Wednesday, January 6, 2021

Environmentally Responsible Electric Lighting Design

A systems approach to electric lighting is needed to achieve maximum energy - effective and energy - efficient design. This is the energized system that includes luminaires and controls. Luminaire is the technical names for the complete lighting unit that consists of the housing, lamps, ballasts, and transformers as well as light - controlling elements such as reflectors, shielding devices, and diffusing media.

In making any lighting decision, illumination needs must be established and trade - offs between electric lighting options need to be assessed. The cost - value benefit analysis for each option includes energy cost, lighting - system costs, operating costs, and lighting - quality issues. Lighting - quality issues cover a range, including employee productivity and absenteeism, security and safety, business image and environmental “mood,” and accommodation of spatial changes.


Efficiency of the electric lighting system is dependent on characteristics of each individual component as well as how the components work together to produce electric illumination. There are different measures of efficiency related to different components of the system.

  • Lamp efficacy is the technical term to describe how efficient a lamp converts electricity of visible light. This is stated as lumens per watt (LPW).
  • Luminaire efficiency is the ratio between the light output from the fi xture and the light output generated by the lamps it houses. This is stated as a percentage.
  • Coefficient of utilization (CU) is concerned with the amount of light that reaches the work surface relative to the amount of light produced by the lamp. This measure of efficiency is affected not only by the characteristics of the luminaire but also by the size and shape of the room, as well as the reflectance of the ceiling, walls, and fl oor. Standardized procedures are used by the manufacturer to establish a CU table of values for each luminaire.
  • Visual comfort probability (VCP) is a value that indicates how much glare a luminaire is likely to produce. The room dimensions infl uence this rating. A VCP of 80 or higher is considered necessary for highly computerized offices. This number means that 80 percent of the users located in the least desirable spot in the space would not be bothered by direct glare from an even pattern of luminaires mounted on or in the ceiling.
  • Ballast factor (BF) is the relative light output produced by a lamp and ballast system relative to the manufacturer ’s rated light output of the lamp itself. A high ballast factor means fewer lamps and ballasts are needed to achieve a specific level of illumination. A low BF ballast would permit lowering the light level in an overilluminated space without replacing or rearranging existing luminaires.


Effective lighting is dependent on perception of the appearance of the light as well as the general appearance of the space, especially related to color. Two additional ratings are used to identify the color appearance of the light source and its effect on surfaces in a space:
  • Color temperature (CT) or correlated color temperature (CCT): CT is used for lamps with fi laments, including standard incandescent and halogen sources. CCT is used for nonfi lament light sources, including fl uorescent and metal - halide lamps. This measure, stated in degrees Kelvin (K), is based on the color change of a test wire as it is heated. The color of the wire goes from yellow to orange/red to white to blue as it increases in temperature. Sunny daylight at noon is about 5,500K, an overcast sky is about 7,000K, a 100 - watt incandescent lamp is about 2,800K.
  • Color rendering index (CRI) provides an estimate of how “ natural ” or expected a standard set of colors appear when seen under a specifi c lamp relative to their color appearance under the standard test source with the same CCT. This latter appearance is rated as 100 CRI. Current energy codes defi ne a rating of 70 CRI as the minimum value for lamps used in most interior environments.
These two color ratings are linked to energy effi ciency in recent research findings. As CCT increases, the blue content of the light increases. A 5,000K light source has been found to provide more contrast and better resolution of details. With this bluer light, it is possible to design with lower foot - candle levels to achieve a perception of the same brightness in a space.

Light sources with a higher CRI have been linked to energy efficiency. The IESNA Lighting Handbook reports that “ lamps with color rendering indexes of 70, 85, and 100 require about 10%, 25%, and 40% lower illuminance levels than lamps with a CRI of 60, respectively, to achieve impressions of equivalent brightness ” (Rea 2000). Thus, the higher the CRI number of the light source, the brighter a space should appear with the same energy use.

Sunday, September 27, 2020

Environmentally Responsible Daylighting Design

 Daylight, part of the nonenergized system, is an important component of environmentally responsible lighting design. Architectural daylighting design decisions can help or hinder the potential for effective use of daylight and achieving visual comfort inside buildings. While a detailed development of daylighting design is beyond the scope of a discussion of environmentally responsible interior design (ERID), the integration of daylighting with electric lighting is important. “ Daylighting, ” a section from the Whole Building Design Guide , provides a substantial discussion of all aspects of daylighting (Daylighting n.d.). An understanding of the issues, benefits, and guidelines related to daylighting is important to developing ERID.

Windows provide a psychologically important connection to the outdoors. Access to a view and interaction with daylight provide valuable environmental information: a dynamic measure of time passage, information about immediate weather conditions, and a sense of place. Having a view to the outside reduces eye strain, allowing the muscles contracted from extended near - focus to relax. Research evidence from education, corporate, retail, and health-care settings is confi rming the positive health and performance impacts of daylighting.

A major benefit of daylighting is the reduction in both fossil fuel and electric energy use. Fossil fuel is used for heating and cooling, while electric energy is used for lighting. Daylighting can provide savings of 35 to 65 percent in electric use for lighting and 20 to 60 percent overall energy savings. Coupled with energy - efficient and effective electric lighting, the savings will be even greater. Energy budgets can be substantially reduced to well below American Society of Heating, Refrigerating and Air - Conditioning Engineers, Inc. (ASHRAE) Standard 90.1 requirements.

Daylighting does have limitation and liabilities that must be addressed for its successful use in interior environments. Using daylight requires recognition of the variability of this light source due to geographic location, time of day, time of year, and weather conditions that affect the sky; this affects the color of the light as well as the brightness and distribution.

The problem is not so much daylight but, rather, sunlight. A direct beam of sunlight is an extremely high source of light as well as heat. Thus, direct sunlight as a light source needs to be minimized, while maximizing the use of diffused daylight. Excessive heat gain and ultraviolet damage to materials can be two negative results of daylighting that need to be balanced with the advantages gained from daylighting in a particular building. Glazing material can be selected to reduce both of these problems. Tinted glass though can block biologically important wave lengths and/or distort the color spectrum of daylight. Glazing should have high visible - light transmission (VLT) qualities and a low solar - heat gain coefficient (SHGC) for maximum daylighting benefits.

Glare is the biggest daylighting problem; it reduces the ability to see details. A school study of daylighting effects reported that glare from windows reduced test scores 15 to 25 percent. High contrast is created along with glare, either directly between the glazed surface and adjacent interior surface or indirectly where light falls on a surface. Daylight needs to be balance with light - colored interior surfaces to reduce the potential for these strong contrasts. Guidelines note that the window should not be more than 100 to 300 times as bright as the objects in the room. Furthermore, direct sunlight on task areas or reflected glare on television and computer screens can be avoided through orientation and shading. “ Daylight factor ” is a calculation used to compute the amount of daylight outside compared to a point inside.

One daylighting strategy involves “ harvesting ” light. The idea is to minimize direct sunlight penetration while maximizing daylight use. Integrating high ceilings and bringing in daylight from two directions help to increase daylight utilization. Sidelighting uses vertical glazing. For daylighting use, the glazing is located high on the wall or overhead, while vision or view glazing is positioned within a seven - foot distance from the floor.

Light shelves are a frequent addition to high lights or clerestories to increase the penetration of daylight further into the interior space. Continuous horizontal windows are better than individual windows or vertical ones. A light shelf facilitates deeper daylight penetration into a space, but it contributes even more to a uniform distribution of the daylight. A light shelf can also be effective in blocking direct sun at certain times of the year and day.

Light shelves

Toplighting is any daylighting delivered from the ceiling plane. This location for daylighting provides the potential for even distribution of daylight throughout a larger space and integrates well with electric lighting. Wall washing is possible with toplighting. Care in the design and placement of skylights is needed to avoid the problems of glare, excessive heat gain, and harsh contrast from direct sunlight. If toplighting is designed using deep wells and/or diffuse materials, these problems will be reduced. Sawtooth ceilings, light monitors, and north - facing clerestory windows, which were all popular in industrial settings a century ago, are effective ways to harvest daylight.

The following are Strategies and principles for effective daylight in interior spaces:
  • Collaborate early with design team members to maximize building features that support daylighting.
  • Provide soft, uniform light throughout the space.
  • Provide thermal barriers for the windows to reduce heat gain or loss during unoccupied times.
  • Use HVAC (heating, ventilating, and air - conditioning) to compensate for the additional radiation during daylighting hours.
  • Provide glare - control and heat - gain shading systems.
  • Orient a worker ’ s sight line away from windows, preferably with daylight coming from the side of a person. Rear lighting may produce shadows on the work material.
  • Integrate automatic controls with a manual override for the shading system.
  • Provide control mehanisms that adjust electric illumination when adequate daylighting is available. These include: on/off system, continuous dimming, and step switching or step dimming for individual ballasts and lamps .
  • Use a closed - loop photosensor that reads electric light and daylight in preference to an open - loop sensor that reads only the daylight.
  • Use an advanced lighting system with electronic ballasts to supplement daylight to maximize energy savings.
In developing an integrated daylight and electric light strategy, light levels from daylight need to be higher in a space than comparable light levels from electric light. The footcandle perception of the two is not equal. The IESNA suggests a rule of thumb: add 1 lumen of electric lighting for the loss of 2 – 3 lumens of daylight. While maximizing daylight use is an environmentally responsible strategy, electric lighting is a necessary supplement. Understanding and integrating daylight with electric light is important for achieving energy - effective and efficient electric lighting.

Monday, December 2, 2019


There are mainly two types of R.C.C. footings:

1. One way reinforced footings.
2. Two way reinforced footings.

1. One Way Reinforced Footing: These footings are for the walls. In these footings main reinforcements are in the transverse direction of wall. In longitudinal directions there will be only nominal reinforcement.

2. Two Way Reinforced Footings: For columns two way reinforced footings are provided.
The following types of the footings are common:

(i) Isolated Column Footings: If separate footings are provided for each column, it is called isolated column footing. Figure 1 shows a typical isolated column footing. The size of footing is based on the area required to distribute the load of the columns safely over the soil . These footings are provided over a 100 to 150 mm bed concrete. Required reinforcements and thickness of footing are found by the design engineers. Thickness may be uniform or varying.

(ii) Combined Footings: Common footings may be provided for two columns. This type of footing is necessary when a column is very close to the boundary of the property and hence there is no scope to project footing much beyond the column face. Figure 2 shows a typical combined footing. The footing is to be designed for transferring loads from both columns safely to the soil. The two columns may or may not be connected by a strap beam.

(iii) Continuous Footings: If a footing is common to more than two columns in a row, it is called continuous footing. This type of footing is necessary, if the columns in a row are closer or if SBC of soil is low. Figure 3 shows this type of footing.

(iv) Mat Footing/Raft Footing: If the load on the column is quite high (Multistorey columns) or when the SBC of soil is low, the sizes of isolated columns may work out to be to such an extent that they overlap each other. In such situation a common footing may be provided to several columns as shown in Fig. 4 Such footings are known as raft footings. If the beams are provided in both directions over the footing slab for connecting columns, the raft foundations may be called as grid foundation also. The added advantage of such footing is, settlement is uniform and hence unnecessary stresses are not produced.

Wednesday, November 27, 2019


This type of foundations are commonly used for walls and masonry columns. These foundations are built after opening the trenches to required depth. Such footings are economical up to a maximum depth of 3 m. As these foundations are suitable depth, they are grouped under shallow foundations.

Figure 1 shows a conventional spread footing for a wall and Fig. 2 shows it for a masonry column.


Before building these footing trenches are opened to required depth and the soil is rammed well. Then a plain concrete of mix 1 : 4 : 8 is provided. Its thickness varies from 150 to 200 mm. Over this bed, stone masonry footing is built. It is built in courses each course projecting 50 to 75 mm from the top course and height of each course being 150 to 200 mm. In case of wall footing the projections are only one direction while in case of columns, they are in both directions. The projection of bed concrete from the lowest course of foundation masonry is usually 150 mm.

Friday, September 6, 2019

Dimensions of Foundation

Guidelines for minimum dimensions are given below:

(a) Depth of Foundation: For all types of foundations minimum depth required is calculated
using Rankine’s Formula:

However in any case it is not less than 0.9 m. Finding safe bearing of the soil is an expert’s job,
and it is found after conducting tests in field or in Laboratories. However general values for common
soils are listed in Table 1.

(b) Width of Foundation: Width of wall foundations or size of column footing is determined by
first calculating the expected load and then dividing that with SBC. Thus,

Friday, February 9, 2018

Plank floor

Plank floor

An alternative to the inverted T-beam is the pre-cast plank floor. These are reinforced lightweight concrete planks which sit side by side, supported as before by the internal leaf of blockwork. The planks are built into the blockwork at the sides as well as the ends and therefore restraint straps are not necessary in this instance.

Plank floor

Monday, September 25, 2017

Trust Me, I'm Engineer

Monday, September 11, 2017

Combined Rectangular Footing.

Fig. 3.14 shows a combined rectangular footing for two columns A and B carrying loads


W1 and W2, and spaced l centre to centre. If W' is the weight of the footing and qs is the safe bearing capacity, the footing area is given by

Suitable values of length L and breadth B of the footing are chosen, so that B x L = A. The longitudinal projections a1 and a2 should be so chosen that the C.G. of footing coincides with the C.G. of the two loads.

From the above, the projection a1 and a2 can be determined.

The net upward pressure p0 is given by

This net pressure intensity is used for structural analysis and design combined footing. A combined foundation may be either of reinforced cement concrete (R.C.C.)  or of steel grillage type.

(i) Combined rectangular footing of R.C.C. A rectangular footing of R.C.C consists of a reinforced concrete slab which is designed for both longitudinal  bending as well as transverse bending. If the distance between the columns. Typical details of a R.C. footing, without longitudinal beam, are shown in Fig. 3.15 Fig. 3.16 Shows typical details of rectangular footing, having longitudinal beam. The longitudinal beam may be provided either below the footing slab, or it may project above the slab.

(ii) Combined steel grillage rectangular footing. Such a footing is provided to support two steel stanchions.

The upper tier of steel joists receives the loads from the two columns and transfers the load to the lower tier. Fig. 3.17 shows typical details.

Monday, April 11, 2016

Structures: Folded Plate

The effect of folding on folded plates can be visualized with a sheet of paper. A flat paper deforms even under its own weight. Folding the paper adds strength and stiffness; yet under heavy load the folds may buckle. To secure the folds at both ends increases stability against buckling.

1. Flat paper deforms under its own weight
2. Folding paper increases strength and stiffness
3. Paper buckling under heavy load
4. Secured ends help resist buckling
Structures: Folded Plate

Friday, December 11, 2015

Vierendeels Configurations

Vierendeels may have various configurations, including one-way and two-way spans. One-way girders may be simply supported or continuous over more than two supports. They may be planar or prismatic with triangular or square profile for improved lateral load resistance.  Some highway pedestrian bridges are of the latter type.  A triangular cross-section has added stability, inherent in triangular geometry.  It could be integrated with bands of skylights on top of girders.

When supports are provided on all sides, Vierendeel frames of two-way or three-way spans are possible options.  They require less depth, can carry more load, have less deflection, and resist lateral load as well as gravity load.  The two-way option is well suited for orthogonal plans; the three-way option adapts better to plans based on triangles, hexagons, or free-form variations thereof.

Moment resistant space frames for multi-story or high-rise buildings may be considered a special case of the Vierendeel concept.

1  One-way planar Vierendeel girder
2  One-way prismatic Vierendeel girder of triangular cross-section
3  One-way prismatic Vierendeel girder of square cross-section
4  Two-way Vierendeel space frame
5  Three-way Vierendeel space frame
6  Multi-story Vierendeel space frame

Vierendeels Configurations

Monday, November 30, 2015

Joist, Beam, Girder

Joists, beams, and girders can be arranged in  three different configurations: joists supported by columns or walls1; joists supported by beams that are supported by columns2; and joists supported by beams, that  are supported by girders, that are supported by columns3.  The relationship between joist, beam, and girder can be either flush or layered framing.  Flush framing, with top of joists, beams, and girders flush with each other, requires less structural depth but may require additional depth for mechanical systems.  Layered framing allows the integration of mechanical systems. With main ducts running between beams and secondary ducts between joists.  Further, flush framing for steel requires more complex joining, with joists welded or bolted into the side of beams to support gravity load. Layered framing with joists on top of beams with simple connection to prevent displacement only

2  Single layer framing: joists supported directly by walls
3  Double layer framing: joists supported by beams and beams by columns
4  Triple layer framing: joists supported by beams, beams by girders, and girders by columns
5  Flush framing: top of joists and beams line up May require additional depth for mechanical ducts
6  Layered framing: joists rest on top of beams Simpler and less costly framing May have main ducts between beams, secondary ducts between joists

A Joists
B Beam
C Girders
D Wall
E Column
F Pilaster
G Concrete slab on corrugated steel deck

Joist, Beam, Girder

Thursday, October 15, 2015

Gerber Beam

The Gerber beam is named after its inventor, Gerber, a German engineering professor at Munich. The Gerber beam has hinges at inflection points to reduce bending moments, takes advantage of continuity, and allows settlements without secondary stresses.  The Gerber beam was developed in response to failures, caused by unequal foundation settlements in 19th century railroad bridges.

1.  Simple beams over three spans
2.  Reduced bending moment in continuous beam
3.  Failure of continuous beam due to unequal foundation settlement, causing the span to double and the moment to increase four times
4.  Gerber beam with hinges at inflection points minimizes bending moments and avoids failure due to unequal settlement
Gerber Beam

Monday, September 7, 2015


Optimizing long-span girders can save scares resources.  The following are a few conceptual options to optimize girders.  Optimization for a real project requires careful evaluation of alternate options, considering  interdisciplinary aspects along with purely structural ones.

1  Moment diagram, stepped to reflect required resistance along girder
2  Steel girder with plates welded on top of flanges for increased resistance
3  Steel girder with plates welded below flanges for increased resistance
4  Reinforced concrete girder with reinforcing bars staggered as required
5  Girder of parabolic shape, following the bending moment distribution
1  Girder of tapered shape, approximating bending moment distribution


Tuesday, June 16, 2015

Structures: Bending, Effect of Overhang

Bending moments can be greatly reduced, using the effect of overhangs.  This can be describe on the example of a beam but applies also to other bending members of horizontal, span subject to gravity load as well.  For a beam subject to uniform load with two overhangs, a ratio of overhangs to mid-span of 1:2.8 (or about 1/3) is optimal, with equal positive and negative bending moments.  This implies an efficient use of material because if the beam has a constant size – which is most common – the beam is used to full capacity on both, overhang and span.  Compared to the same beam with supports at both ends, the bending moment in a beam with two overhangs is about one sixth !  To a lesser degree, a single overhang has a similar effect. Thus, taking advantage of overhangs in a design may result in great savings and economy of resources.

1. Simple beam with end supports and uniform load
2. Cantilevers of about 1/3 the span equalize positive and negative bending moments and reduces them to about one sixth, compared to a beam of equal length and load with but with simple end support.

Structures: Bending, Effect of Overhang

Thursday, April 23, 2015

Portal Method For Rough Moment Frame Design

The Portal Method for rough moment frame design is based on these assumptions:

•  Lateral forces resisted by frame action
•  Inflection points at mid-height of columns
•  Inflection points at mid-span of beams
•  Column shear is based on tributary area
•  Overturn is resisted by exterior columns only

1.    Single moment frame (portal)
2.    Multistory moment frame
3.  Column shear is total shear V distributed proportional to tributary area:
4.   Column moment = column shear x height to inflection point
5.  Exterior columns resist most overturn, the portal method assumes they resist all
6.  Overturn moments per level are the sum of forces above the level times lever arm of each force to the column inflection point at the respective level:
7.  Beam shear = column axial force below beam minus column axial force above beam Level 1 beam shear:
Portal Method For Rough Moment Frame Design

Monday, March 16, 2015


Global moments help to analyze not only a beam but also truss, cable or arch. They all resist global moments by a couple F times lever arm d:
The force F is expressed as T (tension) and C (compression) for beam or truss, and H (horizontal reaction) for suspension cable or arch, forces are always defined by the global moment and lever arm of resisting couple.  For uniform load and simple support, the maximum moment M and maximum shear V are computed as:
For other load or support conditions use appropriate formulas


Beams resist the global moment by a force couple, with lever arm of 2/3 the beam depth d; resisted by top compression C and bottom tension T.


Trusses resist the global moment by a force couple and truss depth d as lever arm; with compression C in top chord and tension T in bottom chord.  Global shear is resisted by vertical and / or diagonal web bars. Maximum moment at mid-span causes maximum chord forces.  Maximum support shear causes maximum web bar forces.


Suspension cables resist the global moment by horizontal reaction with sag f as lever arm.  The horizontal reaction H, vertical reaction R, and maximum cable tension T form an equilibrium vector triangle; hence the maximum cable tension is:


Arches resist the global moment like a cable, but in compression instead of tension:
However, unlike cables, arches don’t adjust  their form for changing loads; hence, they assume bending under non-uniform load as product of funicular force and lever arm between funicular line and arch form (bending stress is substituted by conservative axial stress for approximate schematic design).

Monday, March 2, 2015

Seismic Design, Eccentricity

Offset between center of mass and center of resistance causes eccentricity which causes torsion under seismic load.  The plans at left identify concentric and eccentric conditions:

1  X-direction concentric
    Y-direction eccentric

2  X-direction eccentric
    Y-direction eccentric

3  X-direction concentric
    Y-direction concentric

4  X-direction concentric
    Y-direction concentric

5  X-direction concentric
    Y-direction concentric

X-direction concentric
    Y-direction concentric

Note: Plan 5 provides greater resistance against torsion than plan 6 due to wider wall spacing Plan 6 provides greater bending resistance because walls act together as core and thus provide a greater moment of inertia.

Seismic Design, Eccentricity

Thursday, February 12, 2015

Structures - Horizontal Floor and Roof Diaphragms

Horizontal floor and roof diaphragms transfer lateral load to walls and other supporting elements.  The amount each wall assumes depends if diaphragms are flexible or rigid.

1.  Flexible diaphragm

Floors and roofs with plywood sheathing are usually flexible; they transfer load, similar to simple beams, in proportion to the tributary area of each wall. Wall reactions R are computed based on tributary area of each wall. Required shear flow q (wall capacity)

2.  Rigid diaphragm

Concrete slabs and some steel decks are rigid; they transfer load in proportion to the relative stiffness of each wall.  Since rigid diaphragms experience only minor deflections under load they impose equal drift on walls of equal length and stiffness. For unequal walls reactions are proportional to a resistance factor r.
Structures - Horizontal Floor and Roof Diaphragms

Wednesday, January 28, 2015

Structures - Design Response Spectrum

The IBC Design Response Spectrum correlate time period T and Spectral Acceleration, defining three zones.  Two critical zones are:  

T < TS          governs low-rise structures of short periods
T > TS          governs tall structures of long periods


T = time period of structure (T ~ 0.1 sec. per story - or per ASCE 7 table 1615.1.1)
TS = SDS/SD1  (See the following graphs for SDS and SD1)

Wednesday, January 7, 2015

Seismic Design

Earthquakes are caused primarily by release of shear stress in seismic faults, such as the San Andreas fault, that separates the Pacific plate from the North American plate, two of the plates that make up the earth’s crust according to the plate tectonics theory.  Plates move with respect to each other at rates of about 2-5 cm per year, building up stress in the process.  When stress exceeds the soil’s shear capacity, the plates slip and cause earthquakes.  The point of slippage is called the hypocenter or focus, the point on the surface above is called the epicenter.  Ground waves propagate in radial pattern from the focus.  The radial waves cause shaking somewhat more vertical above the focus and more horizontal far away; yet irregular rock formations may deflect the ground waves in random patterns.  The Northridge earthquake of January 17, 1994 caused unusually strong vertical acceleration because it occurred under the city.

Occasionally earthquakes may occur within plates rather than at the edges.  This was the case with a series of strong earthquakes in New Madrid, along the Mississippi River in Missouri in 1811-1812.  Earthquakes are also caused by volcanic eruptions, underground explosions, or similar man-made events.

Buildings are shaken by ground waves, but their inertia tends to resists the movement which causes lateral forces.  The building mass (dead weight) and acceleration effects these forces.  In response, structure height and stiffness, as well as soil type effect the response of buildings to the acceleration.  For example, seismic forces for concrete shear walls (which are very stiff) are considered twice that of more flexible moment frames.  As an analogy, the resilience of grass blades  will prevent them from breaking in an earthquake; but when frozen in winter they would break because of increased stiffness.

The cyclical nature of earthquakes causes dynamic forces that are best determined by dynamic analysis.  However, given the complexity of dynamic analysis, many buildings of regular shape and height limits, as defined by codes, may be analyzed by a static force method, adapted from Newton’s law F= ma (Force = mass x acceleration).

1  Seismic wave propagation and fault rupture
2  Lateral slip fault
3 Thrust fault
4 Building overturn
5 Building shear
6  Bending of building (first mode)
7  Bending of building (higher mode)
E Epicenter
H Hypocenter