because H;M`s clothes are design by large number of famous designers and celebrities. This shows H;M attracts plenty of young girls who have high degree of sensitivity. P. 5 D002 T2242531 Market description Sweden`s H;M Company, full name Hennes ; Mamitz, by founder Erling Persson founded in Sweden in 1947, the clothing retail chain.Currently in Europe and North America 29 countries and regi ons have their retail stores. Annual sales of goods more than 5. 5 million, has become one of the Europe`s largest clothing retail chain. The major rival of H;M is ZARA. Spanish fashion brand ZARA is well known in Spain ranked first, third softball apparel retailer Inditex company`s brand, the company has nearly 2,000 stores worldwide, ZARA is one of nine brands if Inditex, the most famous flagship brand, is considered to be Europe`s most research value of the brand. Tony Hines and Margaret Bruce (2007)The success of both companies benefited from the use of unique marketing strategy. Two companies have taken on in the price of low-coast strategy. ZARA is target the consumer group has high income and high-educated young people, mainly 25-35 year-old customer layers, H;M has set the target consumer group of young people 15-30 years old. Two companies frequently updated fashion cheap products just to meet the needs of this population. H;M take the price lower than ZARA layer of strateg y. According to statistics, H;M fashion price is lower than ZARA about 30% to 50%.Tim Jackson and David Shaw (2009) In price discounts, H;M is using the less discount strategy, because all products of H;M are â€Å"small amount and variety†, for example, consumers who buy the first time, there is a risk of no longer buy, therefore they are often unable to wait until the end of the quarter or the end of the year discount. It is kind of psychological advantage of consumers. Almost all of the goods sold in a short time, leave only a small amount of undesired products at discount end of the quarter or the end of the year.H;M estimated 2005 pre-tax profit of 1. 4 billion, on sales of 6. 3 billion. (David Jobber, 2007,p. 35) P. 6 D002 T2242531 SWOT analysis SWOT means strengths, weaknesses, opportunities and threats. (David Jobber, 2007,p. 46) Strengths The main reason why H;M has become popular is low price. H;M provides good quality clothing, department store price that is extre mely unusual in many of today’s retailers.Another advantage of the H;M is the product delivery time, only less than 13 weeks, a project from the design to retail store, that is quite impressive for a international, low price retailer. (â€Å"Jing`s Marketing Blog†, 2011) In addition, they use guest designer bands and shop to keep the line fresh and special, at an affordable price, ability to reach a large target market to satisfy different fashion tastes, having a well-known brand name. Weaknesses Customers may think clothes to be low quality because of the low price, that is a type of psychological of some customers and the quality of service also is a problem for H;M.A large retail store, if there are only a few numbers of staff, they are unable to take care of all the customers. On the other hand, because the company buys a large number of means, there is no one can promise all the items will be sold out. That means their low price may have to be lower and lower to attract consumers to buy their products or means that H;M Company may have to pay additional storage space for these unsold items. (â€Å"H;M-Facebook†, 2011) Opportunities There will be a good opportunity launch some clothes are for elderly people. They can develop a new line for elderly people.I think it would be a good opportunity for H;M, because elderly people also want to wear fashion clothes with a nice, low price, I also think this opportunity can let H;M become more popular, also make more people aware of this brand H;M. Threat There is more and more new retailers appear in the market, such as ZARA, Forever 21, River island. These retailers undoubtedly formed a kind of competition, each firm also has their own marketing program, own characteristics, and the main threat is they are also using the same marketing strategy as H;M â€Å"good quality at a low price†.H;M has to create some new strategy to strong stay competitive. Tim Jackson and David Shaw (2009) P. 7 D002 T2242531 Conclusion and Recommendation The biggest threat for H;M is other retailers from other countries, they are also have plenty of capital and technology to against H;M, therefore H;M should have some innovation actions and strategies to increase the competitive in the fashion market to maintain and attract more customers.First, rely on H;M`s standardized management capabilities to continuously improve their management level and the quality of products. Second, full play to their favorable factors and development, and vigorously promote the clothing company with foreign strategic cooperation. Third, appropriate under the circumstances of the adjustment value, adjusted by way of sale. References David Jobber (2007) Principles and Practice of marketing 5th Edition Fast fashion. (2011). Retrieved 21 October 2011 from the Wikipedia website: http://en. wikipedia. rg/wiki/Fast_fashion H;M Discussions (2011). Retrieved 1 January 2009 from the Facebook website: http://www. face book. com/board. php? uid=21415640912 H;M readies itself for sourcing challenge (2010) Retrieved 12 June 2010 from the just-style. com website: http://www. just-style. com/analysis/hm-readies-itself-for-sourcing-challenge_id108103. aspx H;M experiments with technology driven campaign (2007) Retrieved 30 August 2007 from the Adpunch. org website: http://www. adpunch. org/entry/hm-experiments-with-technology-driven-campaign/ P. D002 T2242531 H;M-Cotton from Uzbekistan (2011) Retrieved 25 April 2009 from the H;M website: http://about. hm. com/gb/corporateresponsibility/supplychainworkingconditions/supplychainmonitoring/cottonfromuzbekistan__monitoringarticle5. nhtml H;M offers fashion and quality at the best price (2011) Retrieved 25 August 2011 from the H;M official website: http://www. hm. com/gb/ H;M in Cambodia (2004) Retrieved 17 May 2004 from the International Labor Organization website: http://www. lo. org/global/about-the-ilo/press-and-media-centre/videos/video-news-releases/W CMS_074487/lang–en/index. htm Hennes&Mauritz (H&M), AN HRM CASE STUDY (2009) Retrieved 12 September 2009 from the ideas and thoughts website: http://ideasthoughts. erruppackal. com/2009/09/hennes-mauritz-hm-an-hrm-case-study/ Hundreds of workers collapse at Cambodian H&M clothing factory (2011) Retrieved 29 August 2011 from the Worldnews. com website: http://article. wn. com/view/2011/08/29/Hundreds_of_workers_collapse_at_Cambodian_H_M_clothing_facto/Social Media strategies of H;M (2011) Retrieved 15 May 2011 from the Inspiring Customer Experience website: http://patperdue. com/social-media-strategies-of-hm-zara-and-esprit-analysis/ Tony Hines and Margaret Bruce (2007) Fashion marketing second edition Tim Jackson and David Shaw (2009) mastering fashion marketing UZBEKISTAN: Forced child labor kills (2011) Retrieved 19 October 2011 from the IPS ipsnews. net website: http://www. ipsnews. net/news. asp? idnews=105514 4P analysis of H;M (2010) Retrieved 24 October 2010 from the J ing`s Marketing Blog website: http://blogs. ubc. ca/jingwei/2010/10/24/4p-analysis-of-hm/ P. 9

The Public Perception of CPAs in Today’s Society

This paper will discuss the public perception of CPAs in today's society, pitfalls that they may encounter, methods to prevent some of these negative behaviors and consequences they may face should they fall short. Most â€Å"Who Do You Trust? † surveys rank politicians, lawyers and used car salesmen at the bottom and certified public accountants at the top. That is because the CPA profession has a squeaky clean image–anal-retentive little wimps who wear thick glasses and cannot get a date. CPAs are known and respected for their honesty. The profession that goes out of its way to project that image, and there is a certain amount of truth to it. Not all accountants are anal-retentive little wimps who cannot get a date. Many of them are quite articulate. Some are quite lovely, in some schools, more than half of the accounting majors are women. Also, not all CPAs are squeaky clean and respected for their honesty. Some are quite dishonest and are putting a black mark on the image of the entire profession. There is one area where the CPA profession has fallen short of protecting the public interest. The general duty that accountants owe to their clients and the other persons who are affected by their actions is to â€Å"exercise the skill and care of the ordinarily prudent accountant† in the same circumstances. Two elements compose the general duty of performance: skill and care. Another element and responsibility is owed to clients and other persons, that is that accountants should observe a standard of ethical or social responsibility. One set of difficulties concerns ethics education's ability to instill the chosen values and to make them stick after the educational process is completed. Instruction in accounting ethics is directed at people whose character-or lack there-of-has largely been formed by the time the instruction occurs. Although such instruction should increase the moral awareness of those who are already predisposed to listen, its effect on the basically self-interested, indifferent, or unethical is questionable. Even those who are positively influenced by ethics instruction, moreover, may still behave irresponsibly if their careers or their livelihoods require them to act in their client's financial interest. Recent pressure to include more ethics instruction in the accounting classroom has placed an emphasis on individuals who have a sense of moral responsibility. An emphasis on codes of conduct may result in students' failure to â€Å"develop discretion and judgment . . . which are more than simply a matter of what acts are forbidden, which are required, and which are permissible† (Whitbeck, 1992, 128). Emphasis on rules may quickly become training in how to get around the rules while remaining technically legal. While students must be acquainted with professional codes of conduct as part of their preparation for a career, most researchers on ethics do not consider such material to be sufficient grounding in ethical training (Fulmer and Cargile 1993:Adams et al. 1995). A few years ago the American Institute of Certified Public Accounts (AICPA), the largest CPA membership organization in the world, decided that starting in the year 2000, new members would have to have 150 semester hour of college credits (5 Years) instead of the present four years to become a member (McGee). On the surface that does not appear to any big deal. No one has to become an AICPA member to practice public accounting or to be a CPA. But, there are several problems with this. The most obvious is that the major group harmed is the students (or parents), who must cough up another $10,000 or $20,000 for a fifth year of education. Then there is the added cost of not having a job for the extra year it will take to complete the fifth year, so there is another $25,000 – $30,000. But that is not all. The segment to the student population most harmed by this insane policy is the segment least likely to be able to pay for a fifth year – blacks, Hispanics, low-income students of whatever persuasion. Poor people and minorities, along with rest of us, will have to face an even higher barrier to entry into the accounting profession. (Metzger 1061) As mentioned earlier is additional education only going to make accountants more proficient at learning techniques to get around laws, perhaps using unethical behaviors? And at the same time force extra barriers on many disadvantaged people hoping to make an honest living? This may be only speculation of the could and could nots of what may happen, but serious food for thought. What are the consequences of these unethical behaviors? Accountants can be held liable for damages to clients and to third parties, he may also be found criminally liable for violation of securities, tax, and other laws. For criminal violations, he may be fined and imprisoned. Wrongful conduct may also result in the issuance of an injunction, which bars him from doing the same acts in the future. In addition, his wrongful conduct may be the subject of administrative proceedings by the Securities and Exchange commission and state licensing boards. An administrative proceeding may result in the revocation of an accountant's license to practice or the suspension from practice. Finally disciplinary proceedings may be brought against an accountant by professional societies such as the AICPA. Most states have statues imposing criminal penalties on accountants who willfully falsify financial statements or other reports in fillings under the state securities laws and who willfully violate the state securities laws or aid and abet criminal violations of these laws by others. Accountants have great responsibilities to their clients and to society. As an accounting major, doing research for this paper has helped to open my eyes to the many aspects of my intended profession. I have realized that it is a very trustworthy profession, held in the highest esteem by the public at large. I know that I must take my job and the trust instilled in me very seriously. I hope that this paper has enlightened you to the pitfalls many certified public accountants face today, both with ethical standards and with impending educational requirements.

How to Get Rid of Fleas in Your Home

If you’re an experienced pet owner, you know that where theres one flea, there are undoubtedly more. Effective flea control requires treatment of both the pet and the home, including the use of products that address the entire flea life cycle. That will require treating your pet and cleaning your home thoroughly, perhaps more than once.   The Life of a Flea There are many flea species, but the most common one in the United States is  Ctenocephalides felix, commonly known as the cat flea. These parasites thrive off the blood of mammals like cats, dogs, even humans. They love warm, moist places, and they breed like crazy, which is what can make infestations so serious.   Fleas go through four stages in their life cycle: egg, larva, pupa, and adult. Eggs hatch within 12 days of being laid. The larval stage lasts from four to 18 days. During this time, they feed on things like dead skin cells and dander, but they dont bite like adults do. Flea larvae next enter a pupal stage and lie dormant for anywhere from three to five day. Its the adult fleas that are the true pests. Theyre hungry and bite their hosts in order to feed off the blood they draw. Theyre also mobile, capable of leaping from host to host. And theyre prolific. An adult female can begin laying eggs within 48 hours of her first meal, on average 50 eggs a day. And fleas can live for two or three months, breeding until the end. Treating Pets To stop fleas, you need to break their life cycle, which means eliminating the eggs, the larvae, and the adults. Since your pet is the most likely host, start there. Begin by consulting your veterinarian, who can recommend a course of treatment based on your pets health and living situation. Many vets suggest topical products, often called spot-on treatments, or oral treatments. Popular treatments include Frontline Plus, Advantage, Program, and Capstar. These products are usually applied or administered monthly or every few months, and most require a prescription. Its worth pointing out that a small number of pets have an allergic reaction to these treatments, which can be fatal if not treated immediately. The Humane Society of the United States offers safety tips for using flea treatments on its website. Your vet may also suggest bathing your pet with an anti-flea shampoo to kill fleas living on your pets body, followed by a thorough combing with a flea comb to catch any remaining pests. But fleas can be persistent. If your pet goes outdoors, it can pick up new fleas. Likewise, your pet will become reinfested if you dont also treat your home. Cleaning Your Home Remember, the flea eggs drop off your pet. Flea larvae dont feed on blood; they can find everything they need to live in your carpet. After you treat your pet with an approved flea-control product, you need to get rid of the fleas in your carpet and on your furniture. Otherwise, the flea eggs will keep hatching, and you will be fighting a perpetual infestation of hungry fleas. If you act as soon as you notice Fido scratching, you may only need a vacuum and a washing machine for this step. Mild flea infestations can often be managed with some persistent housework. Concentrate your efforts on the areas of your home where your pet spends the most time.   Wash pet bedding, toys, blankets, linens, and throw rugs in hot water. Anything your pet has been on or near that can fit in the washing machine should be laundered. Use the hottest water possible.Vacuum carpets thoroughly. If possible, use a vacuum with a beater bar, as these do a better job of moving the carpet pile and getting to the flea eggs and larvae deep within the rug. Make sure you pick up any clutter; dont just vacuum it. Also, move the furniture and vacuum underneath. Some people recommend putting a flea collar inside the vacuum bag to kill the fleas once youve collected them.Vacuum upholstered furniture. Even if you dont think your pets climb on your furniture, they are. There are probably flea eggs hidden in your couch cushions. Vacuum all the cushions, cracks, crevices, and seams carefully. Remove the cushions and vacuum underneath them, too.Throw away the vacuum bag when done. If you dont, the fleas can escape. If you have a bagless vacuum, be sure to empty it immedia tely after sweeping and get the trash out of your house to prevent reinfestation. For bad infestations, you may also need to do a little more cleaning and use an environmental flea treatment: Vacuum baseboards, trim and other places where fleas may still be hiding. If you didnt catch the flea infestation early enough, or in a year when flea populations are higher than usual, you may need to be more thorough with your housekeeping chores. In addition to vacuuming carpets and upholstered furniture, use a crevice tool to remove fleas from under baseboard molding and kitchen cabinets. Look at the places where your pets eat, sleep, and play, and try to find the places where fleas may still be hiding.Apply a pesticide labeled for flea control to infested carpets and furniture. The key is to use the right product, one that contains an insect growth regulator. For flea control, look for spray products that contain methoprene or pyriproxyfen. These products disrupt the flea life cycle, ending the fleas ability to reproduce in your home. Flea Control Options Both chemical and natural products are available. Raid, Vibrac, and Frontline are three popular brands of chemical flea treatments for the home. Foggers can sometimes be effective, but they require very careful handling and use. Youll need to vacate your home for two or three hours while the fogger is on, plus youll need to clean all cooking and food-prep surfaces and utensils afterward. The Environmental Protection Agency has more tips for safe use of foggers on its website. If you want to avoid using harsh chemicals, there are some natural flea-control solutions as well, but they are often less effective. Vets Best and Nature Plus are two natural brands that earn good consumer reviews. You can also try adding a drop or two of essential oil (such as eucalyptus or lavender) to a spray bottle filled with water, then spraying the mixture on pet bedding, furniture, and rugs. Some experts also recommend spreading  diatomaceous earth on rugs, bedding, and furniture, but it can be difficult to vacuum up. Regardless of the product you choose, follow all directions on the label. Do not apply these products to your pet or your skin. Keep pets and children off of treated carpets and furniture for three days, which will allow the treatment time to work, then thoroughly vacuum. Treat Again as Needed If you still find fleas after following the steps above, you may need to do another round of cleaning and vacuuming 14 to 28 days later. If you live in a warm climate where fleas can thrive outdoors year-round, you may also need to have your yard treated. Dont forget to reapply monthly topical flea treatments to your pets and check regularly for fleas. Use a flea comb on your pets. You can purchase a fine-toothed flea comb at your local pet supply store or at your veterinarians office. Comb your cat or dog regularly, and examine the comb for fleas, flea eggs, or flea dirt which may be a sign of flea bites.Use a lint roller on your clothing. After your cat or dog has been on your lap, do a quick check of your clothing with a lint roller. Use the kind that comes with sticky tape, and roll it over your pants and shirt. Check the sticky tape for evidence of fleas. For all but the most severe flea infestations, these steps should get fleas under control. In some cases, such as when a multi-unit apartment building becomes heavily infested with fleas, the services of a professional pest control specialist may be required to eliminate the pests. Sources Crosby, Janet Tobiassen. The Life Cycle of the Flea. TheSpruce.com. 4 April 2017.  Flowers, Amy. Get Rid of Fleas in Your Home, Step by Step. WebMD.com. 18 February 2018.Humane Society of the United States staff. Flea and Tick Product Ingredients. Humanesociety.org.